Horticultural Therapy

By Laurie Daniels, CSU Extension – Denver Master Gardener since 2014

As gardeners, we all know the calming effect of preparing the soil for planting, the satisfaction of methodically placing and covering a row of tiny seeds, the patience of watering and weeding the garden bed and the joy of seeing the first green shoots emerge. We may not think of it as therapy, but throughout history, the therapeutic benefits of garden environments have been widely recognized.

DCH Harvest. Photo by Laurie Daniels

According to the American Horticultural Therapy Association’s (AHTA) website, Dr. Benjamin Rush, known as the “Father of American Psychiatry,” was one of the first to document the positive impact that working in a garden had on people with mental illness. After the World Wars, using gardens in the rehabilitation of hospitalized veterans gained credibility and expanded the use of gardening into occupational/physical therapy and beyond.

Today, AHTA has a defined program for certification of horticultural therapists that includes coursework in plant science, human science and horticultural therapy and a significant internship requirement. The Association has defined a therapy garden as, “A therapeutic garden is a plant-dominated environment purposefully designed to facilitate interaction with the healing elements of nature.”

The Denver Botanic Gardens has a Manager of Therapeutic Horticulture, Angie Andrade, and a beautiful Sensory Garden that uses “specialized gardening techniques and structures to minimize barriers and maximize people’s abilities” to enjoy and interact with plants. Among other horticultural therapy programs offered by the Gardens is one at Chatfield Farms to support the therapeutic needs of post-9/11 military veterans.

In a meeting with Denver Master Gardeners who work at the Denver Children’s Home (more on that below), Angie Andrade helped us understand how horticultural therapy works. As she related, a garden always needs care so there is always something you can find to do. The repetitive nature of garden tasks like weeding, raking and planting seeds brings calm and helps rewire the brain. Being outside in the garden helps people learn to nurture plants and, by extension, learn empathy and responsibility. The garden is a structured, safe space where we are connected to other living things, so it opens us up to the natural world but in a supportive environment.

Horticultural Therapy in Action

As mentioned above, the Denver Master Gardeners have a volunteer program based in horticultural therapy with the Denver Children’s Home (DCH). DCH is the oldest non-profit organization in Colorado, originally started as an orphanage in 1876. It was renamed the Denver Children’s Home in 1962 and now operates programs including residential, day treatment, in-home therapy and Discovery home, a group home. DCH focuses on treating children and families who have suffered severe trauma, abuse, or neglect, with serious mental health issues.

In 2013, a former parking lot on the grounds of DCH was converted to an 870 square foot raised bed vegetable garden and a perennial healing garden under the leadership of Rebecca Hea (DCH Executive Director) and Carol Earle (Denver Master Gardener). With this addition, horticultural therapy joined art and music therapy, physical exercise and other therapeutic activities that help to build a lifetime of coping skills for the children.

From April through September, small groups of children spend one hour a week in the gardens, working with Denver Master Gardener volunteers. In 2021, with direction from the volunteers, the kids planted donated seeds and plants, weeded and watered, mulched, thinned rows of carrots and beets, and enjoyed harvesting over 300 pounds of produce that could be eaten as snacks or cooked in DCH kitchens.

The children grew a wide variety of plants, from beans and cauliflower to tomatoes and watermelon. The garden also boasts strawberries (a popular spring treat), raspberry and blackberry bushes and many beautiful perennial and annual flowers. In fact, making small bouquets for their rooms was one of the favorite activities of the teen-age boys who worked in the garden with me.

3 Sisters garden. Photo by Kathy Roth

A centerpiece of the DCH vegetable garden is a large circular bed that hosts a “Three Sisters” garden based on a companion planting technique developed by Indigenous farmers in North America. The legend speaks of three sisters who are different yet love and thrive when they are together. In a garden, it refers to a mixed cropping technique that has corn, beans and squash planted together to support each other’s growth. The corn provides a “pole” for the beans to climb, the beans are a nitrogen-fixing plant that supports the corn’s growth and the squash creeps along the ground, shaded by the corn and beans and keeping weeds from affecting the other plants. The garden produced a bounty of produce for the children while helping them learn about the power of companion planting in the garden.

During my volunteer season in the garden, I saw horticultural therapy in action with the boys eagerly monitoring the growth of fruits and vegetables each week, taking responsibility for watering beds, learning how to tell if different vegetables were ready to harvest, carefully staking overgrown tomatoes, pruning late growth and helping put the garden to bed.

Child’s Bouquet by Laurie Daniels

Over the summer, they shared excited sightings of giant worms while weeding and happily made “beetlejuice” by handpicking Japanese Beetles off grapevine and into cups of soapy water. Their joy at being in the garden was evident and the children seemed to grow throughout the season along with their plants.

The Denver Children’s Home garden is an outstanding example of horticultural therapy at work and a rewarding experience for Denver Master Gardener volunteers.

Winter Watering

By Uli Klein, CSU Extension – Denver Master Gardener since 2019                                                

After the fall clean-up is complete and our sprinkler systems are winterized, it’s easy to think the gardening season is over and it’s time to bask in the late autumn sunshine. Because the visible parts of plants go dormant in late fall, it is very easy to overlook the importance of off-season moisture. But to ensure the health and longevity of the landscape, it’s wise to keep an eye on the amount of moisture received during the next several months. In Denver, relying solely on fall and winter precipitation alone can be insufficient for trees, shrubs, turf, and perennials.

According to the graph above, the average amount of annual precipitation in Denver is ~14 inches and varies significantly from year to year. For example, we received 26 inches of precipitation in 2015, but only 9.5 inches in 2020. November through February are often the driest.

How does lack of moisture affect trees and plants?

Under continued dry conditions, the delicate hairs on feeder roots can eventually be permanently damaged and unable to absorb water or transport nutrients. Most root hairs are in the top 12 – 15 inches of the soil and often extend beyond the dripline. These roots provide moisture to the upper parts of the tree. If these structures cannot supply enough water, leaves will wilt at first; and if drought conditions continue or worsen, twigs or entire branches may die. This loss of branches is a tree’s attempt to resize the canopy in relationship to how much water the roots provide and is called dieback. I’ve often spotted dieback on trees in Denver parks. This University of Kentucky article further explains how dry seasons affect woody plants.

In the spring of 2020 many Denver trees, especially pines and arborvitae, died from a combination of pronounced temperature swings, unseasonably cold temperatures, and a mid-winter drought. Signs of stress are not typically visible until spring, when evergreen needles yellow or drop, or in severe cases, plants are lost.

Newly planted trees and shrubs are particularly vulnerable to extreme conditions and need extra TLC during the cold seasons. To fully establish, trees generally need one growing season for each inch of trunk caliper. During that time, they are particularly sensitive to lack of moisture, temperature swings, and strong, drying winds.

Herbaceous perennials can also suffer from lack of moisture, although the damage is less eye-catching than that exhibited by shrubs and trees. While it is easier and less costly to replace a perennial than a large tree or conifer, replacement plants will likely be smaller, take time to establish, and are unnecessary expenses.

Our lawns will also benefit from watering during prolonged dry periods of 4–6-weeks. Find tips for winter care at Lawn Care – 7.202 – Extension (colostate.edu).

When deciding how much to water, take local factors into account: A good layer of mulch reduces evaporation and helps plants to retain more moisture, while those in more wind-prone sites and/or facing south-west require extra moisture. BTW: 10” of average snow, 4 to 5” of wet snow, or 15” of powdery snow are equivalent to 1” of rain.

Let’s recap the facts

  • In Colorado, the winter months (November through March) are often the driest.
  • Precipitation varies from year to year – monitor local weather conditions.
  • Make newly planted trees, shrubs, and perennials a priority since they need more moisture than established ones.
  • Don’t forget that your lawn needs extra water.
  • Healthy trees and plants are an asset that are under-appreciated until they need to be replaced.

Tips for winter watering

  • Water only when it’s above 40°F, ideally around midday so the water is absorbed before nightly temperatures dip.
  • Apply a gentle stream of water, either from a watering can or a hose with a watering wand, so the water soaks in and doesn’t pool.
  • In dry conditions, all plants (trees, shrubs, perennials, turf) benefit from extra water from October through March. Pay particular attention to recently planted specimens or those in windy locations or south-west exposures.
  • A good layer of mulch reduces watering needs.

How much water is needed?

  • Approximately 10 gallons of water per each diameter of the tree trunk per month (i.e., a 2” tree needs ~20 gallons/month) distributed at several locations within its dripline.
  • Newly planted:  approximately 5 gallons every 2 weeks.
  • Established <3ft: approximately 5 gallons per month.
  • Established >6ft: approximately 18 gallons per month.

Final thoughts

Preparing this blog has really motivated me to do the right thing for my plants this winter season. I hope that it will convince you, the reader, that winter watering is worth the effort and preserves precious plants. Therefore, fellow gardeners, keep your watering can at the ready!

Additional references




Holiday Gifts from Your Garden Bounty

By Lois Margolin, CSU Extension – Denver Master Gardener since 2011

The garden is put to bed, autumn is in full swing, and the holiday season is near. Luckily this summer and fall I planned ahead for holiday gifts by drying herbs, freezing grated zucchini, making tomato sauce and salsa, pickling cucumbers, and green beans, preserving fruit into jams and jellies, and more. If you’re also interested in making homemade gifts from the garden, consider some of my favorites below.

Salsa: Too many tomatoes and enough spaghetti sauce? Switch to making salsa.  Freezing the salsa in small batches is much quicker than canning. 

Herbs d’ Provence: Friends return the decorative jars and containers I use for this herb blend in hopes that I’ll refill and return them as “bread and butter” gifts during the holidays.

Zucchini bread: I bake loaves in large tin cans (about 30oz.). Remove the paper labels and clean the cans thoroughly. Grease the inside well and pour in the batter until a little more than half full. Remove the breads as soon as they are cool enough to handle. The loaves cut beautifully into round serving pieces. Wrap loaves in colorful cellophane available in craft stores and tie with a pretty bow.  To make the gift more special, include a topping. Soften a package of cream cheese. Add orange or lemon rind and a small amount of sugar. Mix well. Package the cream cheese mixture in small disposable containers. The spread tastes great on zucchini bread.

Canned food in jars: Assorted garden goodies such as my homemade dill pickles, dilled green beans, pickled green cherry tomatoes, peaches, apple sauce and jams are a welcomed gift. Dress up the jars with fabric lids by cutting square or round eight-inch pieces of cotton fabric with pinking shears. Remove the ring that holds the lid in place. Put the piece of fabric over the lid and reattach the ring. Purchase rectangle, oval or round labels at an office supply store. Design your label on the computer or attach a nice holiday card to the jars.

Pies, crisps, crumbles and cobblers: I froze a lot of apple slices this fall after harvesting a bumper crop. Thaw apples and drain off some of the liquid. Use your favorite recipe and disposable pie tins for delicious gifts. I also froze sliced rhubarb and strawberries. This combination makes for a great pie. If you grew pumpkins, now is the time to cook them for Thanksgiving pies. I’m convinced fresh pumpkin makes the best pie! Dress up the gift by baking it in a pretty, reusable pie plate or 9 x 9 baking pan.

Teas: I love to create my own herbal teas. I find cute containers at craft stores, make labels and give these as gifts. My favorite blend is lemon balm and lavender used either as an herbal tea or combined with black tea for a stronger flavor. All varieties of mint are good, and rosemary also makes a nice winter drink when steeped in boiling water.

Dried flower arrangements: Homegrown gourds, cattails, pussy willows, lavender blossoms, long stems of herbs, hydrangeas and dried grasses make pretty fall arrangements. Mason jars, baskets, carved out pumpkins and old teapots make nice, inexpensive containers.

If you want to use your homemade goodies but make the gift more expensive, get creative. Create a gift basket or double spaghetti pot (bottom pot for water, insert strainer on top) around a theme such as an Italian dinner. Place your homemade spaghetti sauce up front. Add several packages of spaghetti, spaghetti serving spoon, garlic bread spread, and a loaf of Italian bread. Wrap it all in cellophane and tie with a huge bow. 

A breakfast bread tray for two can hold homemade jam, scones, a cute spreader, mint and black tea with a brewing strainer, and two large mugs.

For detailed directions on making some of the above-mentioned edible gifts, please refer to my Aug. 8, 2021, blog post: “The Fun Begins: Harvesting and Preserving Garden Fresh Vegetables.”

Horsing Around In the Garden & Kitchen

By Lori Williams, CSU Extension – Denver Master Gardener since 2016

I adore horseradish. I love the beauty and structure of the plant. It’s gorgeous with its wide, proud leaves standing up in the spring through summer and into fall. Horseradish leaves offer a unique texture and shape in the garden, and I want that drama in my landscape. When cut, the leaves look amazing in a vase mixed in with any flowers imaginable.

I also adore the horseradish root – a bold flavinator that is simple to harvest for culinary enjoyment. It’s easily transformed into a creamy condiment after a quick dig and cleaning, some grating and the addition of salt and vinegar. This “pickled” horseradish sauce is delish with grilled meats and a spoonful mixes wonderfully into marinades, soups, mashed potatoes and more. Mix 50/50 with your favorite ketchup and you have hearty cocktail sauce.

Though a delicious recipe enhancer, don’t underestimate the aromatic intensity unleashed as the root is cut and grated. Horseradish has a pungent compound called “allyl isothiocyanate” that is released when it makes contact with oxygen. This compound’s chemical reaction with air creates the “hot” smell and taste of horseradish.

 My best advice: Do not lean in and breathe deep while processing horseradish. The Horseradish Information Council’s #1 suggestion while harvesting? A room with good ventilation. The concentrated aromatics released can affect eyes, skin, nasal passages and possibly balance as it can knock you back a few steps!

Next let’s talk about harvesting this tasty root. As mentioned, the steps are simple and the processing into preserved or pickled horseradish doesn’t take much time. The most common harvesting advice is to wait until after its foliage has died back, after a few frosts.

Is this because a few freezes cause some savory chemical reaction affecting the root, or some other science-y explanation? Probably! However, my research shows this advice around harvest timing is more about convenience. After a frost or two, most gardens and garden chores are wrapped up, and horseradish is something that can survive through colder temperatures.

A few tips for harvesting horseradish:

  1. Select and cut around roots with a long-bladed shovel aiming down versus “in” as the roots are long. Gently loosen soil around root and remove from the ground. You want as much of the long root as possible and to avoid breaking them in the ground (which promotes spreading).
  2. Rinse root in water, scrub enthusiastically. Cut into safely manageable pieces, remove rough skin with a vegetable peeler. Note: Isothiocyanate begins to release with abandon at this point, so proceed with caution.
  3. Rinse bright white root flesh a final time, chop into small pieces your food processor or blender is able to grate. This is a very dense, fibrous root and can challenge blades of processors and blenders so be kind to your appliance, and to yourself, when lifting the lid to check grating progress. Don’t lean in close or breathe deep!
  4. Add a bit of salt to help the root breakdown and sweat. Water or ice cubes add moisture without significantly changing the taste and help “cream” the root. Process to desired consistency.
  5. Timing is important when adding vinegar since vinegar stops the enzymatic process and takes the root taste from mild to hot. Add immediately and the “temperature” of your sauce will be less than if you wait longer for a bigger bite in flavor.
  6. After processing scoop the pickled horseradish into a sterilized jar and refrigerate, freeze in ice cube trays, or go through the canning process and stash in your pantry.

I know many of you might be thinking, “Not in my yard. Horseradish spreads!” It does spread, but it can also be curtailed with routine diligence that doesn’t take much effort. I have 14- and 10-year-old plants, each about 3 feet in circumference. Maintaining this size has been very manageable and we enjoy and harvest horseradish all year long!

To keep your horseradish in check:

  • plant in a shady spot for slower growth, away from your favorite perennials
  • consider planting near compost piles; horseradish loves the ‘back 40’
  • slice out and compost unwanted starts/roots
  • plant in a very deep, two- to three-foot container
  • option for non-fans of the horsey hotness: plant and never harvest to contain growth

Handling roots carefully with intent when harvesting helps deter over-growth. Planted with purpose, horseradish can also eat up some space as a lush looking hedge along a border or on a berm. Maybe a splash of bold on a hell strip? Horseradish can thrive in almost any condition. It loves and is especially successful in full sun. It’s a strong plant in both stature and flavor, versatile in the kitchen, and a true beauty in the garden.

Bon appetite!

Additional reading:   https://pss.uvm.edu/ppp/articles/horserad.html  

Pollinator-Friendly Fall Garden Cleanup

By Jessica Harvey, CSU Extension – Denver Master Gardener since 2020

As we wrap up the season and put our gardens to bed, there are a number of ways we can help provide habitat for our pollinators in the process. Many pollinators will nest in the hollow of stems or wood. Others will use things like leaves, mud, plant hairs, and resin to build their nests for the winter. Rather than chopping everything down and clearing out the remaining debris, let’s consider whether any of it may be used by a pollinator this winter, or even next spring.

For those pollinators that like to nest within hollow stems, consider deadheading rather than chopping those stems down to their base. Stems can range 8 to 24 inches long, from both flowers and grasses alike, to be of use for cavity nesters. A nest within a hollow stem will typically house eggs, a food source and a natural plug of some kind that can be specific to the type of pollinator that are nesting within. A couple of great examples are leaf cutter bees (Megachile) and Mason bees (Osmia and/or Hoplitis). 

Remember to allow those same stems to decay and fall on their own in the spring as you don’t want to remove them until after the young have emerged for the season. If you grow raspberries doing so is easy, since you may need those prime canes for next year’s production.

Check out this great handout with diagrams highlighting some of the different cavity nesters from University of Minnesota Extension and their Bee Lab. 

Not to be forgotten, consider pollinators that are ground nesters as well. It’s important to leave some bare earth for these guys to burrow into for their nests. If you have pets or children, you may consider a place out of the way within your garden.

Another excellent resource is CSU Fact Sheet No 5.615 Attracting Native Bees to your Landscape which provides more information on different nesting materials and ways you can provide additional habitat specifically for native bees. 

Just like any other living thing, the main concerns for pollinators are food, water, and shelter. As we clean up and leave some debris intact for them as shelter, it’s also important to try to provide some clean water. It may be hard to do this during the winter but consider adding a tray with pebbles near your hollow stems or bare ground, and keep it topped off during the fall and spring. No need to buy anything specifically marketed as such, it can be as simple as the drip tray from a container you aren’t using.

As we wrap up for the season and begin planning for the next, also consider whether you have a year-round source of both pollen and/or nectar within your garden to encourage a strong pollinator population. Ground covers, winter blooming crocus and early blooming grape hyacinths (Muscari) will help to bridge some of the gaps.

CSU Factsheet 5.616 Creating Pollinator Habitat gives a glimpse of all the things to consider as you plan your garden as a pollinator habitat, including some plants to consider for all season provisions.

It’s important to remember our pollinators not just during the peak of the season when we need them for our flower, fruit, or vegetable production. They provide so much for us and we need to try and return the favor wherever we can. 

Denver Master Gardeners Look Back at the Growing Season – Part 2

Compiled by Linda McDonnell, Denver Master Gardener since 2013

Welcome back to part two of our garden season recaps. We hope you enjoy this look at the wins, challenges, and surprises from Denver Master Gardeners. If you missed part one, you’ll find it here.

HUMMINGBIRD BANQUET  Barb Pitner, Denver Master Gardener since 2012

This season’s goal was to create a garden to attract and feed hummingbirds. I started by removing a twelve-foot-wide circle of lawn with a two-foot-wide circle or “bullseye” in the center. The soil of this center area was prepped with compost into which four scarlet sage vines (Salvia coccinea) were planted around a four-foot-high decorative tower.

The remainder of the full-sun, brightly colored pollinator garden was filled with containers, which encircled the scarlet sage and descended in height from the center.

The tall scarlet sage vines were surrounded by containers of vibrantly colored ‘Giant’ zinnias alternating with containers of crocosmia varieties including ‘George Davidson’ (yellow), ‘Lucifer’ (deep red-orange), ‘Emily McKenzie’ (red-orange-maroon with a yellow eye). Cypress vines (Ipomoea quamoclit) were added to the crocosmia displays.

The outer ring of the garden was made up of smaller containers, brimming with lower growing annuals such as marigolds, blue Victoria salvia, red calibrachia, and red-yellow lantana.

Daily watering, regular feeding, and deadheading insured constant blooms from July to September. In addition to hummingbirds, the garden was regularly visited by native, honey, and bumble bees. All have been kept in good supply of nectar and pollen.  

WINTER-SOWN BAPTISIA  Susan Tamulonis, Denver Master Gardener since 2018

Last December I was given thirty-eight Baptisia seeds (Baptisia spp; variety unknown, aka wild or false indigo) from a neighbor. This gift launched a multi-season challenge to nurture, document, and transform the seeds into healthy plants. Baptisia is in the Fabaceae (bean) family and requires cold temperatures to germinate – perfect timing for this project.

The dense, hard-coated seeds were treated to two boiling water baths and then soaked for two more days. The seeds were then planted in “mini-greenhouses,” constructed from milk jugs (one 1-gallon and two ½-gallons). The uncapped containers were cut in half horizontally and drainage holes were poked in the bottom. Seeds were sown in the base of the containers, lightly covered with soil, and watered. The top portion of the containers were replaced, creating dome-like planters. The containers were placed in a shady outdoor spot immediately after planting and were regularly checked for moisture and good drainage.

In April, to allow for more light, the top half of the containers were removed; germination began in May. By mid-June, seedlings were four to five inches tall with three sets of leaves. It was now time to plant them in full sun. In August, the seeds yielded seventeen healthy plants for a 58% germination rate.

And here’s where the story takes a turn…I returned from a fall vacation to find the young plants were mowed down by a hungry visitor, likely a rabbit. So while the winter-sowing process was successful, the plants didn’t survive!

A FUN & BENEFICIAL SURPRISE  Jodi Torpey, Denver Master Gardener since 2005

My biggest gardening success this season gave new meaning to the old saying about keeping one’s ear close to the ground. That’s because I grew an ear in a container of radishes.

Although I didn’t set out to grow a body part in my garden, I was delighted to see this flesh-colored, earlike growth pop up among the radishes during this year’s cool, wet spring. My “ear” was most likely a type of cup fungus belonging to the genus Peziza. These fungi are real bodies – the fruiting bodies – of cup fungi that usually live underground but can grow above ground in mulch or compost when conditions are right.

While they don’t all look like ears, they’re all good for gardens because they break down organic matter to make nutrients available to plants. An ear growing in that container turned out to be a real fun guy.

A TREE WORTH WAITING FOR!  Lori Williams, Denver Master Gardener since 2016

After a four-year delay in planting any tree, finally this summer a long-awaited, lovely peach tree found a home in our yard. It came with baby peaches all over, but we popped most off so the energy would go to the roots. The only decent gladiolus I planted this year were around the new peach tree – and we enjoyed nine very tasty peaches in mid-August. Highlight of our summer!

NATIVE POLLINATOR GARDEN: YEAR TWO  Ann Winslow, Denver Master Gardener since 2019

Last year, I shared my adventure creating a pollinator garden using native plants on this blog. You’ll find the posts here and here. This year, I’ve watched and recorded what has flourished and what has struggled – maybe because of weather, where the plant was sited, and in some cases, for reasons I can’t tell.

One big success was chocolate flower (Berlandiera lyrata). At one end of the garden, three plants became massive, merging into one enormous display, which will be divided in the Spring. They have been abuzz with native pollinators since June. Just what I hoped for!

In contrast, wine cups (Callirhoe involucrata) has struggled. It’s possible that the heavy spring rains caused it to grow leggy, splay out on the ground, and have few blooms. I’m cutting back the long, dead stems now as I see it’s getting new growth in the center.

Always something to learn. Every year is a new adventure in gardening.

Many thanks to the Denver Master Gardeners who allowed us to peak into their gardens, learn from their experiences, and be inspired by their results.

Denver Master Gardeners Look Back at the Growing Season – Part 1

Compiled by Linda McDonnell, Denver Master Gardener since 2013

It’s time to take stock of the gardening year – the ups, downs, and lessons learned. In this two-part series, eleven Denver Master Gardeners share the highs, hiccups, and take-aways from the season. Let’s see what they’ve been up to!

A NEW ROCK GARDEN Steve Aegerter, Denver Master Gardener since 1999

If you attended the Rocky Mountain Chapter of the American Rock Garden Society’s 2021 Spring tour, you had the opportunity to visit Steve’s new rock garden, which was planted only a month before the June event. Steve explained that “Plants were either grown from seed or obtained through Denver Botanic Gardens, Colorado Native Plant Society, or the local American Rock Garden Society.”

The garden contains fourteen low-water plants including  ‘Butterfly Yellow’ mullein (Verbascum roripifolia), Freemont’s evening primrose (Oenothera macrocarpa freemontii), and a unique pale yellow upright bellflower, Campanula thyrsoides.

Steve is pleased with the garden’s progress and looks forward to it thriving on little to no supplemental water soon.

PILL BUG INVASION Felicia Brower, Denver Master Gardener since 2020

Heartbreak is waking up early to check on your plants, only to find them withered and discover that their stems have been destroyed. The majority of my cucumbers, squash, and beans were decimated no matter how many times I tried to replant them. I had three varieties of cucumbers, six varieties of squash, and five varieties of beans. All but two varieties of beans were killed. Out of the two beans that survived, half of the black-eyed peas were eaten but my Zuni Gold beans, a regional bean cultivated in the Southwest over many generations, were left untouched.

Moisture and too much organic matter in my raised beds lead to this explosive pill bug population. I’m working on amending that now, and next year I’ll take pest control seriously early on.

PICTURE PERFECT ‘RED ACRE’ CABBAGE Latasha Dunston, Denver Master Gardener since 2020

Seed grown ‘Red Acre’ cabbage (Brassica oleracea) was a highlight of Latasha’s West Washington Park community garden. An earlier attempt to grow this plant didn’t work, but this year, the results were stellar. “I kept the base leaves and root in place when I harvested, and the plant produced four new heads!” She’s hoping for more in a fall harvest, too.

ADD THIS ONION TO YOUR “MUST GROW” LIST Jill Fielder, Denver Master Gardener since 2013

This season, Jill’s best new find was bunching onions also known as spring or Welch onions (Allium fistulosum).

Jill reports that these flavorful gems can be planted when the weather is still chilly and harvested at any point during the growing season. Early on, use like tender scallions. Later, use the greens for stir fries and the bulbs as you would any small onion. Seed in a full row so you have plenty to harvest as the season progresses. Eat the entire tasty plant. There’s even a French Purple variety that offers rich beautiful color for snipping into salads or sprinkling over bubbly enchiladas. Didn’t plant enough the first part of the season, so planted more mid-summer. All were delish!

DAHLIA ADVENTURE & DREADED TWO-SPOTTED SPIDER MITES Cindy Hanna, Denver Master Gardener since 2010

Last fall I was given a treasure trove of dahlia bulbs that had been dug out of a bed in Park Hill. I was told to, ‘clean them off, split as needed leaving a bud on each piece, make sure they are dry, and store in a bin of perlite in a dark room until Spring. In Spring when they begin to sprout, plant according to varied directions online.’ High maintenance. They were slow to sprout and bloom but, wow, worth the work and wait!

When it comes to pests, I’m a bit of a live-and-let-live gardener. So, when my Master Gardener friend who is an avid plant and bug expert visited, I feared the worst. She identified two-spotted spider mites in my vegetable beds. If there had only been two, I could have ignored them. But there were thousands living on the underside of the yellowed foliage, sapping the energy and beauty from my cucumbers and beans.

RAVE REVIEWS FOR “GARDEN IN A BOX” Lynn Ireland, Denver Master Gardener since 2020

Rather than starting from scratch, Lynn decided to add pollinator-friendly plants to her established gardens. A highlight of her project was “Garden in a Box”, a collection of low-water plants, purchased through Resource Central in Boulder, which also comes with planting directions and design tips.

Several water districts offer “Garden in a Box” programs, some with rebate offers. Lynn suggests “It’s the perfect way for a novice gardener to begin or add to their gardens.”

Stand-out plants in the garden expansion included Agastache, Aster, Sea Kale, Mexican Sunflower, and Pitcher Salvia. “According to the hummingbirds, native bees, and Japanese Beetles, these two gardens have been bountiful all summer. I’m already excited for next season!”

Watch for more garden recaps next week

What Should I Do With All These Leaves?

By Gail Leidigh, CSU Extension – 2021 Denver Master Gardener Apprentice

After moving to Denver and having a yard to take care of for the first time, I had no idea what to do with the volume of leaves each fall from several large older trees. Do I rake them? Use a leaf blower? Do I hand clear them out of the plant beds? And, how on earth do I dispose of them?

Our small urban lot easily generated 30-40 full leaf bags annually and it seemed overwhelming. Denver natives may laugh at my initial confusion but having grown up in a region of the pacific northwest, where the vast majority of trees are evergreen, I simply had not dealt with this before. I have learned quite a bit about how to deal with leaves in the last few years and thankfully this has saved me time and unnecessary work.

The first couple of years I would remove leaves from plant beds either by blower or by hand, as I assumed this was the correct thing to do, but I later learned this is unnecessary. While leaves should always be cleared from hard surfaces such as sidewalks, stairs, and patios for safety reasons, it really is fine to leave them in plant beds over winter. I now know that this gives perennials and shrubs protection and nutrients for several months until springtime. It may not be the tidiest look, but there are many benefits, including giving insects a great place to live.

Leaves can be left on lawn areas as well but should be shredded to provide organic material that can break down easily. Realizing these two things have saved me a tremendous amount of effort. 

And then, what to do with the leaves you need to dispose of? While you can bag and dispose of them in the trash or sweep them in the street for the street sweepers, but please avoid these practices. Both of those options create lots of unnecessary waste.

With a little more effort, you can put your leaves to good use. The Denver area has three great options.

  • Denver Recycles offers a seasonal program called LeafDrop, where you can bag up your leaves and drop them off at various locations around the city. The leaves are then turned into compost, available to Denver residents at a discounted price later in the year. Follow the link for dates, times, and drop off locations. Note that paper leaf bags (available from many hardware stores) are strongly preferred as they can be composted as well. 
  • Denver Composts is a convenient composting bin pickup program, where you can place food scraps, non-recyclable paper (paper towels, pizza boxes, etc.), and yard waste. And an added bonus – this includes weeds!

There is a quarterly fee of $29.25 (discounted if you pay annually), and this comes with the green compost bin (slightly smaller than a recycle bin) that is picked up weekly, and a small countertop kitchen pail.

As I don’t have the space or resources to compost myself, I have found this to be a wonderful way to reduce trash and get rid of yard waste, while contributing to the composting program for our city. 

Lastly, check out this PlantTalk article about Why Leaves Change Color in the Fall and enjoy the cooler seasons coming!

Turf Grass Management for Autumn

By: Steve Aegerter, CSU Denver Extension-Colorado Master Gardener since 1999

Why is there such a mystery about maintaining a healthy Kentucky Bluegrass lawn? Depending on who you talk to and what you read in books and on the internet, you can get lots of conflicting advice. No wonder homeowners sometimes get confused and downright addled!

Proper turf management is actually easier to achieve than one might think. If a picture-perfect lawn is your goal next season, you can definitely achieve it by following these few simple research-based recommendations this fall.

Fertilization. Fall is the absolute best time to fertilize with nitrogen fertilizer. This is simply called a winterization process and should be performed in October-November. Benefits of this process are better fall and winter color, earlier spring green-up, increased shoot density, improved fall, winter and spring root growth, and enhanced storage of energy reserves. This also eliminates the need to fertilize in the spring.

Mowing. The proper mowing height is 2 to 3 inches. Ignore common advice to mow the grass shorter in the fall. Also leave the grass clippings on the lawn – they will not contribute to thatch accumulation. In fact, they are comprised primarily of nitrogen and as they break down, they add nitrogen to the soil.  So, in essence, you are fertilizing every time you mow.

Core Aeration. Core cultivation should be performed in the fall, and for that matter also in the spring. This assists in the management of thatch, reduces compaction, increases gas exchange, enhances water filtration, improves root growth, and provides an ideal environment for seed germination.

Overseeding. If the lawn is thin or has bare spots, overseed immediately after core aeration. Don’t skimp – purchase the best blend of sun/shade grass seed you can find. Taking the bargain route can lead to years of woe.

Power raking. This practice generally does more harm than good as it can damage roots or remove turf. Skip it, it is not necessary.

Watering. It is far better to water less often, but deeper. Grass benefits more from a weekly 45-minute soak than a daily 10-minute drink. Best of all, by watering correctly, you’ll likely use less water and save money. Winter watering is advisable during prolonged dry spells of 3-4 weeks. For more information on winter care, visit Fall and Winter Watering – 7.211 – Extension (colostate.edu).

Following these simple recommendations will provide a huge assist in obtaining a lush green lawn next summer. For more lawncare information, visit CSU’s Lawn Care Fact Sheet 7.202.

Outside to Inside – Hardening Off Houseplants

By Lori Williams, CSU Extension-Denver Master Gardener since 2016

Bringing houseplants in from gardens is all about timing. Reverse planning from outside to inside starts with your area’s average first frost date. Denver’s average FFD is roughly September 15th! Colorado summers can have a long wind down or be very abrupt, either way the goal is to avoid shocking houseplants or worse, letting them suffer damage or freeze due to temps they can’t withstand. It’s best if plants have time to “harden off”, meaning they adapt from warm days to the interior temp of your home, with less cold night exposure.

A wonderful friend and esteemed gardener I know diligently lines up houseplants for thorough garden hose spray downs for 2-3 weeks, horticultural oil applied the next week, all with time allowed for sitting and drying or airing out. Then and only then are plants welcomed back inside the house. 

I respect the time management, scheduling expertise, and TLC regimen and strive for such skills and discipline! However, down to my toes I know I am amazingly less organized and reactionary in my garden.  Last night’s a great example: windows wide open I woke to grab a quilt at 3am, the fresh air was so (deliciously) chilly! This morning my first thought: get the houseplants ready to come inside before it’s too cold at night. Waa laa – the planning committee just hit town!

I use the following steps, completed in a production line, that can usually be completed in a couple of hours. This year, with 17 houseplants outside, in a range of sizes, I got them processed in about 2 hours, including time when plants were soaking or draining. Big plants can need 2 people to move, but overall, it’s a manageable job solo.

Here’s how to get your plants looking sharp and bug-free:

  1. Watch weather forecasts for predicted temps and storms then pick a day when you have time and go for it.
  2. Group plants in shaded warm area, shooing away Daddy Longlegs as you go. Pick a spot where you can get them saturated and they can also drain.  If they haven’t seen direct sun all summer, now is not the time to let them boldly sit in it as leaves easily scorch. 
  1. Quick-clean plants of dried leaves and debris.  With a hose spray plants and pots from every angle to knock off dirt, dust, cobwebs, debris, buggy-spidey-like things that hang on foliage. Up-spray undersides of leaves.  Delicate plants? Adjust hose pressure or use a spray bottle.
  2. Run enough water in a kiddy pool, garbage can, or bathtub to submerge containers; a tarp, drop cloth and towels can also be useful.  Add a small amount of soap to water (detergents or degreasers can damage or kill sensitive plants), I like Dr Bronner’s castile soap.  You can use diluted insecticidal soap for this step, too.

5. Fully submerge each container (for tall pots set in water, splash water in pot until water sits on top of soil). Soak 10-15 minutes until no more bubbles come up from soil.  Now the soil’s completely hydrated and in turn should drown little buggy organisms (instant in-pot composting, right?). Gently wash all non-submerged leaves, stems and branches with soapy water while the pot soaks by splashing water over the plant. It’s also an easy time to wipe down container’s sides, rim and bottom so it’s house-clean.

6. After thoroughly soaked, remove container and let it drain. Gently spray plant & container with hose until soap-free.  Pleas no direct sun during this step, either, as water sitting on leaves magnifies the sun’s impact. While plants are still outside, rough up top 1-2” of soil and add fresh potting soil. My favorite tool for this is a cocktail fork.  It’s tiny enough to not damage roots, sturdy enough to get the job done. Plants that are root-bound can be up-potted at this time.

After completing the steps, protect your plants and effort. Mud rooms, covered porches, and garages are made for this. From there plants can be moved out during warm daytime temps and back in overnight for a couple days – truly ‘hardening’ them ‘off’.  

Additional resources:

Sunburned House Plants

Bringing House Plants Inside

Putting the Garden to Bed: End-of-Season Advice