Wild About Natives: Fun Uses For Native Plants

By Kathy Roth, CSU Extension – Denver Master Gardener since 2018

Late summer native gardens offer a variety of opportunities for educational, tasty, and hands-on experiences. From preparing healthy snacks and drinks to creating a throw-back-to-the-sixties tie-dyed t-shirt, here are some activities to try with your family and friends during the dog-days of summer. And while you are at it, spread the word about the importance of native plants!

Enjoy Your Bounty

  • Harvest sunflower seeds (Helianthus annuus) before the birds do!  Learn more about this popular garden plant here.
  • Eat woodland strawberries (Fragaria vesca) right off the vine or try your hand at making tasty preserves.
  • Make rose hip tea from the native woods’ rose (Rosa woodsii). Try this recipe from “Fruits of Your Labor”, a cookbook by the Colorado Forestry Service: Combine 3-4 cups of rose hips and 2-3 cups of water; boil for 20 minutes. Strain the liquid to remove pulp. Enjoy hot or cold.

Spice Up Your Meals

  • Native onions add flavor to many dishes. Examples are nodding onion (Allium cernuum), Geyer’s onion (Allium geyeri), and prairie onion (Allium textile).
  • The fruit, or berry-like cones of Rocky Mountain juniper, (Juniperus scopulorum) add a flavor twist in German potato salad or sauerkraut.
  • Yucca glauca flowers make a tasty addition to salads.

Get Crafty

  • Gather the red and green leaves of creeping barberry (Mahonia repens, recently renamed Berberis repens), to use as holiday decorations.
  • My granddaughters and I had fun using natural dyes to create tie-dyed t-shirts.
  • The stems, leaves, and petals of native yarrow (Achillea millefolium) and sunflowers (Helianthus annuus) produce natural dyes in shades of yellow, green, or gold. This USDA publication details several more native plants and their pigment colors.
  • Ready to create your own tie-dyed masterpiece?
    • Start with a clean natural fiber t-shirt.
    • Prepare the dye bath by combining chopped, fresh plant material and water in an enamel vessel or a pot you won’t need again. Simmer for roughly an hour, adding water as needed.
    • Allow the liquid to cool. Strain and discard plant material.
    • To create the design, use twine to tie tight knots in the wet t-shirt.
    • Add the shirt to the dye bath and simmer for two hours or longer to achieve desired color. Turn off heat and allow to cool.
    • Use rubber gloves to remove the shirt and the twine; rinse till the water runs clear, then air dry.
    • Tie-dyed items should always be washed separately as the color may bleed.

Take a Mini-Excursion

If you need a quick get-away, don’t have access to the plants for these activities, or want to take a deeper-dive into uses for natives, you may enjoy:

What ideas do you have for other simple family garden projects using native plants? Please add them in the comments section.

Check out our archives for more articles from this series.

How to Use and Preserve Fresh Herbs from Your Garden

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

My May blog post gave instructions for planting an herb garden in a strawberry pot. Now it’s time to begin harvesting and cooking with those garden-fresh, delicious herbs.

The middle of May had unusually hot weather and daily watering was a must for plant survival. I set my irrigation system to water every morning for 4 minutes. When I went out of town for two weeks, I thought the garden would be fine, but the weather turned cool and rainy.

The result was water-logged plants in the lower pockets of the strawberry pot. Plus our yard became home to a large number of baby rabbits. What the water didn’t kill, the rabbits ate!

I replaced the herbs that died and harvested the herbs that started flowering to keep them growing. After cutting off 1/3 of each herb plant, I labeled them because herbs can look similar after they’ve dried.

After washing the herbs and letting them air dry, I plucked the leaves off the stems and put them into pie tins to dry for two weeks until they were fully dried and brittle.

This is the lazy way to dry herbs. Other methods include using an electric dehydrator, leaving the herbs in the oven with the light on overnight, microwaving, and hanging the herbs to dry in the air.

The CSU Extension Fact Sheet on Preserving and Using Fresh Herbs is a comprehensive resource for making the most of your herbal harvest. The fact sheet gives ideas for drying, freezing and storing, plus lists for matching specific herbs to their best culinary uses.

For best flavor, package whole herb leaves and wait to crush them right before using. Dried leaves can be stored in plastic bags and airtight containers.

Be sure to label and date the bags, then place the packages in a dry, dark place like a cupboard or drawer. Use dried herbs within a year for maximum flavor.

Easy Herb Recipes from the Garden

Make Herbes de Provence

One of my favorite ways to use dried herbs is to make Herbes de Provence to use on steamed vegetables and stir fry dishes, in soups and on meats.

A typical Herbes de Provence recipe blends together a combination of dried herbs such as thyme, rosemary, savory, marjoram, oregano, parsley and lavender flowers.

When attractively packaged, this herb mix also makes great hostess and holiday gifts. I find small glass jars with airtight lids at hobby shops and make my own labels.

Use Oregano and Sage

I dry a lot of oregano and sage to use all winter. Place a small amount of dried oregano in the palm of one hand and rub hands together to crush it into a powder that’s perfect for seasoning lasagna, spaghetti sauce and other recipes. Use sage for seasoning roast beef, lamb, chicken and turkey.

Drink up Mint, Lavender and Rosemary

Mint, lavender and rosemary make great flavorings for tea. Use fresh leaves throughout the summer and dried in winter. I like strong black tea so I pour boiling water over the tea leaves and herbs letting them steep for 5 to 10 minutes.

For herbal tea omit the black tea leaves. Brew herbal teas in boiling water and then chill for iced tea. Rosemary also adds a nice flavor.

Don’t use herbs in sun tea because it’s the perfect medium for bacteria growth. “Sun tea gets warm enough to brew tea, but it does not get hot enough to kill a ropy bacteria called Alcaligenes viscolactis that may be present in the water or in the tea or herb leaves,” according to Iowa State University and Extension in “Celebrating Iced Tea Safely.”

To avoid problems with bacteria, steep fresh herbs in boiling water, cool and then add to sun tea made using black tea leaves. If you prefer 100 percent herbal tea, let the steeped herb liquid cool and add to hot or cold water for iced tea.

Enjoy Fresh Basil

A caprese salad is a delicious way to use garden-fresh tomatoes and basil. Simply slice a ripe tomato, top it with a slice of fresh mozzarella cheese, add chopped fresh basil and drizzle Balsamic vinegar over the top.

Another way to use fresh basil is by making basil sugar, a bright green treat. Combine l cup of sugar in a food processor with ½ cup of fresh basil leaves and ¼ tsp lemon zest. Pulse for 30 seconds or until the basil is fully ground. Use basil sugar to sweeten fruit, teas, lemonade, and to decorate cookies before baking.

The recipes using dried or fresh herbs are endless and too numerous to list here. Search online and browse through cookbooks for ideas to enjoy all the “fruits of your labor.”

Lesson learned: Herb gardens need constant attention for best performance. Monitor the weather, test the soil for moisture, harvest frequently and give your herbal strawberry pots love and attention. The rewards are worth the effort!

Grow & Give Colorado

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

Have you ever secretly left a pile of zucchini on your neighbor’s porch after dark? Does just the thought of canning one more jar of applesauce make you sweat?  Do you eat tomatoes at breakfast, lunch and dinner at a certain point in the summer?

If any of this sounds familiar, the CSU Grow & Give project is for you!

The Grow & Give project was created by Colorado State University Extension to make it easy for any gardener to get fresh produce, grown in their garden, distributed to people in need. By participating in Grow & Give, you will learn how to easily donate your extra produce to organizations that will welcome it.

What Produce Works Best?

Photo credit: Laurie Daniels

Let’s first talk about what is the best produce for donating. It’s best if the produce is easy to use by home cooks. It’s also important that your donation is easy to keep fresh and doesn’t need a lot of extra packaging to keep it safe during distribution. Some of the produce that Grow & Give recommends for donation include:

  • Melons
  • Tree fruit
  • Summer & Winter Squash (they’ll love that extra zucchini!)
  • Cucumbers
  • Roma or slicing tomatoes (no cherry or large heirloom tomatoes—too fragile)
  • Corn
  • Green beans
  • Carrots
  • Eggplant
  • Bulb onions
  • Peppers (sweet, mild, medium)

Your local organization may accept other items such as berries, kale, beets, etc. but check with them first.

How Do I Participate?

  1. The first step is registering your garden with the Grow & Give project. You can sign up by completing a short survey. Now, you are ready to garden!
  • Check out the many resources on the website including a free to download, 85-page full color Colorado Vegetable Guide (available in English and Spanish). The Guide covers topics including garden layout, soil preparation, watering, fertilizing, managing insects/pests in your garden and detailed descriptions for growing vegetables from asparagus to winter squash.
  • Next, find a nearby organization for your planned donation. You will find an interactive map on the website that lists organizations all over Colorado. When I registered, I was able to find three organizations near my home. It is important to find an organization early on, since many only accept donations on certain days/times of the week and ask that you contact them in advance of dropping off your produce. Be prepared!  NOTE: If you know a neighbor, perhaps a senior living on a fixed income, who would appreciate receiving some of your extra produce, Grow & Give also has an option for donating directly to a neighbor-in-need.
  • Now, enjoy working in your garden. If you find bindweed in your garden beds or discover aphids on your broccoli, go back to the Grow & Give website (https://growandgivecolorado.org) and look for the tab on “Insects, Diseases and Weeds” to find short videos and fact sheets about how to handle these issues and many others.
  • When you begin harvesting produce from your garden and find yourself with an  excess of zucchini or a bounty of beans, check back on the Grow & Give website for tips on safely handling your produce for donation. The tips cover everything from:
    • washing or not washing your produce (be sure to let the organization you donate to know if the produce has not yet been washed)
    • using clean containers (do not reuse grocery bags)
    • washing your hands thoroughly before you harvest
    • leaving your produce whole—do not chop or cut as it shortens its shelf life
    • time your harvest so your donation can be made immediately
Photo credit: Laurie Daniels
  • Just a few more steps will enhance your donation. You can find printable Grow & Give labels on the website to designate your donation as part of the project. And, weigh your donation so you (and the project) have a record of what you gave.  Grow & Give also has links to tasty recipes that can be made with the produce you donate—what a nice gift for the recipient of your fruit or vegetables!
  • Finally, head back to the website and tell Grow & Give about your donation—photographs and stories are welcome through social media as well—and enjoy the good feelings that flow from helping your neighbors.

“Grow Food, Share the Harvest” is the slogan of the Grow & Give project. I hope you will consider joining us in our efforts “to address food insecurity in our state, one garden at a time.”

Does Horticultural Vinegar Control Weeds?

By Linda McDonnell, CSU Extension-Denver Master Gardener since 2013

For some time, I’ve heard pros and cons about using horticultural vinegar to eliminate weeds. I’ll admit to being equal parts skeptical and curious about its effectiveness. If you’re also on the fence about this natural herbicide, you may find the answers to commonly asked questions helpful.

What is horticultural vinegar? 

Horticultural vinegar (also called herbicidal vinegar) is a 10% – 30% concentration of the active ingredient, acetic acid. By comparison, kitchen vinegar contains 5% acetic acid. To be clear, the vinegar on your salad won’t kill established weeds, and horticultural vinegar is definitely not food.

How should it be used?

While horticultural vinegar is a ‘natural’ herbicide, it is still toxic. Always wear protective clothing, gloves, and eyewear when handling it to avoid potentially serious vision, skin, or lung issues.

Garden centers sell horticultural vinegar in gallon containers. To use, carefully pour it into a spray dispenser. A small amount of surfactant, such as liquid soap, can be added to the vinegar to improve foliage coverage.

For best results, spray weeds on a warm, sunny day; complete foliage coverage is important.

Horticultural vinegar is a contact or burn-down herbicide; it will damage any foliage it touches within a few hours. Even slight overspray can damage the leaves of neighboring plants. 

If spraying around desirable plants, carefully isolate the target weed with a barrier such as heavy cardboard. Treatment is generally effective on annual weeds growing between cracks in patios and sidewalks.

How does it work? On which weeds?

Acetic acid destroys the cellular structure of foliage, causing the leaf to dry up and die. Vinegar does not move systemically through roots or stems, so many plants, especially perennial weeds, will grow back from the unaffected root system.

According to Colorado State University and the University of Maryland Extension, studies have shown vinegar works best at killing very young annual weeds with few leaves and weak root structures. “Very young” is defined as plants which have germinated within two weeks. More mature annual weeds will likely need additional applications and show varying degrees of results. Common annual weeds include purslane, knotweed, and prostrate spurge.

Not surprisingly, vinegar is least effective at permanently eliminating perennial weeds with extensive root systems or underground storage structures such as rhizomes, tubers, or bulbs.

Examples of perennial weeds include bindweed, dandelions, quackgrass, and thistle. If you’ve ever battled these weeds, you know they can be doggedly stubborn. Vinegar is not up for the challenge!

 Is horticultural vinegar worth using?

Many gardeners find it easier and more effective to pull weeds. Hand-weeding, combined with practices such as mulching and drip irrigation, is an excellent strategy for preventing weeds. For more information on preventive weed control see this CSU publication.

Vinegar proponents may find that treating weeds with a natural herbicide is preferable to applying chemicals such as glyphosate, the active ingredient found in Round Up™ and other herbicides. Control of annual weeds can be achieved and unsightly weed foliage may be eliminated quickly, although it can reappear. Finally, gardeners who suffer from back pain or creaky knees may find vinegar spray is a helpful alternative to physically pulling weeds.

Have you used vinegar to treat weeds? Would you try it? We’d love your comments.

Colorado Gardening Calendar for July

By Gail Leidigh
CSU Extension-Denver Master Gardener Apprentice since 2021

July is one of the best months for enjoying the beauty of your garden. Much of the preparing and planting work completed in prior months will have paid off at this point, and it’s wonderful to see, and taste, the results!

Because July is typically hot and dry, this is a good month to make sure your garden is getting the right amount of water and to remain observant for pest or disease problems.

A Gardener’s Yard and Garden Checklist for July

Mark your calendar to get these gardening to-do’s done in your yard and garden this month:

Vegetable Garden

  • Harvest your veggies, fruits, and herbs as they become ripe. Enjoy them now or find a way to preserve them for later.
  • Wondering what is going on with your tomatoes? July in Colorado can be a challenging month for them environmentally, with our wide temperature ranges and winds that prevent pollination. Some suggestions for protecting your tomatoes from these tough conditions are available in the Plant Talk article on Tomato Questions Abound in the Heat.
  • Late July and early August are the times to plant fall season vegetables such as peas, broccoli, and kale, so they’ll have time to mature before the first frost. The average first frost is mid-October for the Denver area, but can vary by several weeks from year to year. Advice on checking the germination times on the seed packet, and much more is found on this guide to planting these cool season crops.

Trees and Shrubs

  • Tree and shrubs need to receive adequate water to prevent leaf scorch, that occurs when dry winds remove moisture from plants faster than their roots can absorb.
  • Trim back perennial shrubs when they finish flowering to help them bloom next year on this season’s growth.
  • Avoid trimming trees when they are water stressed by hot and dry conditions – they need to conserve all the energy they can this time of year.

Lawn Care

  • While an established lawn should be watered deeply and as infrequently as possible, with high temperatures, a lawn may need as much as 2.5 inches of water or more per week. It’s also important to check your sprinklers for even coverage. The most common cause of brown and bare spots in the turf is water not reaching the area.
  • Are Japanese Beetles making an appearance in your neighborhood? Unfortunately, you’ll most likely notice when they do! The adults will start to appear around June, and are most active July through early August. During this time, the female adults lay their eggs in grassy areas, which then hatch and the grubs (larvae) start to feed on nearby roots. Make sure to mow your lawn high, which encourages strong root growth, and let the soil dry out a bit to help reduce the amount of turf damage from these insect pests. Japanese beetles can’t be eliminated entirely; however, there are a variety of ways to manage their presence.

Perennial Flower Beds

  • Dead-heading, which is removing spent and fading blooms, will help prevent spreading and re-seeding of perennials, if that’s not desired, and will encourage further blooming.
  • Keep pulling those weeds! Weeds that are not left to go to seed will help prevent more weeds later, saving you time and effort down the road.
  • Refresh mulch as needed, to a depth of about 4 inches, to help retain moisture in the soil and prevent weeds.
  • Plants that have grown tall and leggy may need to be supported, and cages or stakes are a good option.

Annual Flower Beds

  • Check the soil moisture in pots and hanging baskets frequently, as they will dry out quickly in the summer heat and wind.
  • Clear and thin out plants that are fading, and make room for planting fall annuals.
  • Dead-head to encourage growth of new blooms.

Other Projects

Take a look around your garden for empty spots and bare areas that could be filled in later. Also make note of any plants that are weak, dying, and will need to be replaced. This is a perfect time to make a plan ahead for a fall, a great season to divide, add, and replace perennials and shrubs before winter.

Need More Gardening Tips?

Please visit the CSU Extension Yard and Garden website for more seasonal gardening tips.

Wild About Natives: Native Vines

by Kathy Roth, CSU Extension-Denver Master Gardener since 2018

Vines are garden problem solvers – they can camouflage an unattractive view, provide shade, take advantage of vertical space, or enhance an existing structure, all while contributing visual interest and texture to the garden. Vining plants added to the landscape now will establish this season and can return for many years to come.

Wouldn’t the perfect vine be beautiful, easy to grow, and stop growing when it reached its desired size?  In reality, vines are vigorous growers and will likely need some training and pruning once established. Don’t let this deter you, as a beautiful, well-sited vine is worth the effort it takes to keep it in check.

Here are two native vines to consider adding to your landscape.

Native Clematis

Virgin’s Bower or Western White Clematis (Clematis ligusticifolia) grows to 20’ high and produces numerous small, white, star-like flowers in mid-late summer. Attractive, long-lasting seed heads cover the plant after it blooms.

Clematis vines prefer well-drained soil, a sunny location, and cool roots. A good tip is to mulch the base of the vine or plant low growing plants around the plant’s feet to shade the soil.

Visitors to the Denver Botanic Gardens can see Virgin’s Bower in the Gates Montane Garden and along the Cheesman Park gate.

Incidentally, clematis varieties are not always vining – Scott’s sugarbowls (Clematis scottii) is a native, 12” tall mounding plant with nodding blue bell-shaped flowers in late spring /early summer.  Learn more about this plant at PlantSelect.org.

Clematis ligusticifolia at Denver Botanic Gardens. Photo credit: Kathy Roth

Native Hops

Common Hops, Humulus lupulus, features large lobed leaves and papery pale green flowers. Visit our earlier post, Growing Hops in the Home Garden for growing and harvesting tips for beer brewing.

A word of caution: Some gardeners report developing a skin rash from the plant, so it is advisable to wear garden gloves when handling it.

If you’ve never seen the hops plant, you can find it vigorously growing on the north wall of the Denver Botanic Gardens parking structure.

Native vs. Non-Native Vines

As mentioned in this Wild About Natives post, there are numerous horticultural and environmental benefits to growing native plants of all kinds. While native plants are highly desirable, this CSU PlantTalk Colorado publication notes that many non-native vines have acclimated to Colorado conditions too.

The Colorado Weed Management Association cautions gardeners against growing the following vines:

  • Silver Lace Vine (Fallopia bald schuanica) – an aggressive, non-native, white flowering vine which drops massive amounts of seeds and chokes out surrounding plants.
  • Virginia Creeper (Parthenocissus quinquefolia) – a non-native which is a magnet for the dreaded Japanese Beetle, which will devour its foliage and move on to your other plants, too. To learn more about Japanese Beetles, visit this CSU Fact Sheet.
  • Native Grapes (Vitis riparia) – another extremely popular target for Japanese Beetles. Unless you dream of having a vineyard, you’ll want to avoid this plant.
  • Chinese Clematis (Clematis orientalis) – a yellow blooming vine which is on the Colorado Noxious Weed List.
Hops at Denver Botanic Gardens. Photo credit: Kathy Roth

Final Thoughts

As always, I encourage you to visit the Colorado Native Plant Society website to learn more about creating native landscapes. You will also find the “Guide to Non-Invasive Plants” from the Colorado Weed Management Association an excellent resource for selecting native alternatives to non-native plants.

See you in July for Wild About Natives: Not Just Pretty Plants But Useful Too!

How to Build a Three-Bin Composting System

By Rikki Hanson
CSU Extension-Denver Master Gardener since 2014 and a Denver Urban Gardens (DUG) Master Composter since 2013

Composting is an amazing process that produces one of the best soil amendments gardeners can use. One of my favorite composting systems uses three bins for creating brown gold in your own backyard. This composting system is efficient and gives the option of having two bins to work with at all times. It can also be built to fit any space, making it easy to maintain.

To Build a Three-bin Composting System, you’ll need:

  • Gloves
  • Untreated barriers for the three bins, such as bricks, cinder blocks, nontoxic landscape timber, chicken wire, 2×4 construction lumber, wooden pallets, etc.
  • Pitchfork or shovel
  • Tarp or plastic cover
  • Sifter

Step 1: Finding a Location for Compost Bins

In our semi-arid climate it’s important to locate the three-bin system on a level site, in a semi-shady location that’s protected from drying winds. With our hot summers and intense sunlight, compost in a south or southwest-facing location could potentially heat up too much, killing the living decomposers.

Step 2: Building the Bins

Set up the bins to fit your space, such as 3x3x3-feet or 5x5x5-feet using bricks, blocks, lumber or your choice of building material to create three separate bins.

CSU Extension explains the three-bin system in the Fact Sheet on Composting Yard Waste as an efficient wood structure that allows plant material to be aerated by turning it from one bin to the next as it decomposes.

Once the three-bin structure is in place, use a pitch fork or shovel to expose about an inch or so of earth in each bin area. Exposing the bottom of the bin attracts microorganisms living in the soil.

Step 3: Adding Materials to Bins

Add organic matter to two bins and leave one bin empty at all times to promote faster compost production and allow turning the material from one bin to another.

Spread 4-6-inches of mixed, chopped up carbon material, the tough brown, woody materials like leaves, cornstalks, straw, shredded newsprint, paper, brown paper bags, small amounts of sawdust, vacuum contents, wood chips, clumpy grass and discarded stems from annuals pulled at the end of the season.

Add 2-to-4-inches of mixed, chopped-up nitrogen material, the green layer that includes vegetable scraps, coffee grounds, grass clippings, alfalfa, eggshells, oats, beans, bread, fruit scraps and rinds, hair, garden waste, cotton rags and strings, pond algae and non-synthetic dryer lint.

NOTE: Don’t add meat, dairy products, fat, bones or lime. Eggshells are fine, but not eggs.

If you have a large quantity of grass clippings, let them dry for a day or two before adding them to the pile. Untreated grass clippings can be added to food scraps, alfalfa hay, weeds, or hair to vary texture.

Add a thin layer of soil from the garden on top of the green layer to introduce decomposing microorganisms to your system.

Composting Tips:

  • Mix and moisten the layered sandwich of brown and green material plus soil until it feels like wrung-out sponge.
  • The layering should continue until the piles are about 3-4-feet tall in two of the bins.
  • Cover with a tarp or opened black trash bag and secure with rocks or bricks to help trap heat and activate the microorganisms and decomposers.

Step 4: Maintaining the Bins

When the bin system is set up, maintaining them is a breeze. Keep a compost bucket in your kitchen for the valuable food scraps and empty them into a bin when you turn your pile every 2-3 weeks.

You have two bins to work with, so if you want to dispose of your scraps sooner, go for it! Or you can store the food scraps in the freezer until you’re ready to turn.

For every new nitrogen/green material you add, you also want to add double the amount of carbon/brown material every time you turn the piles.

Ask friends and neighbors for their leaves to help you while diverting their organic materials from the landfill.

Step 5: Collecting the Compost

After you’ve turned the materials in your bins for a few weeks, you’ll see the raw materials have turned into a rich brown compost. Congratulations! You now have the most sought-after soil amendment money can buy.

Now’s the time to use chicken wire, ¼-inch mesh, old fireplace screen or a laundry basket to sift the compost. The compost can be as fine or as chucky as you want depending on where you want to use it and how much of it you want to use or give away.

Need Answers to Your Composting Questions?

CSU Extension-Denver Master Gardeners can answer your composting questions or direct you to other local resources: email denvermg@colostate.edu or call 720-913-5278.

Summer Tips and Tricks for Colorado Gardeners

By: Terry Deem-Reilly
CSU Extension-Denver Master Gardener since 2003

It’s June and plants are growing, mulch is in place, and we’re looking forward to a beautiful season with a successful harvest. As tempting as it is to relax right now, gardeners need to remain vigilant to keep everything perking along this summer.

Attention is the key to maintaining a summer garden. Some plants can cope on their own, but many nonnative perennials or tender annuals have problems growing in a typical hot, dry Colorado summer.

There’s no need to station ourselves in our gardens, armed with insecticides, herbicides and watering cans to attack whatever problem rears its ugly head. Just take a few minutes each day to check plants and their progress (or lack of it) to help catch problems early and to keep plants growing.

Every day or two, take a walk around your garden to look for changes in plants. Wilting, stunted growth and leaf or blossom damage may signal a plant disease or insect infestation. Hand watering can substitute for a walk, as it requires you to stop and examine foliage and flowers while bending over plants.

Pests are also more easily detected when we linger to give the soil a good soaking. We’re also likely to spot weeds, see bare spots in beds, find gaps in mulch or notice plant support systems that need filling in. On the other hand, if the plants look good, we know that we’re using the correct techniques!

Lawn Care in Summer

Given our short growing season and semi-arid climate, lawn care in the summer months presents special challenges. Consult CSU Fact Sheet 7.202, ‘Lawn Care’ for general advice about growing and maintaining a lawn.

Brown or yellow spots in the lawn are most often caused by faulty irrigation, so check that sprinklers are operating properly and applying water to all areas. If irrigation appears sufficient, make sure mower blades are properly set to a minimum height of 2 inches, according to the Lawn Care fact sheet.

“The preferred mowing height for all Colorado species is 2.5 to 3 inches. Mowing to less than 2 inches can result in decreased drought and heat tolerance and higher incidence of insects, diseases and weeds.”

Different types of turf (cool-season vs. warm-season) have different fertilizer needs as described in the Fertilizing Lawns in Spring and Summer Plant Talk Colorado article.

Information on identifying and combatting other summer lawn vexations are also provided by Plant Talk Colorado

Prevent Heat Stress of Vegetables and Small Fruits

High heat and low humidity are just two Hot Weather Impacts to Vegetables. Heat stress occurs with rising temperatures in July and August and can result in bolting, lack of fruit set and leaf scorch.

Avoid heat stress by making sure the soil in vegetable and fruit gardens remains hydrated.

Check the plants’ irrigation requirements and use the “finger test” to determine if the soil is moist or dry at a 1-inch depth. A dry soil at that depth indicates that better irrigation and/or more mulch is needed.

  • Water in the morning so plants have time to absorb water to cope with afternoon heat.
  • Avoid walking in planting beds to prevent soil compaction that slows water absorption and injures roots.
  • Water at soil level, especially for self-pollinating plants like tomatoes and squash.

Continue fertilizing as recommended for each type of plant. Apply low-nitrogen fertilizer only at the manufacturer’s recommended frequency and rate.

Harvest fruit and vegetables at maturity to stimulate more production.

CSU Extension offers many free resources with tips to help with growing almost every kind of vegetable.

To get the skinny on small fruits, check CSU Extension’s Small Fruits resource page.

Summer Care for Perennials, Annuals, Trees and Shrubs

Many perennials and flowering shrubs require frequent deadheading or shearing to keep them looking good and reblooming. Keep pinching spent flowers from annuals and fertilize roses after the first flush of blooms.

Plants in containers and hanging baskets need a good soaking at least once or twice a day in extremely hot temperatures. Check the soil in pots before watering.

Summer is peak time for insect infestations in trees and shrubs, especially those attractive to Japanese beetles. CSU Extension’s Japanese Beetles fact sheet offers in-depth information on the history and control of the pesky little devils.

Because the Emerald ash borer (EAB) continues to be a concern, CSU Extension provides details on Insecticides Used to Control Emerald Ash Borer on Residential Shade Trees.

More Summer Gardening Advice

CSU Extension-Denver Master Gardeners are available to answer all of your summer gardening questions by emailing denvermg@colostate.edu or calling 720-913-5278.

How to Lure Butterflies to the Garden

By Linda McDonnell, CSU Extension Master Gardener since 2013

A quick note of thanks for supporting last month’s Denver Master Gardener on-line plant sale. We hope the plants are healthy and productive additions to your garden and that next year, you’ll join us for an expanded in-person sale. Now, let’s talk butterflies…

Butterflies are prized for their striking appearance and graceful flight paths. A butterfly sighting in my garden is always a stop-and-appreciate-nature moment. Perhaps more importantly, butterflies are valuable pollinators and an important element in the food chain.

Painted Lady on Echinacea (Pixabay.com)

Here are five features of butterfly-friendly habitats.

Host Plants

Most butterflies require specific host plants for caterpillar development. Perhaps the most well-known butterfly/host plant partnership is the monarch and milkweed plant, Asclepias spp. (It’s worth noting that Colorado is on the edge of the monarch migratory corridor, so we see them rather infrequently.)

Two common butterflies in our state are the black swallowtail, whose caterpillar develops on parsley, dill, and related plants and the painted lady which seeks thistles, hollyhocks, and sunflowers.  Colorado State University has a list of our state’s butterflies and their caterpillar host plants here.

Food Sources

Mature butterflies seek sugary nectar for energy and nutrition and pollinate plants by moving nectar from one plant to another. An ideal environment has a season-long sequence of nectar producing blooms. Examples include spring blooming lilacs (Syringa vulgaris); mid-summer asters (Aster spp.) and Bee Balm (Monarda); native shrubs such as Rabbitbrush (Chrysothamnus nauseosus); annuals including Marigolds (Tagetes spp.) and Cosmos (Cosmos spp.); and weeds like dandelions and some thistles. Even the honeydew secretion from aphids provides sugary sustenance for butterflies.

Avoid double-petaled flowers which make it difficult for the insects to reach the nectar source. This article offers many suggestions for plant selection.

Black Swallowtail on Lantana (Pixabay.com)

Water Source or Mud-Puddle

A shallow dish with water or a mixture of garden soil and water will attract butterflies. A rock or other flat landing pad in the dish encourages drinking. It is reported that males are especially attracted to the nutrients in a mud-water cocktail. 

Sunny Open Areas and Wind Protection

Swaths of sunny plants are ideal for foraging while densely planted trees and shrubs provide shelter from harsh winds.  An ideal butterfly habitat provides both.

Insecticide-free Plants

Insecticides can be lethal to butterflies in all stages of development. Eliminating or reducing the use of insecticides will increase the populations of both the butterflies and other beneficial insects such as lady beetles and green lacewigs.

Resources and References

Colorado State University Fact Sheet 5.504 “Attracting Butterflies to the Garden”

The Denver area has two great sources for butterfly education: The Butterfly Pavilion and the Butterfly House at the Chatfield Farms location of the Denver Botanic Gardens. Both make for fun, educational outings.

June Gardening Calendar of Tasks & To Do’s

By: Jessica Harvey
CSU Extension Denver Master Gardener since 2020

June kicks off the gardening season in earnest, especially after all the spring showers we’ve been enjoying as of late. If you’ve not gotten those warm season plantings in the ground yet, now is the time! Start enjoying the bounty of blooms and get ready for all the wonderful produce on our horizons! 

Weeds & Weeding

  • All the rain we’ve been getting is great for our plants, but unfortunately, it’s also great for those weed seeds hiding in our soils. Better to get weeding early and not give them the chance to reseed again.
  • If you’ve got weedy beds that look like mine, work smarter and not harder by using the right tools. A scuffle hoe, or action hoe, in combination with a rake will make quick work of those weed seedlings and save you the tedium of hand pulling.
  • Sometimes weeds can indicate issues within the soil. Check this list of indicator weeds to see what your weeds may be telling you.
  • Once you’ve cleared the weeds, be sure to top dress with your mulch of choice to help keep those weeds from coming back again. Plus, mulching will help you conserve water as well, it’s a win win. Unsure what type of mulch is best for your garden? Check out “Selecting the Best Mulch for Your Plants” before you go shopping. 

Trees

  • There’s been a lot of spring storm damage to our trees this year and you may be struggling to get on the schedule with any of the local tree companies because of it. Use colored ribbons or spray paint at the base of broken and dead branches now when they are clearly visible, then later you won’t forget or mistake which areas are in need of attention.

Perennials

  • Check your shrubs and herbaceous perennials and trim out any branches or areas that haven’t started to show signs of leaf or bud growth. Before pruning, be sure you understand the plant you are pruning and its growth habit. For more information on when and how to prune check out PlantTalk “Colorado’s Pruning Shrubs” and CSU GardenNotes on “Pruning Flowering Shrubs.”
  • For well-established perennials, consider fertilizing now. Much like with our lawns, we need to give perennials a little love early in the season since we aren’t regularly amending their soils. If you’re unsure what type or whether you should fertilize consult the GardenNotes “Understanding Fertilizers” for guidance.

Annuals

  • Are you starting to see early buds or flowers? If so, it’s best to pinch or snip them to allow your plants to focus on vegetative growth. When freshly planted, you want your plants to focus on strengthening their root systems and putting on more foliage. You’ll see an increase in flowers and fruit later in the season for your efforts. 
  • For plants where the foliage is the focus, think coleus or basil, consider strategic pruning now to help encouraging branching. Pruning the terminal bud, or topmost growth tip, will encourage lateral buds to further develop and thereby create a bushier plant. 

Vegetable Garden

  • If you’ve not signed up yet, join the Grow and Give program to share the wealth of your harvest with those in need in our local communities.
  • If you’re already signed up for Grow and Give, let CSU Online help you get your vegetable garden off to a good start with “AGBB 2084 – Summer 2021 Free Vegetables Course”
  • Throughout the month make sure to check back on any of those climbers you may have planted and help guide them up trellises, netting or cages. Vertical plantings will save you space and helping them early will keep them from strangling other nearby plantings.

Got Gardening Questions?

Have a question we’ve not yet answered for you? Post your question at Ask an Expert or check to see if another gardener has already asked or answered the same question.

You can also reach a CSU Extension-Denver Master Gardener by emailing denvermg@colostate.edu or call 720-913-5278.