Tips for Beginner Colorado Gardeners

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

Congratulations! You’ve decided to plunge into gardening, which will improve your diet, health, property values, and mental equilibrium. Before wielding that spade and acquiring your plants, however, you’ll want to consider some facts about Colorado gardening that will ensure a productive and stress-free (well, mostly stress-free) first year. 

Firstly, Colorado is an unusual place to grow a garden. It’s at once one of the easiest and one of the most challenging locations to cultivate plants. Knowing a few facts about our growing conditions and planning to how to cope with them are the first steps in a happy garden experience. Here are the basics about our growing conditions: 

• The average elevation of locations in Colorado is 6800 feet above sea level. 
• High elevation equals intense sun and low humidity. 
• Colorado experiences drastic temperature swings, sometimes within the same day. 
• Soil is characterized by high pH and clay texture, so tilth (ability of the soil to support plant life) is poor, namely: 
  • A high concentration of calcium carbonate in our soil raises pH (ratio of acidity to alkalinity) above the neutral level of 6.0-7.0; and 
  • Clay soil contains small pore spaces, making drainage slow and limiting root growth and oxygen content. 
• Untimely, damaging snows occur in the spring and fall (remember the snow just before Memorial Day last year?). 
• Our growing season begins about May 15^th and ends around October 15^th – that’s only five months between the last frost of winter and the first frost of fall. This makes vegetable gardening particularly daunting. 

For a more detailed discussion of Colorado gardening challenges, consult the Extension Fact Sheet Colorado Gardening: Challenge to Newcomers (natives will like it, too!). 

Secondly, employing these strategies will minimize the difficulties and maximize the results in your first Colorado garden: 

• Test the soil. The CSU Soil, Water, and Plant Testing Laboratory has (yay!) reopened. Click on the link for information on preparing and submitting samples and get yours in early – the lab gets a lot of business. Results include recommendations for soil management and fertilization. 
• Amend your soil as needed. The correct amendments will add organic matter, improve aeration and water infiltration, and encourage the growth of useful organisms like bacteria, fungi, and earthworms. Use caution with manure-based composts that may be high in salt, wood chips that consume nitrogen while decomposing, and biosolids that contain pathogens and chemicals. For more details on selecting and using soil amendments, consult the Extension Fact Sheet Choosing a Soil Amendment. Bear in mind that minerals like iron and nitrogen are inaccessible to plants in our soil and must be added in formulations that the roots can absorb. 
• Apply the principle “right plant, right place” by selecting plants appropriate for our region and siting them in the proper soil and sun/wind exposures. Consider the plants’ requirements when shopping – check plant tags and catalog descriptions before making your purchases. And remember to group plants with similar needs in the same area of the garden; avoid placing roses that need regular irrigation and fertilization among native grasses that will perform nicely without either. 
• The advice given by clerks at Home Improvement Megastore notwithstanding, we CANNOT change the pH of our soil. If you’re really dying to have a holly, blueberry, or other acid-loving plant in your garden, consider growing a dwarf variety in a large container with a soil composed of planter’s mix and peat moss. (Container plants require protection or a move into the garage in winter temperatures.)  
• Mulch, mulch, mulch nonxeric plants to a depth of about two inches – this includes vegetables! 
• Water appropriately. Newly planted trees, shrubs, and perennials, including xeric varieties, require correct watering in their first summer and winter watering in dry periods. Vegetables need water at least once a day in hot weather, often twice a day if they’re grown in containers. Consult this PlantTalk Colorado™ script for some irrigation tips for trees and shrubs. 
• Use season extenders like hot caps, row covers, and cold frames to lengthen our short growing season at both ends. 
• Learn which vegetables are cool season (greens, chard) and warm season (tomatoes, peppers) and when to plant both. 
• When caught in a quandary, always, ALWAYS rely on research-based information to answer your questions; these resources are your source for science-based solutions to garden problems: 

Ask Extension (Colorado) 

https://ask2.extension.org/widget.html?team_id=1955?default_location=CO?default_county=All

Colorado State University Extension (posts and fact sheets) 

https://extension.colostate.edu/topic-areas/yard-garden

Gardening Help at Denver Botanic Gardens  

gardeninghelp@botanicgardens.org or 720-865-3575 

Colorado Gardening Calendar for March 2023

By Valerie Podmore, CSU Extension-Denver Master Gardener since 2020

These Tulips have restored my faith in spring and gardening! by Valerie Podmore

I have a confession to make. I have not been thinking about the garden much this past winter and almost thought (dare I say it) I might just pack the whole thing in. However, my eye was caught this morning by the sight of tulips starting to pop through the soil and it made me happy, and I think I have caught the bug again! So, let’s see what we can do now that we are starting to see more sunshine, and the days are getting longer. MARCH is one of the best months to prepare for the upcoming growing season, so mark your calendar to get these gardening to-do’s done in your yard and garden.

Vegetable Garden

This year I am determined to try raised bed gardening and am beginning to research what it takes to succeed. Maybe we can learn together!

• I’m starting with this article to help me figure out what to plant as a new veggie gardener.
• The raised bed method of gardening is explained in depth here. I must work to not get overwhelmed by the wealth of knowledge!
• If you are like me and have delusions of veggie growing grandeur, you will possibly have more seeds than any normal human should be allowed to have! Many of these are probably no longer viable, so best to inventory your seeds and order any you might still need.
• Last week’s post about seed starting is a timely and great way to educate ourselves on starting our plants using the DIY method.

Trees and Shrubs

• Since we’ve had so much snowfall (we’ve certainly needed the moisture!), supplemental watering is possibly not needed, but anything can happen in March so remember to water your trees and shrubs if there’s a drop-off in precipitation.
• This is a great month to prune trees and shrubs for those who want to get outdoors and “DO SOMETHING!”

Lawn Care

• If you love late winter/early spring lawn and garden care (who doesn’t love a good spring clean?) there are great suggestions in this article.
• Early March is a great time to sharpen up your mower blades and add or replace oil, clean shovels and pots, and generally tidy up anything that has been languishing in wait for warmer days.
• Late March is a great time to start aerating as long as the ground is not frozen.

Perennial/Annual Flower Beds

• While most of our garden isn’t completely awake yet, we can still take stock of what plants worked last year and what we’d like to fill in this year.
• That brings us to seeds and bulbs! See what bulbs you’ve got that can be replanted from storage; what seeds can be sprouted indoors.
• If you attended the Colorado Home and Garden Show last month (probably good that I didn’t, as I would become way too over-ambitious!), use any ideas you gained for changes you want to make.

Don’t forget to visit the CSU Extension Yard and Garden website (https://extension.colostate.edu/topic-areas/yard-garden) for more gardening tips, and yay spring!

Starting Seeds Indoors for Your Vegetable & Flower Garden

By Molly Gaines, CSU Extension-Denver Master Gardener since 2019

I became obsessed a few years ago with growing luffa sponges (Luffa aegyptiaca). I remember my grandpa growing them in Iowa, proudly tending the massive vines with long green squash, harvesting them by the bushel, peeling and drying them. But I’ve never seen luffa seedlings in Colorado, so I found my seeds online through a specialty seed website and started them inside. Luffas’ long growing season isn’t very conducive to our Colorado climate. If sown directly into the garden, they’d never mature before the fall frost.

Reasons to Start Seeds Indoors

Plants that grow best from a seedling, versus direct sowing, are the best candidates for starting inside. Focus on plants that require a longer grow time until harvest, such as heat-loving varieties. Starting seeds indoors also allows for more variety beyond what you can find in gardening centers. It also allows for more control over the early growth stages.

Cost savings is another benefit to starting seeds inside. Once you’ve invested in some supplies, it’s more economical than buying seedlings at a nursery.

Luffas require at least a 90- to 120-day growing period, so these plants are best started indoors in Colorado. Photo by Molly Gaines

Timing & Desired Plantings

Plant seeds indoors 4-8 weeks before the last spring frost date (see Growing Plants From Seed), generally considered May 5 in Denver. Review the back of seed for time to harvest. If a tomato variety requires 90 days to harvest, start the seeds inside by early April to begin harvesting in July.

Keep in mind, not all varieties tolerate being grown inside and then transplanted. Carrots, for example, do best sown directly into the garden bed.

I mostly stick to starting seeds for heat-loving vegetables and herbs that take longer to mature — cucumbers, tomatoes, some herbs and squash. As mentioned before, I also consider what varieties I can find at CO garden centers vs. varieties available only if I start the seeds myself.

Happy, thriving seedlings. Photo by Molly Gaines

Seed-Starting Supplies & Tips for Growing

Consider these supplies and growing tips:

1. Seedling containers, pots and/or trays and clear, plastic covers. I like the plastic trays with individual cells or small compostable pots. A quick Google search will also show many DIY options. Covering trays with an elevated plastic lid during germination is very helpful. Use the lid only when your trays are not in the sun or under light to avoid overheating.
2. Lighting. I plant my seedlings near a sunny window. But an overhead light, on for 12 hours a day, is best for strong, vs. leggy, seedlings. Lighting should be adjustable, always hanging about 2-inches above the plants.
3. Seed-starting mix. Usually a blend of perlite, vermiculite and peat moss/coir vs. actual soil; it needs to be loose and fluffy. When planting, poke seeds into the mix at a 1/4-inch depth.
4. Labels. Label seedlings so you can remember what was potted where.
5. Water. Keep a cup and/or spray bottle near your seedlings for spraying during germination and watering. Seeds and seedlings must be kept damp.
6. Heat. A seedling heat mat speeds sprouting. The growing medium should stay between 70-80 degrees Fahrenheit.
7. Fan. Good airflow helps prevent disease. It also helps create stronger stems.

I like this type of seed-starting medium that expand with water. Photo by Molly Gaines

Feed and Repot

You can fertilize, as needed, once the first set of true leaves on seedlings emerge. Use a diluted solution. Mix according to the fertilizer label then dilute by 1/2 or a 1/4. Don’t overdo it. If your seedlings look healthy, fertilizer isn’t necessary.

Harden Off Before Transplanting Outside

Gradually introduce seedlings to the outdoors. “Harden off” your seedlings, taking them outside and bringing them back inside for 5-7 days, each day leaving them out longer. Place trays or pots in a shady spot. Keep them well-watered.

Speaking of transplanting outside, next time I grow luffas I’ll either start them inside sooner, or plant them outside earlier. While I had a lot of fun tending to my luffas, particularly seeing the gorgeous big yellow flowers blossom (the bees love luffa flowers!), many of the gourds didn’t fully ripen. The ones that did made fabulous holiday gifts, and I loved telling people the story behind them.

My luffas, my pride and joys! Photos by Molly Gaines

Additional Seed-Starting References and Resources:

Seed Starting webinar (2022), CSU Extension, Larimer County

Starting Seeds Indoors

Vegetable Planting Guide

Emerald Ash Borer – The Scourge of the Ash Tree World – Updates Below!

By Valerie Podmore, CSU Extension – Denver Master Gardener since 2020

With spring fast approaching (can you believe we are already in the middle of February?!), our thoughts are turning to those garden tasks needed to ensure all our plants grow healthy, strong, and beautiful. Unfortunately, that includes the not so fun task of looking for and hopefully pre-empting attacks by pests intent upon killing our ash trees…you know who I’m talking about. The emerald ash borer insect, or EAB for short.

What is EAB?

Emerald Ash Borer Adult by David Capered, Bugwood.org

The emerald ash borer is an insect native to Asia, inadvertently introduced in the US in the 1990’s probably via wooden shipping pallets or packing material. This small but deadly tree predator is a green metallic beetle, the adult being approximately one-half inch long with a metallic green head and back; the abdomen is coppery-purple in color. The larvae are up to one-half inch long, have prominent bell-shaped segments and are creamy-white in color. It lacks predators to keep it in check and is now considered the most destructive tree insect pest ever to be introduced into North America and is known to kill all true ash trees.

It was first detected in Colorado in Boulder County in 2013 and even with a quarantine in place (more on that in a minute), the insect has been confirmed to have spread to Westminster and Broomfield and unincorporated Larimer County near Berthoud in 2019. The most recent confirmed detections have been in Erie (June 2021) and Thornton (June 2022). Since approximately 15% of the Colorado urban area tree population are ash tree species susceptible to being killed by EAB, it’s important to do whatever necessary to prevent this pest from spreading even more.

EAB Quarantine

In this highly informative article from 2017 “Emerald Ash Borer: To Treat or not to Treat”, the plant-pest quarantine manager for the Colorado Department of Agriculture and lead member of the Colorado Emerald Ash Borer Response Team, Laura Pottorff stated: “While we can tell you definitively where EAB is known to be in Colorado, and where treatments of high-value, healthy ash are now necessary, it’s impossible to tell you where EAB isn’t located.”

With these confirmed detections of EAB outside of Boulder County, the Colorado Department of Agriculture lifted the quarantine from that location in December of 2019, removing restrictions on the transportation of firewood and other wood supplies across counties (but don’t go crazy bringing firewood from outside your county…as they say “burn it where you buy it”). As this press release from the Department of Agriculture explains, the quarantine helped by slowing down the spread enough to allow for treatment options and or replacement of trees to occur.

So, what does all this mean for you? Since the eradication of this pest is really going to be impossible as noted in this article by The Colorado Sun, and it takes two to three years for the effects of EAB to be evident on an ash tree, it means we who live along the front range and have trees need to be vigilant and take the steps necessary to protect or replace our ash trees (I know…SAD).

Ash Tree by Gary Fultz, unsplash.com

EAB Tips for Front Range Residents

Take a look at this checklist from the Department of Agriculture:

• Determine now if you have any ash trees. Identifying features of ash trees include compound leaves with 5 to 9 leaflets; leaflets, buds and branches growing directly opposite from one another; and diamond-shaped bark ridges on mature trees. More information about ash tree identification, including a helpful app.
• If you have an ash tree, start planning. Decide if the overall health of the tree and the benefits it provides merit current or future treatment, or if it would be best to remove and replace it with a different species. If you are not sure, contact an ISA Certified Arborist. If you do plan to treat the tree, the Colorado State Forestry Service (CSFS) offers recommendations for selecting a tree-care company.
• Plant trees. Replace ash trees in poor health with diverse species. The Colorado Department of Agriculture (CDA) offers a database of registered nurseries and landscape contractors.
• Recognize signs of EAB infestation. Property owners with ash trees should be on the lookout for thinning of leaves in the upper tree canopy, 1/8-inch D-shaped holes on the bark and vertical bark splitting with winding S-shaped tunnels underneath. Report suspect trees by calling the Colorado Department of Agriculture at 1-888-248-5535 or email CAPS.program@state.co.us.

D shaped holes damage by Daniel Herms, The Ohio State University, Bugwood.org

An additional note from the Colorado State University Extension office is that drought and general urban stress of Colorado’s ash trees may mimic EAB symptoms. If in doubt, contact an arborist to know for sure.

If you want to learn even more (and let me tell you it is VERY possible to spend a good chunk of time reading about this pest!), there are great suggestions on this page from Colorado State Forestry Service, and this resource page from CSU Extension. Finally of course there is the group “Be A Smart Ash” whose website is full of information like this as just a start.

S shaped tunnels damage by Daniel Herms, The Ohio State University, Bugwood.org

While this whole subject can be disheartening, especially as we love trees and want to keep them alive for many years, the reality is that we might lose a beloved ash tree. However, with some planning and proactive care, we also might be able to continue to enjoy the beauty of these trees (or alternates) for many years to come, and who knows, maybe the EAB will experience some sort of insect pandemic that wipes it out! One can dream.

Let’s Grow Together: Becoming a Colorado Master Gardener

By Felicia Brower, CSU Extension – Denver Master Gardener since 2020

Back in 2019, I decided that I wanted to become a Colorado Master Gardener. After a decade of gardening on the East Coast and in the Midwest, I was hitting roadblocks in Colorado’s dry climate. Trial and error had left me frustrated, and I wanted to actually learn how to tackle the challenges unique to Colorado (short, arid growing season with intense sun) instead of wasting time and money trying to figure it out on my own.  

Everyone I spoke to who had completed the Master Gardener Program had glowing things to say about it, so I applied that fall for the spring 2020 program. After completing the course and volunteer hours, I can now proudly call myself a Master Gardener and feel more confident than ever about tackling our special climate. As an added bonus, I’ve also met scores of talented and knowledgeable gardeners who are welcoming and giving of their advice. All-in-all, if you’ve got the time and funding to complete the program, I recommend it.

If you’re thinking about becoming a Colorado Master Gardener, here’s what you need to know.

Photo courtesy of CSU Denver Extension

What is the Colorado Master Gardener Program?

The Colorado Master Gardener Program is a statewide community-based, horticulture training and volunteer program run by Colorado State University Extension. After completing in-depth training, Master Gardeners help the public solve their horticulture-related problems with scientific, research-based knowledge while providing meaningful outreach and educating others about how they can be successful gardeners.

Photo courtesy of CSU Denver Extension

Who can be a Colorado Master Gardener?

The Colorado Master Gardener program is available more than 40 counties! In Denver, more than 100 active Master Gardeners help with various volunteer projects all over Denver County. Denver Master Gardeners typically contribute approximately 5,000 volunteer hours and answer about 7,000 gardening questions every year.

Statewide, 1,446 Colorado Master Gardener volunteers have impacted the lives of 178,210 Coloradans with more than 45,000 hours of volunteer time.

Photo courtesy of CSU Denver Extension

When does the Colorado Master Gardener program take place?

The program happens every spring through fall. Applications go live in September for the next year’s program. After training is completed, participants must complete a required amount of volunteer hours before the end of the year. Volunteers must serve 50 hours in their first year and 24 hours each year after.​

If you aren’t able to take the full Colorado Master Gardener program, you can opt for CSU Extension’s Certified Colorado Gardener Program where you can take self-paced online courses about the following topics:

• COLORADO GARDENING FOUNDATIONS: Soils, Entomology, Tree Care & Planting, Colorado Gardening Challenges, and Irrigation
• LANDSCAPE MANAGEMENT BASICS: Soils, Lawn Care, Weed Management, Irrigation, and Tree Care & Planting
• PLANT DIAGNOSTICS: Soils, Botany, Integrated Pest Management & Plant Diagnosis, Entomology, and Plant Pathology
• GROWING FOOD: Soils, Vegetables, Small Fruits, Tree Fruits, and Entomology

You can also complete the Colorado State University Online Certified Gardener Program where you can earn a digital badge as a Certified Gardener after completing all of the online courses. You can also take any of the self-paced courses without an ongoing training commitment.

Photo courtesy of CSU Denver Extension

Photo courtesy of CSU Denver Extension

Where do Colorado Master Gardeners volunteer?

There are volunteer opportunities available for interests of all kinds. You can help out with the annual plant sale, give presentations at schools and to community groups, help out with the blog, and answer questions from community members at the Colorado Garden & Home Show and farmers markets. Volunteers can also help with the planting and maintenance of the Denver Extension demonstration vegetable garden, the Denver Children’s Home garden, and the Governor’s Mansion.

Why should you become a Colorado Master Gardener?

If you like learning about gardening and horticulture and want to help other people do the same, this is the program for you. You get to directly impact your community and help protect your local environment. It’s an excellent way to get involved, meet people with similar interests and knowledge, and find some of the best horticulture experts in the area.

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Ready to become a Colorado Master Gardener? If you live in Denver County, visit the CSU website for more details and fill out an application in September for the following spring. Hope you’re able to join us!

Colorado Gardening Calendar for February 2023

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

Photo by Gail Leidigh

This will be a brief post, as there is not a whole lot you can do outside in the yard with all the wonderful snow we have been getting. Things like winter watering and pruning are only recommended if there is no snow on the ground, and the Denver metro area is breaking records this year with continued cold temperatures and the length of time that our snow is sticking around. 

If you are looking for some garden inspiration, definitely make a plan to stop by the CSU Extension exhibit at the Colorado Garden & Home Show! The theme is “Help Your Plants Feel Good at Home in Colorado.” The educational garden will feature trees, shrubs, annuals, perennials, types of turf, as well as Plant Select® plants. This year, there will be extra emphasis on xeric plants, and each day the exhibit will be staffed by Master Gardeners from various counties. They all will be happy to answer questions and discuss your ideas for the upcoming growing season. The show runs from February 4 – 12 at the Colorado Convention Center, and tickets are available from the Colorado Garden Foundation website. 

Photo by Gail Leidigh

Besides planning and prep, February is a month to catch up on reading or viewing for fun. “The View from Federal Twist: A New Way of Thinking About Gardens, Nature and Ourselves” by James Golden, has been on my list for a little while. And I greatly enjoyed a documentary about American landscape architect Beatrix Farrand – “American Landscapes” – available for streaming on Amazon Prime. Enjoy the snow while you can; spring will soon be here!

Photo by Gail Leidigh

How to Select and Pamper Your Houseplants this Winter

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

Orchid in full bloom at Denver Botanic Gardens. Photo: Lori Williams

Houseplants are so lovely and offer a nice spot of green during the Colorado winter. Almost everyone, and certainly gardeners, can find them an enjoyable extension of outdoor gardening. Be it herbs in a kitchen window, plants brought in from summer’s patio to overwinter, or the many varieties that prefer an all-year indoor existence, research shows several health benefits of houseplants, including:

• Improve employee focus and reduced sick days in the workplace.
• Reduce fatigue and boost indoor air quality.
• Lift spirits – pops of color from seasonal plants such as amaryllis or orchids can help beat the winter blues.

As with all plants, houseplants subscribe to the maxim: Right plant, right place. Many who are convinced they have a brown thumb can work through the following simple steps, find their right plant within their (right) place and achieve success. It’s not magic, complicated, or mysterious. Promise.

TIPS FOR HOUSEPLANT SUCCESS

Proper lighting is most important. Evaluate your space and select plants that will work. Find tips for evaluating light quality here.

Most houseplants like household temps that most people like, basically around 70℉.

Some plants need more humidity than typically found indoors, so grouping those together on pebble lined trays and adding water to below the top of pebbles increases the relative humidity.

Watering is unique to each plant: Overwatering kills as many plants as under watering.  Plant tags and a quick google search can explain your plant’s preference. Grouping plants with similar watering needs together helps water accordingly. An inexpensive houseplant water meter is a handy tool, too.

Monitor consistently for pest and/or disease (and while shopping for them, too).  Look under leaves for yellowing or leaf loss. Discovering new growth can happen here, too!

Fertilize seasonally, usually during active growing months from April through September.

SELECTING HOUSEPLANTS

If you are new to houseplants, find help selecting the best ones for your lighting and skill level. This webinar is absolutely wonderful for explaining the science behind happy houseplants and selecting the right plant for your place.  

Once you’ve got a handle on the light in your space, it’s on to the fun part: Make a wish list of suitable plants and go strolling through your favorite local garden center. Enjoy the immersion in the elevated oxygen of the greenhouse, ask their staff questions, and peruse the gorgeousness you will find. 

Aesthetically, it’s fun to mix up plant structures – tall and reedy, soft and velvety, draping growth habitat, foliage colors. Are you wanting something that blooms? Violets, bromeliads, or cyclamens might be the ticket. Or is self-sufficiency key? Sansevieria, pothos, schefflera or succulents are rewarding lower maintenance options.

Another tip is to inspect plants before you buy by checking under the leaves and at the soil line. Sometimes creepy crawlies sneak their way in to even the most professional greenhouses!  

Boston fern, schefflera, and sansevieria on spa day. Photo: Lori Williams

WINTER TLC

Regardless of the time of year, all houseplants need a little TLC. During winter months, with non-melting snow, dreary skies and almost freezing temps projected for days – houseplant pampering can perk up plants and us – their peeps! Here’s how I do it:

• Gather the basics: Gloves, clippers, potting mix, a small fork or chopstick, fertilizer, watering can, and a bowl of water to keep any clippings hydrated for propagation.
• Collect plants in the shower or tub and gently spray or splash off the mid-winter dust.  It’s a nice humidity boost for them, too.
• Soak soil thoroughly and let the container drain. Clip, pluck or pinch off dead, diseased, or discolored matter. If the foliage is looking a bit limp or weak you can fertilize lightly with half strength of your favorite brand.
• Inspect plants for disease and pests. If any are present, you’ll find remedies here.
• This is a good time to select plant parts for propagating and prune to reshape foliage. Check out good tips here.
• Gently disturb the top 1” of container’s soil and apply a top dressing of potting mix. Depending on your plant’s preferred growing conditions, this can also be a good time to repot root bound varieties.
• Return the plant to its home. Every few weeks, rotate the plant so it receives even light on all sides.
• Dispose of diseased matter rather than composting it to avoid spreading the disease further. Compost temps need to reach at least 150℉ to kill pathogens which is a struggle for home compost bins to reach during winter months.

TLC for Asparagus fern – though fluffy looking, it is surprisingly thorny. Use gloves! Photo: Lori Williams

Houseplants offer a verdant element to our homes and workplaces. They are as varied and interesting as the people who share them!

Colorado Gardening Calendar for January 2023

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

January is typically a restful period for gardeners – a  time to pour over seed company websites or catalogs, review last year’s successes or blunders, set goals for the upcoming season, and investigate new gardening topics. But even though we may be ‘armchair gardening’, it is important to keep a watchful eye for issues that crop up in the landscape. Don’t forget to occasionally stroll through the garden, especially after storms, to inspect trees and plants. Take care of any issues as soon as you’re able to avoid complications later.

It’s a cold and snowy start to the new year!

Let’s take a look at recommendations for the month.

Trees and Shrubs

• We’re huge proponents of winter watering, but thanks to a sloppy, moisture-rich late December snowstorm, watering may not be needed in January. This could begin to change later in the month though, so monitor conditions with special attention to new plantings. Four weeks without sizeable moisture is the signal to drag the hoses out.

• Regularly examine trees and shrubs for snapped limbs and bark damage due to snow loads or heavy winds. This post offers tips on preventive maintenance and dealing with damage.

• Winter is an ideal time to have large deciduous trees pruned professionally. The City Forester maintains this list of licensed contractors; pointers for hiring a tree care company can be found here.

• De-icing salts used on nearby sidewalks can cause leaf scorch on evergreen broadleaf shrubs, brown needles on conifers, and damage to turf roots. Use with care.

Manhattan Euonymus (Euonymus kiautschovicus) is a broadleaf evergreen shrub prone to leaf scorch Photo: Linda McDonnell

Perennials

• Add additional mulch around perennials that are heaving or lifting up from the soil. Heaving is caused by repeated freezing and thawing, often occurs in newly planted perennials with young root systems, and can indicate compacted soil. Left unattended, it can damage or kill plants. Come spring, organic matter may be needed to improve drainage. According to the University of Iowa, shasta daisy, (Leucanthemum spp.) and coral bells (Heuchera spp.) are particularly prone to heaving.

Pixabay.com

Seeds

• Take stock of your seed stash – the prior season’s seeds may still be viable. CSU’s fact sheet on storing veggie and flower seeds has a helpful chart on seed longevity.

• While it is still a bit early to start seeds indoors, it’s not too soon to replenish seeds and supplies at a local garden center or online. Or set up a seed swap with your gardening buddies.

• If you’re new to seed starting or want a refresher, check out this blog post for a thorough tutorial so you are ready to go when it’s time.

Denver’s Recycling and Compost Programs

• Denver’s ‘green cart’ compost program rolls out citywide this month. Meat and produce scraps, coffee filters, and greasy pizza boxes, in addition to garden waste, are just a few of the tossable items. If you already participate in the program, be sure to encourage green cart newbies to give it a try.

• Have old, unused, or unwanted pesticides or herbicides hanging around? Here’s info on Denver’s program for the safe disposal of many hazardous materials  A nominal fee applies.

 Learning Opportunities

• Managing Squirrels in the Landscape on January 11th from 12-1 pm is the first in CSU’s series of virtual garden workshops. For a list of all presentations and to register, visit https://csuhort.blogspot.com/p/csu-extension-spring-gardening-webinars.html.

• The Colorado Garden & Home Show returns to the Colorado Convention Center February 4-12^th.  In addition to workshops, extensive plant displays, and vendor information, Colorado Master Gardeners will be present to answer gardening questions. Tickets available now.

• Audubon Rockies and Cheyenne-High Plains Audubon Society hosts the Landscaping for Water Realities on the High Plains conference on February 4^th.  Virtual attendance is free. Program and registration info here.

• Email garden and plant questions with descriptive photos to Denver Master Gardeners at the Denver Botanic Gardens gardeninghelp@botanicgardens.org.

• CSU’s Extension website is always available to provide science-based gardening information. It’s a good one to bookmark.

Dealing with Winter Storm Damage to Trees and Shrubs

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

Photo credit: Pixabay.com

During mild weather, we relax and admire our gorgeous lilacs and viburnums, fertile fruits, and long-lived majestic street trees. With the coming of the colder months, however, we become aware that these lovely friends are susceptible to damage and even death from sleet, high winds, and heavy wet snow. The effects of this weather are a constant concern on the Front Range, but with a little forethought and planning, they can be mitigated (if never eliminated). 

Effectively dealing with storm damage requires planning that begins when a gardener is considering installing trees and shrubs. (Minnesota Extension offers some great information on dealing with tree damage based on this principle.) However, as most readers of this blog are probably here seeking advice after a catastrophe, let’s do some time-traveling and begin with should be done (and not done) immediately following a storm and conclude with some hints for encouraging plant survival in advance of nasty weather.

This post features the highlights of emergency tree and shrub care; review the article ‘Caring for Storm-Damaged Trees’ from the Colorado State Forestry Service for more thorough guidance.

• During a heavy snowfall, brave the flakes to gently shake accumulated snow off tree and shrub branches with a broom. Lift each branch from the bottom instead of poking or shaking it. (Be prepared to do this more than once.)
• Before going out, look at the yard and street: are power lines down, are there dangling tree branches threatening to drop, or is debris or ice covering the turf or the walks? Any one of these can present a hazard to gardeners working outside. Above all, assume that any power line lying on the ground is live. 
• Examine the damage: look for leaning, broken, or uprooted trees and shrubs. Determine if there are holes and cracks in bark, trunks, or roots. Note the state of the crown (branches and foliage) of each tree; loss of more than 50% of the crown may require tree removal. 
• Leave ice coating the branches alone; it will melt as soon as temperatures rise above freezing.
• Damaged bark can be removed back to the point where healthy bark appears.
• Don’t top a damaged tree; you’ll render it weaker and more susceptible to disease.
• Avoid painting holes, wounds, or pruning cuts; the plants will seal and heal by themselves.
• Small tree branches can be removed by the gardener (see the fact sheet ‘Pruning Shade Trees’ linked below for details) but allow an arborist to remove large branches. 
• Leaning shrubs and small trees can be moved back into position, staked, and mulched.
• Wait until new growth appears to fertilize.
• Inevitably, friendly visitors bearing chainsaws will appear, offering to repair your tree and shrub damage “for less than those big companies.” These are the horticultural equivalents of gypsy roofers who show up after hailstorms. They are usually untrained and not covered by workers’ compensation or liability insurance.

Now, let’s examine how we can minimize storm losses with some deterrence.

Mitigating plant damage begins with asking what genera, species, and varieties of trees and shrubs display less vulnerability and more resilience in the erratic Colorado climate. Luckily, the ready answer is (drum roll……) native and adaptive plants. Plants that have evolved in montane, submontane, or plains environments will rebound from weather damage much more quickly and thoroughly that those imported from dissimilar growing conditions. Plan for resilience by selecting trees and shrubs recommended in these resources: 

• Native Shrubs for Colorado Landscapes
• Native Trees for Colorado Landscapes
• Front Range Tree Recommendation List
• Tree Selection: Right Plant, Right Place
• Plant Select

Once plants have been selected, practice proper siting and planting. Again, we’re assisted by Extension and Plant Talk resources:

• Preparing the Planting Site
• Tree Placement: Right Plant, Right Place
• Planting Trees and Shrubs

Proper cultivation and integrated pest management (IPM) are indispensable to plant health, as outlined in these publications:

• IPM and Plant Health Care
• When to Fertilize
• Watering
• Pruning Shrubs
• Pruning Shade Trees

For information on specific plants, diseases, and pests, review the resources on subjects from “abnormal and distorted plant growth” to “Zimmerman pine moth” included in the Extension page Online Gardening Publications (Trees and Shrubs). 

Fans of Gardener’s Supply Company should check out the great discussion of winter damage prevention on their website.

We hope that this is helpful in the present emergency and beyond – but, as always, Denver County Extension is eager to help with all problems and concerns!

Taking Another Look: Indoor Evergreens for Good Health

To close out the year, we’re bringing back this popular post from 2019. It’s a timely reminder of the power of plants to contribute to our well-being while beautifying our environment.

We’re taking a short year-end break and will be back with new posts in January. On behalf of all the blog contributors, happy holidays!

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Indoor Evergreens for Good Health

An evergreen wreath on the front door and a real tree in the family room are conventional decorations for the holiday season. So are those beautiful winter containers filled with evergreen branches sitting on the porch.

But evergreens are much more than outdoor decor.

When placed indoors the greenery adds to the holiday scenery, but it’s that fresh scent that makes them indispensable.

Just like walking in the forest and “forest bathing” are therapeutic, using evergreens indoors is beneficial, too. Evergreens give us a healthy dose of phytoncides when we take a deep breath. These wood essential oils are the same airborne chemicals that trees and other plants give off in nature.

Pine scents and forest atmospheres not only remind us of the holidays, but they benefit our health physically, mentally and physiologically, according to the Michigan State University Extension.

CLICK HERE TO READ THE FULL POST

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