Category Archives: Trees

Dealing with Winter Storm Damage to Trees and Shrubs

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

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: 

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

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

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!

Colorado Garden Calendar – December 2022

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

Gardening slows down in December but doesn’t stop completely. There’s still time to finish some chores from our November list, so be sure to revisit it. For the next few months, prioritize winter watering during dry spells to ensure healthy plants next year.

December’s also a great time to enjoy indoor plants, appreciate nature’s seasonal beauty, and start thinking about next year’s garden.

Here’s a run-down of tasks and activities for December.

Trees, Shrubs, and Perennials

  • Winter watering is essential to long-term plant health – make it a point to water during four-week dry stretches. To ensure proper absorption, water early in the day when temperatures are above forty degrees. This post offers excellent advice on when, why, and how much to water – and photos of the impact of too little moisture.
  • To help with moisture retention, replenish mulch in areas that have gotten thin.
  • Shake snow from bent tree limbs and branches to avoid breakage and lightly prune any broken limbs to avoid further damage.

Compost

  • Continue adding green and brown materials to your compost bin. Since decomposition is slower in cold temperatures, break your materials into smaller pieces to speed up the process. The University of New Hampshire offers more winter composting tips here.

Houseplants

  • Winter is the dormant season for non-blooming indoor plants. Reduce watering, stop fertilizing, and keep them away from drafts for the next few months.
  • Increase humidity around your plants. Ignore popular advice to mist with a spray bottle – to make an impact you’d need to mist for hours on end! Instead, group plants together on a pebble-lined tray and add water to just below the top of the pebbles.
  • Check regularly for pests such as mealy bugs and spider mites. If present, treat and quarantine the infected plant. Find remedies here.
  • ‘Tis the season for holiday plants and live Christmas trees. Here are some helpful links to keep them at their best: Keeping the Ho Ho Ho in Holiday Plants, Tips for Caring for Your Christmas Tree, A Year in the Life of an Amaryllis, and Christmas Cactus Care.

Celebrate, Inspire, and Explore

  • The winter solstice arrives on December 21st. In the Northern Hemisphere, it marks the day when the sun is at its lowest height at noon as well as the shortest day of the year. Starting the next day, we’ll gain about two minutes of daylight daily till June 21st. Yippee!
  • Share your enthusiasm for gardening with a child – find a few activities here or wander the library aisles to find an inspiring book on plants or nature.
  • Check out 2023 seed introductions from your favorite growers. It’s time to start scheming and dreaming about next year’s garden.

As always, CSU is available to help with gardening advice at the CSU Extension Yard and Garden website. We hope you’ll visit often.

We’ll be back in two weeks with our last post of the year. Until then, enjoy all the season brings.

Colorado Gardening Calendar for October 2022

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

It’s Pumpkin Spice time…no, not the drink, the gardening season! October is one of the best months for cleaning up the garden in preparation for the impending end of the season and of course doing pumpkin things! Mark your calendar to get these gardening to-do’s done in your yard and garden.

Vegetable Garden

  • Continue to harvest your vegetables which you planted both earlier in the season and in early fall.
  • Think about building cold frames or some sort of protective covering to help your veggies last as long as possible with the colder weather this month.
  • Cover crops can help build your soil for next year’s planting.
  • If (unlike me) you have kept your herbs alive this season, maybe give herb preserving a try.
  • Take a look at this article about Pumpkin Habanero peppers…talk about Pumpkin SPICE!

Trees and Shrubs

  • Young trees’ trunks (2” and less) will need to be wrapped to protect from sunscald in winter (from November to April).
  • Pay attention to watering, making a plan to water deeply every 4-6 weeks during dry fall and winter months.
  • More detailed tree and shrub care information can be found here.

Lawn Care 

  • Lawn aeration can still be performed early in the month.
  • Because we can have our first frost of the season anytime this month (average first frost is around October 6th), this is time to winterize your sprinkler system. Good advice even if you don’t do this yourself. 
  • Oh hooray! LEAF CLEANUP.
  • In addition to the above, here is the Leaf Drop information for 2022 in Denver.

Perennial Flower Beds 

  • If you didn’t plant any spring blooming bulbs yet, get ‘er done this month! 
  • Early in the month is a great time to divide and transplant summer blooming perennials before the cold moves in.
  • Here is a great pollinator-friendly post on fall garden clean-up if you are looking to help our friends through the winter.
  • Working on winterizing your plants will help them survive for next year’s growing season.

Annual Flower Beds

  • Pansies are a great way to get late season color into your garden.

Other Tasks

  • Houseplants that were outdoors will want to come back in when the nighttime temps fall below 50 degrees. Make sure to give them a good clean-off of creepy crawlies before bringing them inside!
  • Clean your tools for next year.

As always, visit the CSU Extension Yard and Garden website for more gardening tips.

Colorado Gardening Calendar for SEPTEMBER 2022

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

Let’s not get downhearted at the impending end of growing season! September is one of the best months for continuing harvests, enjoying our gardens, and yes, preparing for the end of summer (sad face). Mark your calendar to get these gardening to-do’s done in your yard and garden.

Vegetable Garden

  • Continue consistent watering practices. We might be cooling down, but we are still dry, so don’t let your hard work “die on the vine!”
  • Plant fall vegetables! Some do really well in cooler weather and ripen quickly for harvest, such as lettuce, kale, arugula, Swiss chard, and spinach which can be direct seeded.
  • Save heirloom plant seeds if you are looking to start your own plants for next season.
  • Get your plant covers at the ready just in case we have a (pretty typical) cold snap or just in case temperatures dip lower than your veggies enjoy.
  • Make sure to clear away any dead vegetation to prevent disease or pest proliferation.

Trees and Shrubs

  • Water, water, water! Just like our vegetable gardens, our trees and shrubs need to be consistently watered. Weekly is a good schedule, but this fact sheet provides very thorough advice.
  • Trim only branches or limbs which are damaged or diseased at this time.
  • Be careful with fertilizing trees and shrubs. This link has good information on fertilization if there’s been particularly dry weather (when is it not?).
  • While planting in fall might not be the #1 time, it’s still possible to find discounted plants and if you finish before the end of October, your tree or shrub will have some time to establish itself before the cold of winter.

Lawn Care

  • Aerate this month to allow oxygen to get to the roots of your grass. This is an awesome turfgrass post for more information.
  • Water deeply, giving your grass a good, long drink. Weekly for even 45 minutes is more beneficial than more often for less time.
  • This great fact sheet has probably everything you need to know for keeping your lawn healthy.
  • While the scourge of Japanese Beetles might be behind us, this is a prime time to apply grub-killers like grubGONE! and GrubEx to turf to help prevent them returning.

Perennial Flower Beds

  • Water (I know, it’s like déjà vu!) weekly until the ground freezes to give the roots a chance to develop before winter.
  • Cut back spent plants but consider leaving some stems and seed pods in place for pollinators and birds. This post from our Routt County Extension friends posits a different way of thinking about cleaning up (or not!) the season’s leftovers.
  • Look at what needs filling in or doesn’t work and make plan for spring.
  • Purchase fall planted bulbs – who doesn’t love plant shopping? This is the time that plant stores, catalogs or online sellers are stocking up so go crazy!

Annual Flower Beds

  • Clean up annuals in containers and sanitize any pots you’ve emptied.
  • Get some fall color such as chrysanthemums or pansies which overwinter quite well if mulched properly.

Other Projects

  • KEEP WEEDING! That is all.
  • Start prepping houseplants that have been outside to come back inside for winter. Check out this post for details.
  • Finally, this is the month when Colorado Master Gardener program applications will begin! These will be posted on our main website with applications open September 1 – October 16. Do you or someone you know want to apply? Please DO!

Visit the CSU Extension Yard and Garden website (https://extension.colostate.edu/topic-areas/yard-garden) for more gardening tips.

Looking Forward: A Lower Maintenance Garden with Native Plants, Fruit Trees, and Shrubs

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

Now that the 2022 summer season is winding down, it’s a great time to review what worked in the garden and what didn’t and to start planning for next year. (Keeping a garden journal throughout the season saves time and makes this much easier!)

Start by asking yourself the following questions:

  • What grew well this season?
  • What didn’t grow as well as you would have liked? Any idea why?
  • Did you struggle with pests or disease?
  • What do you want to plant next year?

After you have the answers to those questions, you can begin to make a plan to fix any problems that popped up or to repeat your successes next season.

As far as what grew well in my garden this year goes, I planted more localized seeds this year because seeds bred for our specific climate tend to have fewer days to maturity and produce more drought-tolerant plants than ones grown from other seeds I’ve used. They fare better in my garden and will be a staple every year moving forward.

That being said, my garden got off to a rough start this year thanks to pest problems, extreme heat, and watering issues. Many of the seedlings I started inside were immediately eaten after being transplanted outdoors, and it seemed like no amount of diatomaceous earth could help. I wasn’t watering enough to combat the weeks of 100° sunny weather, and the growth of a lot of my vegetables suffered because of it. I was recently able to get things under control (better late in the season than never!) and my vegetables and flowers have finally started growing the way that I had hoped they would. I’ll be spending the winter learning more about Integrated Pest Management (IPM) and effective watering techniques to make the most of water during a drought.

As I look at what I’d like to change in my garden next summer, one big one is that despite loving it, I want to spend less time doing maintenance in it. I spent much more time weeding and trying to problem solve than I would have liked, and a few adjustments could make a very big difference.

The biggest change is going to be adding more native herbaceous perennials and fruit shrubs and trees in the yard. My hope is that by making the investment to fill out those open spaces, the weeds I spent so much time pulling will be unable to take over, and I’ll end up with beautiful, lower-maintenance native flowers, shrubs, and trees.

Here are a few of the plants on my list for next year:

FLOWERS

I usually plant vegetables and annual flowers, but after seeing the perennials that I planted last year pop up this year without having to start anything inside, I’m making a big shift to focus on native flowers and herbs that come back without any effort from me.

Having perennials show up in the spring will add much-needed greenery to the yard after a cold winter, and I look forward to the pops of color they’ll provide throughout the summer and into fall. I can’t get enough of the vibrant red and yellow petals of blanket flower (Gaillardia aristata) and plan on adding some big patches of it to my garden next year. I’ll also be looking into adding more penstemon (Penstemen spp.) to the landscape. With more than 60 native penstemons to choose from, these easy-growers range in size from a few inches to a foot or two tall with long flowering spikes.

Chocolate flower’s (Berlandiera lyrata) yellow daisy-like flowers have a wonderful scent and typically flower from June until frost. Goldenrod (Solidago spp.) produces tall bursts of yellow blooms later in the summer, from August until November and is known for being easy to grow and care for.

SHRUBS

Shrubs, specifically ones that produce fruit, are going to take a lot of space in my yard next year. Drought-tolerant gooseberries and currants grow especially well in our area, and their berries can be eaten fresh or used to make delicious jams and pies.

I have a raspberry patch that I plan on expanding to different areas of the yard. These prolific growers will take up a lot of space and provide delicious snacks while I’m out harvesting and fresh berries for some new recipes I want to try. Serviceberry is cold-hardy and drought-resistant, making it a no brainer for someone looking for a low-maintenance addition to the garden. The fruit also happens to be high in vitamins and is comparable to blueberries but with a slight apple flavor.

TREES

Trees are a big investment and a lot of planning needs to go into which trees will be planted and where. For fruit trees, I’d like to plant plums, since they’re considered very dependable for this area, and a peach tree. Peaches can be a higher risk tree because late frosts can damage blooms and prevent peaches from developing, but I think it’d be fun to have a self-fruiting dwarf variety that can still provide shade and habitat for animals even when it’s not fruiting.


After planting all of the fruiting trees and shrubs, I’ll have an abundance of produce in my yard for years to come that I’ll be able to preserve and share with neighbors and members of my community through programs like Grow & Give. It’ll take a few years, but after everything’s established, I’ll only need to worry about planting my vegetables annually, which I also plan to scale back on…eventually. For now, my focus is on finding the plants that I want to get in the ground this fall and next spring, filling out the landscape, and learning as much as I can about how to help everything in my garden thrive.

Watch for future ‘Looking Forward‘ posts where we’ll spotlight Master Gardeners who are applying what they’ve learned to expand, rethink, or improve their gardens.

Colorado Gardening Calendar for August 2022

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

The dog days are upon us, but with any luck, our gardens are still perking along without much assistance from us humans. With heat and drought still afflicting the plants, however, there’s still some garden mindfulness to practice before winding things down for the year.

WATERING

Nonxeric plants still require an inch to an inch-and-a-half of water each week in the August heat; without substantial rainfall, we’re stuck with manual or machine irrigation to keep gardens going for the time being. If our monsoon does kick in, inserting a water gauge in the garden to measure weekly precipitation totals will help limit irrigation to the proper amount for the season.

Keep an eye on sprinkler-system performance. Sprinklers should be sending water to plants and turf, not onto sidewalks, and amounts should be sufficient to dampen soil to a depth of four to six inches.

Check mulch to make sure that it’s still covering plant roots; it can be dislodged over time by humans, critters, and/or irrigation. Consider acquiring an extra bag or two (or more!) for use in the fall.

Discouraged by plants drooping in the heat? Don’t grab the hose and soak them immediately; if the soil around them is moist and mulching is sufficient, they have adequate moisture and should recover in cooler nighttime temperatures. And recent research on plants’ coping mechanisms when under stress will have a nice calming effect on the mind.

FERTILIZATION

Feed tomatoes, squash, and other flowering vegetables with low-nitrogen fertilizers as prescribed by their labels to promote continued fruiting. Don’t despair if production slows; fruit usually won’t set when temperatures exceed 80 degrees.

Feed roses for the last time in mid-August to prevent the growth of tender shoots that can be blasted by early frosts. Late-flowering perennials will appreciate feeding with slow-release organics through early fall. (Fall dieback of herbaceous perennials is part of their life cycle, so frost damage on new growth won’t be a concern.)

WEEDING, HARVESTING, AND DEADHEADING

Keep after the weeds! They’ll continue to grow and set seed for next year if they’re not removed.

Continue to harvest ripe produce and clear a patch for a fall crop of cool-season plants like lettuce, radishes, and spinach – these can be seeded in mid- to late August. CMG GardenNotes #720 contains cultivation pointers for hardy and semi-hardy vegetables in Colorado. (Buy row covers and other protection from early frosts this month so you won’t get caught by the inevitable surprise September freeze.) Avoid the end-of-season rush by removing and composting healthy plants that have ceased fruiting.

Keep deadheading roses but gradually stop removing blooms to promote dormancy. If your roses make hips, this practice will also allow hip formation before frost.

PESTS AND DISEASES

Japanese beetles may have mainly disappeared by now, but August and September are prime months for applying grub-killers to turf. Get a start on control for next year by using products like grubGONE! and GrubEx.

Late-summer pests will annoy until cold temperatures kill them off or force them into hibernation, so check out this science-based advice from The Burlington Record for Front Range gardeners. July and August heat boosts development of powdery mildew and other plant and turf diseases; consult these Extension fact sheets for the lowdown on symptoms, causes, and remedies for the most common plant and turf disorders.

PRUNING

Taking out dead, diseased, and dying branches and canes is always in order – but take a look at this general guide on when to prune before wielding those Felcos. The general rule is to prune spring bloomers right after flowering, and summer and fall bloomers in spring.

Roses are happy with pruning in late April or early May. Many gardeners earmark this task for Mother’s day weekend, which is usually past the average last frost of the season. Find more on pruning roses here.

Hold off on pruning most trees until late winter, with four exceptions: maples, birches, walnuts, and elms – these “sappy” trees appreciate having their grooming in August.

PLANTING

Can gardeners plant trees, shrubs, and perennials in late summer? Absolutely, provided they do three things: select larger plants with good root systems, install them during the cooler parts of the day, and provide mulch and sufficient irrigation to establish them before the ground freezes (usually in mid-October at the Denver elevation). Nurseries will shortly begin their sales, so visit a few to see what you fancy.

Whatever you choose to do this month, County Extension offices are eager to help with your problems; give yours a call anytime!

Colorado Gardening Calendar for June

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

So, who had the fifth earliest 90-degree day and the eleventh latest spring snowstorm in May on their garden bingo cards last month? Well, it’s June and who knows what else Mother Nature will throw at us! 

Thank you to those who attended the CMG Plant Sale during the great snowstorm of May 2022. Likely, you’ve either have planted your new purchases or will be doing so soon! 

JUNE is one of the best months for being happy that we can go outside into our gardens and watch (or MAKE) them grow. Mark your calendar to get these gardening to-do’s done in your yard and garden.

Vegetable Garden

  • If you’ve planted your cool season-veggies (peas, lettuce, kale, and spinach) last month, this is the time to harvest to prevent these going to seed.
  • Warm-season plants like tomatoes, peppers, and eggplant will thank you for continuing to transplant them this month to keep your harvest going.
  • Water evenly, close to the soil rather than overhead to prevent fungus and other plant diseases from forming.
  • Don’t forget to continue to perform the most fun activity ever…WEEDING! You don’t want your lovely veggies having to compete with these evil garden monsters.
  • Apply organic mulch to keep the moisture up and the weeds down. Untreated grass clippings (i.e., chemical-free) are a good option.
  • Make sure to join the Grow and Give program which supplies fruits and veggies to folks in our local communities who might have a need for our extra bounties.

Trees and Shrubs

  • If there has been no precipitation in a month, make sure to water your tree(s). Trust me even with the recent snow, we are still very dry.
  • If you are thinking of doing more xeriscaping, take a look at this information sheet on trees, remembering that less water for the landscape means less for trees and shrubs as well if we don’t set up the landscape in a water-wise way.

Lawn Care

  • As mentioned in last month’s calendar blog, Japanese beetle control at the grub stage by using products like GrubGONE! that contain bacillus thuringiensis var. galleriae (Btg) must be applied to turf in May and early June to take effect. Check with a local nursery regarding availability of these products or order them online. Consult this Extension fact sheet regarding Japanese beetles for advice on dealing with this pest throughout the summer.
  • This information sheet gives great information on watering during a drought, which we are experiencing even with late moisture we received.
  • This might be a good time to start looking at more xeric plants as mentioned above in the tree/shrub section. Colorado and the west are getting dryer and we could look at different ways to reduce our water use including cutting back on traditional, high water needs lawns. Watch for our upcoming blog post on this topic, too.

Perennial/Annual Flower Beds 

  • Our perennials require good watering during the month, low-level, slow watering to prevent fungus and other plant diseases caused by over-head watering. This applies to annuals as well, whether in containers or beds, to prevent them from drying out.
  • Dead heading (the practice of removing spent blooms) will keep new flowers blooming throughout the month.
  • If you have iris plants that have been in place for 3-4 years, consider dividing them after they finish blooming to keep them growing strong…kind of like us cutting our hair!
  • This article contains a trove of information on creating and maintaining a perennial flower bed.
  • Low-water flowering plants information (for both perennials and annuals) can be found here. An awesome read!

In closing, as June is Colorado Pollinator Month, take a look at this post on how we can attract these very important animals to our gardens.  Also visit the CSU Extension Yard and Garden website for more gardening tips.

Tree Pruning Basics

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

Late winter and early spring are ideal times to assess the pruning needs of deciduous trees that are at least two years old. Taking the time to structurally prune young ornamental, shade, and fruit trees that are in their lifecycle’s “growth phase” will improve the tree’s structural integrity and will help extend its life by making it more resilient to harsh conditions.

In snowy climates like Colorado, storm damage is extremely common, occurring frequently to trees with codominant trunks (adjacent trunks of similar diameter). When a tree has codominant trunks, breakage at the branch union or crotch (the V shaped area formed by the codominant trunks) is likely. The branch union breaks because it has not developed a branch collar (the area where trunk wood wraps around the tree branch). A strong branch collar strengthens limbs and enables the trees to sustain the weight of snow and fruit and resist breakage from the force of strong winds.

Helpful Tips

A general rule of thumb is to prune limbs that are 2” or less in diameter. To accomplish this, you’ll need hand pruners and loppers, and possibly a hand saw. Pole pruners will assist with reaching higher branches providing they are sharp enough to make clean cuts. To avoid spreading diseases, it is important to keep tools clean and sharp.

There is no need to apply dressing or sealant to freshly cut areas. This is a bygone practice which can interfere with growth and can even contribute to decay.

Trees that are stressed and showing little growth should only have dead or damaged branches removed. 

Guidelines on how much to remove from a tree at one time depend on the tree’s age, species, and condition. Mature trees, (trees that have reached greater than 75% of their mature size) can have 5% to 10% of their live wood removed.

Medium aged trees can handle a pruning dose of 10% – 25% of live wood. The medium phase of a healthy tree’s life is a period of active growth and is not determined by tree species or chronological age. Active growth rate can be determined by looking at multiple branches around the tree and the distance between the buds. CSU offers more information on assessing a tree’s growth rate, age, and recommended amount of pruning in Garden Notes #615, starting on page 3.

For safety and practical reasons, CSU recommends leaving the pruning of large and mature trees to   arborists who are certified by the International Society of Arboriculture (ISA). You can find ISA credentialed arborists on this helpful list of contractors published by the Denver Forester.

Pruning Steps

The following are steps for successfully pruning small deciduous trees.

  1. Prune dead, diseased, or damaged branches. Be sure to remove branches that cross or rub to prevent wounds from forming. 
  1. Support growth of a strong lead trunk. Remove any competing (codominant) trunks that are starting to develop. If the main trunk has died or become damaged, select a side branch to become the new leader and then, overtime, remove its competition.
  1. Establish the desired height of the lowest branch. Generally, shade trees should have higher clearance to allow people and vehicles to move beneath. Ornamental or specimen trees in garden beds can have lower branches, but still consider the height of the lowest branch.

For tree strength, it is recommended that the lowest branches start about one-third of the way up the tree, the middle third should have the most volume and width, and the top third should taper off to the top.

  1. Develop branching structure. The side branches should be less than one third to one half the diameter of the trunk. If a branch is growing too fast in relation to the trunk size, it can be trimmed by one third to two thirds of its length to slow its growth.
  1. Manage temporary branches. These are branches on the lower trunk which help with growth on very young trees. As a tree matures, these branches are no longer beneficial and should be trimmed and removed over time. 

You may find this CSU video helps you to visualize some of these pruning techniques.

Additional Resources

There are many more resources available to help you learn to confidently prune your trees. Here are additional links that you may find useful.

Why Prune Shade Trees? PlantTalk Colorado #1721.

The Science of Pruning. Colorado State University Extension Master Gardener Program.

Pruning Landscape Trees and Shrubs. University of Florida – IFAS Extension.

Pruning Mature Fruit Trees. PlantTalk Colorado #1210.

Recommended Trees for the Colorado Front Range Community: A Guide for Selecting, Planting and Caring for Trees. Published by Colorado State University, Colorado Tree Coalition, and the US Forest Service.

Tree Pruning Techniques. New Mexico State University.

Colorado Gardening Calendar for March

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

MARCH is one of the best months to whine about WHY ISN’T IT SPRING YET? then calm down, realize it’s almost here and daydream about sunny days in the garden. As I write this, there is still snow on the ground and more in the forecast (which is awesome sauce for our outdoor plants) but if you are like me, the instant March hits you think it’s time to get outside doing garden things. Slow down there cowboy, technically it’s still winter and there’s more planning and prepping to be done. Mark your calendar to get these gardening to-do’s done in your yard and garden.

Vegetable Garden

  • Time to get your project management hat on and plot out your garden. You’ll find a plethora of landscape design apps online or you can use good old paper and pencil.
  • Inventory your seeds and order any you might still need as well as any supplies for seed starting
  • Cold tolerant veggies can be started in a cold frame or possibly outdoors if the daytime temperatures are consistently 40 degrees F or above – so pretty much the END of March.

Trees and Shrubs

  • If precipitation is sparse (4 weeks without moisture), remember to water your trees and shrubs.  While we are doing well moisture-wise this year,  we know things change quickly in Colorado!
  • This is a great time to prune summer flowering shrubs and dormant/shade trees. However, refrain from pruning early flowering shrubs such as spirea, lilac, and forsythia because they bloom on last year’s growth. 

Lawn Care 

  • Early March is a great time to sharpen up your mower blades (try to contain your excitement!) and add or replace oil if applicable.
  • If the ground is not frozen and your landscape not too dry (i.e. LATE March), you can aerate, which is the process of poking holes in the lawn and supplying the grass with air.

Perennial/Annual Flower Beds 

  • Just like your veggies, get your seeds in order and ready to start them sprouting indoors.
  • Check your bulbs and tubers in storage and think about what bulbs you can plant in spring for summer blooms.
  • As with February, take stock of your current beds to see what might be lacking and needs new life. 
  • Don’t worry too much about late season snow, as snow serves as an insulator on perennials that have broken dormancy and won’t harm plants.
  • If you attended the Colorado Home and Garden Show in February, use the ideas you gained to plan for any changes you want to make. However, remember the motto of “right plant, right place” when planning your new additions.

Finally, (the bane of my current existence) review structures and hardscape, paying attention to needed repairs or changes. With luck this year my money tree will bloom profusely and help me pay for everything! 

Don’t forget to visit the CSU Extension Yard and Garden website for more gardening tips…and happy gardening!

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!