Colorado Gardening Calendar for May and 2022 Denver Master Gardener Plant Sale

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

May is the month when gardening really goes into high gear! Here are the areas and tasks to tackle this month:


  • Veggies and herbs can be planted this month; be prepared to cover them if nighttime temperatures go below 40 degrees. It’s advisable to plant tomatoes when overnight temperatures are consistently above 50 degrees.
  • Start weeding now, in all areas of the garden. Get ‘em while they’re young!
  • Find hints for combatting vegetable pests in this list of CSU fact sheets.


  • Make sure that hoses and sprinklers are in good condition; apply an inch of water to the lawn each week, except during rainy periods. Denver Water has some excellent suggestions regarding lawn irrigation and general care from May 1st through September 30th, when watering restrictions are in effect.
  • Consider irrigating the lawn at night or in the early morning hours when evaporation is minimal. This can be a real turf AND water-saving measure in the hotter months, and it won’t promote diseases.
  • Set mower blade height at two inches – higher grass keeps the soil moist and promotes good root growth.
  • A thick thatch layer interferes with efficient watering and fertilization, so check for thatch and arrange for power-raking if the thatch is at least one-half inch thick.
  • Products like GrubGONE! that contain bacillus thuringiensis var. galleriae (Btg) as a control against Japanese beetle grubs 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.
  • How lawns are watered, mowed, cultivated, and fertilized in their early growth will determine their appearance and health throughout the summer and fall (and perhaps for the next year as well). This fact sheet on lawn care outlines the best practices for tackling these tasks from now until fall.


  • Take a look at the garden to spot any “holes” that can be filled with a good-looking shrub, rose, or small tree – right now is when nurseries have the best selection. Be sure to call the Utility Locator Service at 811 before digging any large holes.
  • Begin watering existing trees and shrubs deeply once a week and check to ensure that plants are well-mulched. Here’s helpful information on selecting the correct mulch for your plants.
  • Start checking for pests; they will become more active as the weather warms and our spring rainfall commences (we hope). Consult this list of CSU fact sheets for information on specific insects and controls. When selecting pest controls, consider their effects on beneficial insects!
  • Now’s the time to apply copper spray to susceptible trees such as apples, pears, quince and crabapples, to prevent fire blight.
  • Finish spring fertilization and pruning of roses; make sure to apply two inches of mulch at the base of each plant and water newly planted roses twice a week for the first two or three weeks to promote root growth. Once established, roses will appreciate getting at least an inch of water weekly as temperatures rise.


  • Perennials can be hardened off and planted now; wait until at least the last average frost date in mid-May to fill annual beds and containers. Keep frost covers handy if we have one or two chilly nights before Memorial Day.
  • Summer bulbs can be planted now, so check them out at your local nurseries. It’s also a great time to divide summer and fall blooming perennials, find excellent info here.
  • Treat pollinators by seeding bare spots with their favorite annual plants, including borage, dill, zinnia, and/or cosmos. Plant as recommended by the seed packets and water. Seeds will germinate in a week or two; sprinkle the seedlings gently every few days and wait for the bees and butterflies to arrive! More pollinators mean more tomatoes, squash, fruit, etc., etc.

May certainly is a busy month in the garden! What’s on your to-do list?

When and How to Prune Your Flowering Woody Shrubs

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

Happy Earth Week, readers! In this post we’re taking a look at pruning woody flowering shrubs – a task that is sometimes misunderstood or easy to put off. However, with a bit of effort, you can improve the vigor, health, pollinator allure, and enjoyment of these plants. Here are some helpful tips.

Woody shrubs typically have multiple branches which emerge from the ground, retain their shrub-like shape after shedding their foliage in the winter, and are 12’ tall or less at maturity. New growth re-emerges in the spring on the existing branches. Woody shrubs are unlike herbaceous perennials, which die to the ground each winter and send out new growth from the ground each spring.

The key to knowing when to prune is whether the shrub flowers in the spring or the summer. Yep, it really is that simple! I made a whole bunch of pruning mistakes myself before learning the difference, and the CSU Extension website was a wealth of information to me as a novice gardener. 

Spring-flowering shrubs bloom on new growth from the previous year. In other words, it blooms on branches that grew during the summer and fall after it finished blooming the prior spring. This means that if you prune during the fall, winter, or early spring, you will be cutting off that new growth with potential buds. Therefore, the best time of the season to prune a spring-flowering shrub is shortly after it finishes blooming. This post-bloom pruning can help shape, remove dead branches, increase flowering the following year, and maintain the plant’s size.

Common spring-flowering shrubs:

  • Lilac
  • Forsythia
  • Viburnum
  • Beauty bush
Fall shearing of this spring-flowering lilac removed flower buds on the lower section of the shrub. Did I make a similar mistake a few years ago? Most definitely. Source: CSU Extension GardenNotes

Shrubs that flower in the summer bloom on new growth that happens in the spring season, so they can be pruned during dormancy in the winter and early spring without affecting the blooms, and the pruning may actually stimulate desirable growth. 

Common summer-flowering shrubs:

  • Hydrangea (Colorado-hardy types, such as “Pee Gee,” or “Annabelle”)
  • Butterfly bush
  • Rose of Sharon
  • Blue Mist Spirea

This CSU handout contains an expanded list of woody plants with pruning advice. CSU’s Colorado Woody Plant mobile app also contains a wealth of helpful information.

Both spring and summer-flowering shrubs can be pruned with the goal of encouraging new growth using thinning or rejuvenation methods, which are best to complete during the dormant season of late winter/early spring. These techniques are particularly effective for older shrubs with lots of dead wood.

Thinning is the selective removal of older canes that allows for more sunlight and air circulation and stimulates the growth of new shoots. Up to one-third of the oldest wood in a shrub can be cut to the ground. Thinning helps with some insect and disease problems, such as lilac ash borer and powdery mildew and encourages more blooms. This method can be time consuming, but it is time well spent if you are able.

Rejuvenation pruning is cutting a plant back to the base, which is quick and easy to do while getting maximum results. This prompts the shrub to regrow from its roots and act like a young shrub again with lots of blooms and a smaller size. This should only be done every 3 – 5 years after the plant starts to look leggy and overgrown. One drawback to dormant season rejuvenation pruning is that you will have to wait another year for spring-flowering shrubs to bloom again. 

Sheared forsythia in full bloom. Shearing does not encourage new wood. Source: CSU Extension Garden Notes

An unfortunate pruning technique that can be seen just about everywhere you look is the shearing of a shrub into a ball or flat-topped shape. This is undesirable for most types of plants other than formal hedges. Shearing causes thick growth on the outer most parts of the shrub, which then blocks light to the inside and underside leaving the interior woody and prone to weather damage. Over time, plants subject to this poor treatment and may need to be replaced. 

To learn more about when to prune, advantageous versus detrimental techniques and more, I encourage you to watch this webinar by Eric Hammond, Director and Horticulturist at Adams County Extension.

Additional Resources

I want to finish with information on pruning hedges, as well as evergreen shrubs, since they need quite different methods than described above. Some helpful information on those topics:

I hope that everyone enjoys their spring gardening season!

Vegetable Gardening for Kids

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

Gardening is a great activity to do with kids, whether they’re in preschool or young adults. In addition to teaching children a new skill set, it introduces them to new foods (they like eating what they grow!) and incorporates great lessons such as protecting the environment, healthy and nutritious eating habits, water conservation, and more. It also teaches children the benefits of helping others in need by donating extra produce to food banks.

Gardening is also a great, hands-on way to teach children the life-cycle of plants. All plants begin as seeds. About five to eight days after planting, the seed will sprout. You will see a green “stem” poke above the soil. Two seed leaves will begin to form, and then larger true leaves will appear above the seed leaves. The plant will flower and the flower will become the vegetable (beans, peas, tomatoes, peppers). Some vegetables (like carrots, onions, and beets) are actually roots. By fall, the plants that have been growing all summer will begin to get brown and die.

If you want to grow a garden this summer, these are some veggies that grow well in our Colorado climate:

  • Edible pea pods
  • Peas
  • Kale
  • Spinach
  • Leaf lettuces
  • Green Beans
  • Zucchini and other squash
  • Cucumbers
  • Peppers
  • Tomatoes
  • Onions/scallions
  • Beets
  • Carrots

What You’ll Need to Garden

A few tools make gardening easier:

  • Shovel – This is essential for in-ground gardens to turn the soil.
  • Trowel – Best tool for digging small holes and trenches.
  • Gardening gloves – Keeps your hands clean. Buy them in children’s sizes for kids.

Decide Which Type of Garden You Need

In-ground or Small Raised Garden Bed

While these gardens are small, they can hold a lot of veggies. Pole beans, cucumbers and squash can be grown in them. Cucumbers grow tall and can be tied to stakes or cages, and lettuce and other short plants can be planted around the base of the taller plants.

Even if you only have a small space to work with, you can easily grow:

  • tomato plants
  • pepper plants
  • carrots
  • pole/green beans
  • peas
  • onions
  • cucumbers
  • zucchini
  • lettuce
  • brussels sprouts

Container Gardens

Containers are a great way to introduce kids to gardening. It’s easier to prepare the soil in pots, they have fewer weeds, and rabbits can’t reach the taller ones.

Get Started

If you’re new to gardening, START SMALL! For the best outcome, plan your plantings on paper first. Get creative with your design – you can plant a LOT of veggies! For in-ground gardens, start by preparing your space. Dig up an area of ground about 4 feet x 4 feet.

A sample garden design could have three mounds of cucumbers, three rows of bush green beans, two rows of beets, and one row of onions.

Root veggies like beets and carrots need to be thinned out once they sprout to allow room for the roots to develop.

Prepare the Soil

If you’re building an in-ground garden, remove all of the grass and weeds from your new area. Mix in good top soil and compost (available at garden centers), and work it into the ground soil.

If you’re using containers, put holes in bottom of the container for drainage, and cover holes with a piece of very thin cloth or coffee filters. Fill clean containers with potting soil (available at Garden Centers). Make sure your garden is located in full sun if you’re planning on growing veggies, as 6 to 8 hours of daily sunshine is needed.

Decide When To Plant

When buying plants and seeds look for maturity dates of 48 to 85 days. Planting during the correct time of year will help make sure your vegetable garden is successful.

Use the following list as a guideline:

  • April: Plant cold weather crops like peas, lettuces, spinach, and kale.  
  • Early May:  Plant carrots, beets, and onions.
  • Mid to late May:  Plant tomatoes, peppers, squash (zucchini), cucumbers, and beans. Hot weather crops can be planted when the soil reaches 60 degrees.
  • June: Continue planting cucumbers and beans so you can harvest veggies continually from July through September.

To get veggies over a longer period of time instead of having one big harvest all at once, plant a row or two and wait a week before you plant more.

How to Plant

Look at your seed packets for instructions on how deep and how far apart to place seeds. Follow those guidelines, but also be aware that you can plant seeds closer together in containers than you do in the ground.

If you’re using starter plants (young plants that have been grown already and just need to be put in the garden), carefully remove them from their pots, put them in the soil at the same height as they were in their original pots. (Tip: Tomatoes can be planted deeper to develop more roots.) Water the ground or container immediately after planting.

Maintain Your Garden

Make sure your garden gets enough water throughout the season. Check daily by putting your finger in the soil; if it feels dry, you need to water! The garden will need more water in the middle of the summer when it gets very hot and/or windy. Containers need daily watering, sometimes twice a day in really hot weather.

Water early morning so plants dry out before going to “bed” at night.  This helps prevent diseases and fungi from spreading. Pull any and all weeds that you see!

Fertilize your in-ground garden by mid-summer and your containers once a month from June through August.

Harvest Your Vegetables

You can check the seed packet to determine the number of days from planting to harvesting, but the plants will usually let you know when they’re ready to harvest. Most tomatoes are ready when they are bright red unless they’re meant to be yellow or other colors. Root veggies will begin to “pop” out of the soil when they are ready to pick. Beans and peas should be harvested when they’re firm and medium size. They get tough when they get too large. Lettuce can be cut at any size, but if you leave half the plant more leaves will grow. By mid-summer lettuce starts to flower and gets bitter, so try to complete your harvest by then. Watch your squash and cucumbers closely! They grow fast and need to be picked before they get large. Similar to lettuce, they’re not so tasty when they get huge.

With plenty of sunshine, water, and a little fertilizer, you will be ready to harvest by mid summer. Have fun and prepare to eat delicious veggies!

If you have specific questions, please call the C.S.U. Denver Extension office at (720) 913-5178.

Colorado Gardening Calendar for April and Grow & Give 2022

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

April is one of my favorite months in Colorado, a time when signs of life are everywhere –– trees are budding, the crocus and daffodils are in bloom. Mostly empty garden beds beckon, promising beauty and bounty for the next six months. And, while the garden to-do list is long, I feel inspired to tackle each task and eager to be back in my garden.

Having a monthly “to-do” gardening list helps break down the many gardening tasks into less overwhelming chunks, reminding me what to do when. April is a great time to get your gardening ducks in a row, peruse your favorite gardening centers, prep your gardening soil for planting, and begin putting a shovel and seeds in the soil. 

A Gardener’s Yard and Garden Checklist for April

If you haven’t done it yet, it’s time to finish cleaning up of last year’s garden, removing any annual plant remnants, cutting back perennials and pulling early emerging weeds. Clear any mulch, such as dried leaves laid last fall over vegetable beds or around perennials. Add compost if you didn’t do it last fall. When the soil is mostly dry and workable, add 1-2″ of compost into your soil at a 3-5″ depth.

Also consider testing your soil. It’s not too late! I wrote a blog post last January about getting your soil tested. Testing is the best way to fully understand what your soil needs to growth healthy plants.

Here are some additional April gardening “to-dos” in Denver: 

Vegetable Garden

  • Plant cool weather seedlings such as broccoli, cabbage and cauliflower. Want to grow asparagus or rhubarb? Now’s the time to get those perennials into the ground. 
  • Direct sow early season veggies and greens, such as arugula, peas (I soak in warm water in advance for quicker germination), spinach and radishes. Water well if rain is sparse. 
  • Plan for snow and hail. How will you try to protect your early plantings? It’s always good to have some old bed sheets or plastic near your garden in case a late winter storm or spring hail passes through. 

Trees and Shrubs

  • Look closely at your trees for any winter damage that may need an arborist’s attention. Inspect shrubs and other perennials for signs of life. Take note of plants that should be showing initial green or growth but are instead brown and brittle. This way, you can inspect again in a few weeks and determine if they need replaced. 
  • Start planting both shrubs and trees if the ground is thawed. Water thoroughly.

Lawn Care 

Perennial Flower Beds 

  • Remove any dead foliage still lingering from last season and pull early-season weeds.
  • Divide perennials that have grown too large for your space or haven’t been divided in a few years. It’s good for the plant and your budget! You can store in pots and water until you’re ready to plant elsewhere in your yard or give them away to neighbors. 
  • Sow some wildflower seeds for flowers pollinators will love later. Water well. 
  • New growth for roses can typically be seen as April progresses. Prune canes that are damaged or dead and then all others (except climbing roses) to 12” to 24” above ground. 

Annual Flower Beds

  • Start planting early-season annuals that can tolerate light frost. Consider pansies earlier in the month and flowers, such as snapdragons and sweet alyssum, later in April. 

(For additional April gardening tips and ideas, check out the CSU Extension garden calendar for April 2017.)

Grow + Give Program

If you’re a Denver vegetable gardener, start thinking now about joining CSU’s Grow + Give, a modern victory garden project. The goal of the Grow and Give program is to help address food insecurity in Colorado.

If you commit to the program now, you can plan to plant a little extra to donate to your neighborhood food pantry, neighbors in need, or other organizations that accept excess produce. Visit for details. Watch for the 2022 season sign up; it should be posted soon. 

Gardening…It’s for the Birds!

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

“By creating a garden for birds 365 days a year, I accidentally created a 365 day garden”, said The New York Times writer and longtime gardener Margaret Roach. That got my attention! A 365-day garden and more bird activity? Yes, please. 

Whether floating through neighborhood yards or migrating cross country, birds seek refuge, water, and nourishment throughout the year. With nature in mind, we can design spaces where birds can thrive safely, relax, raise their young, and become our visitors and backyard companions.

In Denver, Black-capped Chickadees, Chipping and Vesper Sparrows, Dark-eyed Juncos, and House Finches are common, especially in yards with feeders. Other visitors include Robins, Crows, and Northern Flickers which really like scratching for worms and the larvae of bugs and wasps, and Broad-tailed Hummingbirds which love to buzz trumpet-shaped flowers and sugar-water feeders. 

Dr. Stephen W. Kress of The National Audubon Society gave an extensive interview on caring for birds in winter covers LOTS of ground for healthy bird-inhabiting gardens (specifically minutes 5-13).

Food Sources 

Creating a food zone within a garden is key to attracting birds. The yard is the most natural and beneficial bird feeder available to them (and other pollinators) and its all uniquely disguised as flowering and fruiting gorgeousness, shade, sun, and seasonal changes that gardeners also get to enjoy all year long, too!

Bugs are very high on the scale of ‘things’ birds like to eat. When you’ve got delicious bugs, the birds will be there to enjoy them! Beneficial insects are important on many levels, explains CSU Emeritus Professor of Entomology, Whitney Cranshaw.

Please take the time to identify bugs you are inclined to squish, spray, or eliminate. Finding out if the bug we’re giving the hairy eyeball necessitates drastic action or is merely weird looking but harmless is important. Birds return to spaces that contain their preferred delicacies. Insects of choice include grubs, crickets, beetles, aphids, grasshoppers, moths, flies, ants, and worms. 

Plants that hold their fruit, seeds and berries through winter provide birds a vital food source during winter months and reward us with winter interest as well. 

Different seeds are attractive to different birds. A variety of feeders, seed offerings and the placement of both are invitations to visit. Placing feeders either within 3’ of windows OR more than 30’ away from them minimizes bird-window collisions which is a leading cause of songbird deaths.


Water is the easiest and most essential factor for backyard birds. Most birds do not benefit from snow crystals as a water source during winter. The energy required to keep their body temp stable can’t compete with the temperature of the ingested snow.

As birds look for water daily, de-icers in birdbaths and water trays are tremendously helpful during snow days and/or consecutive days of below freezing temps. 

Rocks or bricks next to water sources provide perching and a little solar warmth for them and make those watering venues more attractive. 

Like bird feeders, water trays and birdbaths need regular cleaning to keep birds healthy – wear gloves during this chore for your health, too. 


Seriously Zen advice about bird habitat is to just let things ‘go’ a bit. A decaying tree trunk or small brush pile for cavity nesters, withered and wilted perennials equal nesting material, and a dense thicket or hedge accommodates escape-cover and summer shade.

Edges of gardens where different ‘scapes’ meet (short perennials against a sturdy shrub next to a grapevine or deciduous tree) are very beneficial to insect populations and therefore to birds.

Native plant gardens are wildlife habitats and contribute to biodiversity.

Birds appreciate protection from the wind and weather: grapevines on the trellis all winter, a thorny barberry in the corner, and a robust conifer abound with sheltered respite. Also a good spot for tracking whose turn it is in the birdbath!

Organic, IPM, PHC Gardening

Each year, herbicide use, climate change, and habitat loss are impacting the bird population. Organic gardening lends itself to healthy bird activity as less chemicals simply equal more living things. The more organically you garden, the more delicious bugs you will have to entice birds. Following Integrated Pest Management and Plant Health Care practices help gardeners to plan wisely, thoughtfully maintain landscapes, and address concerns with the best intent for flora and fauna.

Every tree and plant we place, every plant we let go to seed or don’t whisk away during fall cleanup, and every Buggy McBugbug we don’t spray makes a difference to our feathered friends regarding seasonal habitat and year-round food sources.

When bugs and advantageous plants are plentiful, birds are too! Seeing their acrobatics and hearing their songs are highlights of the landscape throughout Colorado’s seasons. 365 days, please!

Further reading

Plant This, Not That. Colorado Native Plant Society.

Colorado Native Shrubs for Landscapes. Colorado State University Extension Fact Sheet 7.422. 

The Audubon Society Guide to Attracting Birds: Creating Natural Habitats for Properties Large and Small. Stephen W. Kress, 2006.

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!

Sunflowers and Ukraine

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

The sunflower (Helianthus spp.) is the national flower of Ukraine. Just like the Ukrainian people, they are strong, resilient, and hold their heads high.

Thoughts are with Ukraine today.

Testing Your Garden Soil for the 2022 Gardening Season

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

For some reason, soil testing always overwhelms me, so I tend to put it off on my spring garden planning “to do” list. Yet, I know that proper pH levels, soluble salts, organic matter, nitrogen, phosphorous, potassium, sulfur, micronutrients, and other soil components are critical to my gardening success. In my vegetable- and flower-focused home garden, I know properly attending to my soil will lead to an abundance of nutrient-dense veggies and healthy cut flowers.

I’m determined this year to understand my soil better and conduct a proper soil test — as early as possible. Results from this test will tell me what nutrients my soil needs, or where the soil is out of balance. It will equip me with the knowledge necessary to apply soil amendments for optimizing my growing conditions, such as compost, worm castings or aged manure, before I begin putting seeds or starts in the ground.

Getting Started

Luckily for us Colorado gardeners, the soil lab at Colorado State University (CSU) makes soil testing a simple process. On their newly revamped website, you can find all details for collecting your soil sample, choosing what information you’d like to glean, pricing for each sample, and where to send the sample you’ve collected. 

The lab was extremely busy in spring 2021, and it’s anticipating significant volume again this spring. That said, it’s recommended you collect and submit your soil samples as soon as possible — as early as your soil can be worked this spring. 

Keep in mind that your soil test results will only be as reliable as the quality of the sample you submit. Your sample must reflect the average fertility of an area, field, garden, or flower bed, so it’s important to follow the sample collection directions provided here

Prices for sampling range from $10 to $140, depending upon what’s being tested. Multiple tests can be ordered for the same sample. 

Collection Process

The process for collecting a sample is outlined in detail on the CSU Soil, Water and Plant Testing Laboratory website. I’d recommend you head to their site, print the key information, and take it into your garden to guide your sample collection. You’ll then have all information needed at your fingertips as you are going through the process. Following are a few required key steps.

First, be sure you have all essential sampling tools gathered. These include:

  • Stainless steel soil-sampling probe, an auger, or a shovel/trowel
  • Clean bucket
  • Plastic bags or waterproof, lined paper bags
  • Permanent marker

Next, refer to the “Sample Collection” section on the website (or the information you’ve printed to take with you for your sampling) and follow the recommended patterns to gather your representative composite sample. This is the part that always feels a bit challenging to me, but the images provided on CSU’s sampling website really does make it simple to follow. 

Once you’ve collected the samples as directed on the site, follow directions for preparing your sample for shipping, including filling out the sample form. 

When your test is complete, you’ll receive results and an invoice. Payment is due at that time. 

Ingredients for Success

Understanding your soil and giving it more or less of what it needs to grow healthy plants, should be starting point for every gardener. Soil testing and amending will help give your seeds, perennials and starts a great beginning — just add water, sunshine and some regular weeding and pruning. These are all the ingredients necessary for an incredible garden that teems with life, health, and abundance! 

Colorado Gardening Calendar for February

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

February is one of the best months for planning for spring (aka daydreaming about blooming plants and wonderful veggie gardens!), looking after your indoor plants, and continuing to take care of your outdoor plants and lawn during low water periods. Mark your calendar to get these gardening to-do’s done in your yard and garden.

Vegetable/Flower Garden

Begin planning which seeds you are going to start in spring. It’s hard not to get over-excited and overwhelmed (I am just writing this blog) by all the seed choices so try to be strong! Here are some great articles about that process: 

Trees and Shrubs

Lawn Care 

  • This is the period to perform lawn clean-up such as a light raking to remove stray leaves, twigs, dead growth, and winter debris. This allows sunlight and air into the soil to encourage growth.
  • As before, if there’s a lack of precipitation, consider watering when the temperatures are above 40 degrees with no snow cover, at mid-day to allow water to soak into the lawn.

Perennial/Annual Flower Beds 

  • Think about what plants you might add to your flower beds. To get you in the mood for choosing new plants, take a look at the CSU Flower Trials site. It’s kind of like a Hunger Games for flowering plants (just kidding), where they follow the progress of specific cultivars over a three-year period to see which have proven to be most adaptable for the Front Range of Colorado. 
  • Late February is an ok time to plant cold-hardy annuals such as pansies, if the weather is nice enough.
  • You might be tempted to start working the soil in preparation for planting but wait! It’s still too cold for the soil (and you honestly), as it will cause damage to the soil structure this early. 

Indoor Plants

  • Let’s not forget the wonderful indoor houseplants we might have, and continue to tend them but remember, be careful not to overwater. Don’t just water on a schedule. Check the need for water based on feeling in the soil down to at least the first knuckle (about 2” down into the soil in more than one location) or use a moisture meter. Sometimes being a good plant parent means tough love.
  • This is also a good time to wipe them down to clean off dust and help their leaves to breathe.
  • Just as people tend to “slow down” in winter (think “too cold to go out so I’ll sit on the couch and become a potato”), so many of our plants also slow in their growth. Winter is a period of dormancy for many of them. In the main, try to refrain from fertilizing at this time as it will upset their natural cycles of growth and dormancy.

Of course, you can always visit the CSU Extension Yard and Garden website for more gardening tips.