Colorado Gardening Calendar for March 2024

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

Snowdrops popping up through the snow (photo by Pixabay)

Hey friends, remember when it was January, and we were all lamenting how it seemed to never end? And then February was unseasonably warm and short, but Punxsutawney Phil did tell us early spring!  Well, celebrations are in order because it’s MARCH!

This is one of the best months for watching new growth come up and reigniting that gardening bug. Of course, there are other, more “productive” tasks to perform as well, so mark your calendar to get these gardening to-do’s done in your yard and garden.

Vegetable Garden

Coming soon to a veggie garden near you! (photo by Pixabay)

So, my first attempt at veggie gardening was “fun,” but because I’m not super into cooking it may have stopped me from being more attentive to my sad plants. That’s ok, maybe I’ll stick to flowers instead. For those of you who are more dedicated than I, take a look at some tasks below and know that gardening in Colorado usually requires the fastest-growing, most weather-hardy vegetable varieties.

• Clean out debris and replenish soil in vegetable beds while we wait for our seeds to start.
• Starting seeds indoors in March is perfect for any vegetables that should be planted outdoors in early April. Here is a list of seed companies if you are thinking of starting your vegetables from scratch.
• This link from The Old Farmer’s Almanac has all the recommended indoor and outdoor planting dates for vegetables and herbs.
• Think about layouts for your raised beds (if that’s what you’re using). This pdf has a lot of helpful information.
• Since spring seems to be coming early, vegetable garden water conservation might be a good topic to study.

Trees and Shrubs

Early spring Forsythia bloom (photo by Pixabay)

• Late winter/early spring are ideal times to trim trees, as explained on this page by the Colorado Forest Service.
• Precipitation in late 2023 was sparse, so it’s always a good idea to remember good watering habits for our trees and shrubs.
• This interesting article explains tree root systems and how our soil health, moisture and compaction (or not) can affect these very important plants.

Lawn Care

To lawn or not to lawn is becoming a much-discussed subject, given higher temperatures and lower precipitation amounts. Historically, many homes have yards planted with Kentucky Blue Grass lawns, which need more water, mowing and fertilization. This might be a good time to consider replacing your lawn with more native grasses (if you want to keep a lawn) or other native plants.

• In conjunction with Denver and other counties’ water providers, Resource Central has a lawn removal program to assist with moving to more natives.
• This is a great article about what native lawns can be planted instead of that water-hungry bluegrass.
• For those who want to keep their lawns as is (no judgement here!), mid- to late-March is a great time for aerating and general tidying.

Perennial Flower Beds

When I first became interested in gardening, I was – like all of us, I’m sure ­– in love with plants that were different looking, showy, flowering and easy to grow in places like Alabama, but not Colorado. I’m finally learning my lesson that it really is about the principle of right plant, right place. In addition, having listened to and read books and articles about the benefits of planting natives in our landscapes, I am becoming more attentive to what plants I choose for my landscape. I look not only for beauty, but regeneration and restoration. I mean who wouldn’t want to be part of a national movement like Homegrown National Park?

• Since I’m on my native plant kick, here’s a plug for these Colorado native perennials that can really enhance our landscapes and make them more sustainable.
• This is also a great month to start clearing out old, dead growth – as long as the weather is warm enough – to make room for shoots popping out of the ground.
• This page gives great information on perennial gardening so you can have everything prepped when you’re ready to put actual plants in the ground.

Annual Flower Beds

• Even though you can plant annuals pretty much anytime, they MOSTLY like being planted after last frost (usually around May 10-15).
• This is a great time to look at cool-weather annuals like pansies.
• The annual CSU Flower Trials have tested and found flowers that are hardiest and grow best through the tough, Colorado life. Check it out!

Make sure to mark your calendar for the May Denver Master Gardener plant sale (May 18 & 19) and visit the CSU Extension Yard and Garden website (https://extension.colostate.edu/topic-areas/yard-garden) for more gardening tips.

Colorado Gardening Calendar for November 2023

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

If you haven’t already, it’s time to clean out your garden beds. Photo: Molly Gaines

Right on time, we’ve had our first freeze and snow here in Denver. Yet my garden still sits, hanging on for dear life, in desperate need of clearing, composting, amending and mulching. I guess I’ve been in denial, holding on to my fading zinnias and still-green tomatoes, enjoying this gorgeous fall with its warm temperatures and prolonged tree color. Luckily, November is still likely to bring a few mild days. So now’s the time to make a list and check the boxes before everything goes into hibernation until next spring.

A Gardener’s Yard and Garden Checklist for November 

Vegetable Garden

• Clear all plantings and compost. Pests and diseases can overwinter in plant debris and wreak havoc on next year’s garden (aphids, anyone?). 
• Oh my do I have a lot of green tomatoes, around 40 at last count. If you’ve been covering plants to extend the season, it’s time for your final harvest. For ideas on storing late-season produce, visit this helpful page from the University of Minnesota’s Extension office. For a fun recipe from Martha Stewart on cooking green tomatoes, visit here.  
• Spread and work compost into your garden beds before the ground freezes. 

Harvest any remaining vegetables that were lucky to survive the initial frosts. Photo: Molly Gaines

Trees and Shrubs

• Remove dead tree branches, including those on shrubs and roses. 
• Water new fall plantings weekly, including trees, and other perennials until the ground freezes. It’s important to water throughout the winter during warm, dry periods to support healthy roots and next year’s growth. 
• Wrap the trunks of young trees to prevent sunscald, which can occur during periods of alternate warming and freezing in the winter. “On at Thanksgiving, off on tax day” is a good rule of thumb for utilizing tree wrap.
• Protect evergreens with burlap plant bags to prevent them from drying out. 

Lawn Care 

• Fertilize a final time; in Denver this can be done up until Thanksgiving. For more information about fall lawn fertilization from PlantTalk Colorado, visit here. 
• It’s time to blow out and shut off irrigation if you haven’t already. Rake up leaves and either compost or mow over them for garden bed mulch.

Perennial Beds 

• If you haven’t cut back grasses and flowering perennials for the year, let them be. Dead plant stems and leaves provide habitat for moths, beneficial garden insects and butterflies that overwinter.
• Continue watering until the ground freezes. This is especially important for all new plantings. 
• As long as the soil is workable, plant bulbs for spring flowers in the next few weeks. They should still have time to establish before the ground freezes. Water in well. 
• Dig up and save dahlia tubers. Allow them to harden off for two weeks after frost before storing. Find directions here.

Other Projects 

• Bring indoors any houseplants or other potted plants you’d like to save. Hopefully, they’ve survived under heavy protection so far.
• Sanitize, sharpen, and oil tools, including the lawnmower blade. Come spring, you’ll be grateful these tools are ready to go. 

Hope it’s not too late to get houseplants indoors! Photo: Molly Gaines

Follow Up: Denver’s Tree Canopy Survey 

The City of Denver published the results of the September survey of residents about Denver’s tree canopy — and the future of our urban forest. Overall, support for private tree protection is strong. A few points to note from the survey summary: 

• More than 85% of all respondents support private tree protection for trees over 18 inches in diameter. 
• There are differences between renters (17.49% or 378 responses) and owners (75.8% or 1,638 responses) with renters more supportive of the city taking over tree maintenance and for minimum shade requirements. 
• There is overall support for a fee to help maintain street trees, which is highest at the $50-75k income bracket (75%) and is lower for the highest and lowest income brackets ($150k+ at 67.05% support and <$25k at 66.67% support).

Remember to visit the CSU Extension Yard and Garden website for more gardening tips and to prepare for next year’s season. You can also reach out to the Colorado Master Gardener’s office with any yard or gardening questions: 720.913.5270 – we’re available year-round!

Colorado Gardening Calendar for May 2023

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

May is finally here (or What? Already? Depending on your point of view). Now we can get down to the real business of planting. While Denver’s last frost generally falls between May 5^th and 15^th, we know the weather can change at any minute (remember last year’s snow on the 21^st?), we can make progress on many gardening tasks to keep us happy.

First, mark your calendar to make sure you don’t miss the Denver Master Gardener Plant Sale on May 20^th and 21^st at Harvard Gulch Park. We think it’s the best plant sale around!

Next, look at the information below to make sure you have garden success this month.

Vegetable and Herb Garden

This is something I’m attempting more of this year and am excited that the time has come to begin. Having said that, I KNOW it’s important to pay attention to temperatures, light and water needs of veggies and herbs so will be reading up as much as possible to have success. Wish me luck!

Here’s some solid advice.

• Now is the time to plant colder weather veggies and herbs. These include lettuces, spinach, peas, broccoli, cabbage, among others. This article gives great information on cool season veggies.
• Wait till later in the month, when the soil has warmed up and evening temperatures are consistently above 50 degrees, to plant warm season veggies such as tomatoes. Same for everyone’s favorite herb, basil. Learn more here.
• Before planting in the garden, be sure to harden off, or acclimate transplants to outdoor temperatures to help them establish. Find tips here.
• If you are wanting to plant herbs look at this AWESOME pdf with so much information.
• This page gives information on every veggie and herb related subject you could want! Beware of analysis paralysis (my “toxic trait”) as you slide down the rabbit hole of content.

Crabtree blossoms by Miranda Podmore

Trees and Shrubs

• With all the wonderful moisture we had earlier this winter, it’s tempting to think that Mother Nature will take care of our trees, but this is the time to watch and if necessary, water deeply once per week.
• Look at pruning shrubs and trees to maintain their shape and remove any winter kill. Prune early season bloomers such as forsythia and lilac shortly after blooming as they flower on last season’s growth. Use this guide to help you.
• Last week’s post about five trees to consider planting contains useful information on selections you might add to your landscape this month.
• Probably everything you ever wanted to know about trees and shrubs is right here!

Lawn Care

• I thought I’d seen all there was to know about lawns (well not really, but still…there’s a lot of information out there on the world wide web!), but here’s a great all-in-one information source for selection, care, replacement and general best practices for Colorado lawns.
• Perhaps waiting a bit to mow will allow pollinators who utilize the flowering plants in our lawns (dandelion, clover) to have just a bit more food.
• Consider converting your turf to more water-wise options. It’s a worthwhile proposition.  Here’s a great guide to help get started.

Perennial Flower Beds

• Get ready as the time to plant your perennials is nigh! The old adage of waiting until Mother’s Day may or may not be quite accurate but this month is definitely the time when we can fill in spaces in our landscape with plants which will return again and again.
• This is a great guide on how to prepare the planting site and how best to plant for success.
• If you are looking to attract more pollinators, this is an excellent guide to selecting plants.

Annual Flower Beds

• Annuals can provide so much needed color after a drab, cold winter and there are many which are cold hardy that can go in the ground early this month. Take a look at this information sheet.
• CSU conducts flower trials every year which showcase the best performers over a three-year period. Use it to make your choices for both annual and perennial plants.

May is certainly a great month to catch the gardening bug (no pun intended), get back to enjoying the warm weather, and get our hands in the soil!

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

Colorado Gardening Calendar for April 2023

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

A reminder to resist the urge to plant frost-sensitive flowers and veggies this month. Ice encapsulates this blooming tree in mid-April.

As the saying goes, “April showers bring May flowers.” But in Denver, where one day the snow flies and the next day is sunny and 70, April is mostly a planning and prep month here. It’s a hopeful and exciting month for gardeners, filled with possibilities and dreams that this year, “I’m finally going to [fill in the blank] in my garden.” For me, it’s that I’ll finally install drip irrigation vs. hand-watering my vegetables and flowers. For you, it may be planting trees for some much-needed shade or creating your first vegetable garden. Whatever your goals, following is a guide to help keep your April gardening tasks on track.

Vegetable Garden

• Clear debris from last year’s garden and any winter mulch covering the bed, such as dead leaves. Pull any emerging weeds, which are easier to deal with early in the season.
• When the soil is dry, not wet, or muddy, add a fresh 2-3-inch layer of compost to your beds. This will greatly support soil health and the vigor of your plantings. Gently work compost into the top layer of your existing soil with your hands, a trowel or a cultivator. Let rest a few weeks before any planting begins.
• Plant frost-tolerant spring plantings, such as peas, spinach, arugula, radishes, Swiss chard, etc. You may wish to soak your pea seeds in warm water prior to planting for faster germination. 
• If you haven’t yet started indoor seeds for warm-weather vegetables such as tomatoes, peppers, squash, melons, etc., now is the time. 
• Reference this Vegetable Planting Guide to plan for what you will plant when. 

Trees and Shrubs

• Continue hand-watering your trees and shrubs, particularly if it is a dry April.
• Early this month, prune deciduous trees and shrubs. 
• Remove broken branches from trees. Clear away dead leaves and decayed fruit from the base, as they can house unwanted inspects and pathogens. 
• I’ve sadly been noticing a lot of tree removal in my neighborhood lately. Denver needs a more robust, healthy tree canopy. This is a great month for planting new trees, selecting varieties that best suit Denver’s climate. Here is a guide to successful tree planting. If you’re in the market for a tree, check out the Park People’s annual tree sale on April 22, which supports the Denver Digs Trees program.

Lawn Care

• Prep your mower, sharpening the blade as necessary and conducting any other necessary maintenance. 
• If you use a pre-emergent weed product, apply before weed seedlings – particularly crabgrass – sprout. Targeted weeds can vary by product.
• Fertilize as desired, reading labels for proper application.
• Denver Water recommends waiting to turn on your irrigation until after the last freeze, typically in early May.

Perennial Beds

• Cut back perennial plants if this wasn’t done last fall, leaving 3 inches of the plant above the soil.
• Plant asparagus, rhubarb, berries, bare-root roses. Soak any bare-rooted plantings for a few hours prior to planting.
• Pull emerging weeds now, staying on top of them early in the season.
• Divide perennials that are overgrown, such as chives, sedum, grasses, phlox, daisies, hosta, etc. This will lead to healthier plants and better growth. It will also allow you to give away new, inexpensive perennial plantings to your neighbors and friends. 

Other Thoughts for April Gardening

• Inventory and prep garden supplies. Sterilize and sharpen garden tools. 
• Sow wildflower and pollinator seed mixes.
• Consider and plan for any trellising that may eventually be needed for your vegetable and perennial gardens.
• Be prepared for frosts and bad weather. Have sheets of plastic and old bedsheets nearby your garden for quick tarping in case of late-season snow or hail.

I hope this list makes tracking all of the April garden to-do’s a bit simpler. And remember this about April: attentiveness and proper planning for your landscape and gardens now means less work and hassle, and more ease and enjoyment, as your summer gardening season progresses.

Organizing and assessing  tools and supplies needed for the gardening season.

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