Colorado Gardening Calendar for May 2024

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

This is the month we’ve been waiting for! May is the best month for getting your plants from the Master Gardener Plant Sale on the 18^th and 19^th and planting them, with the caveat that anything can happen weather-wise, so be ready…remember 2 years ago?

Vegetable Garden

• This is the time to direct sow hardy, cool season vegetable seeds such as lettuce, kale, and spinach.
• Plant your (newly purchased!) veggies and herb plants when nighttime temperatures are consistently a minimum of 50 degrees, and make sure to protect them with cover when temps drop below 40 degrees. This includes tomatoes, peppers, and eggplants.
• Consider your planting location, i.e. Rotating your crops to prevent bacteria that might have infected plants last year from doing so again.
• Weeding is essential as much as possible, so let’s get on it!

Trees and Shrubs

• Just in case May ends up being sparse in the precipitation arena, don’t be afraid to bust out your hose and give your trees a good soaking, watering deeply once per week.
• This is also a good month to prune trees to remove any dead branches from needed but possibly damaging snowfall.
• Mulching is a great way of helping your tree retain water, just make sure to keep it between 3-4” deep and about 6” away from the trunks so it doesn’t hinder healthy root development and allows the plant to take up moisture.
• Prune summer blooming shrubs that bloom on new growth, such as roses before they begin to flower. Refrain from trimming shrubs that bloom on old growth such as lilacs until after they flower.
• This information sheet has great pruning information.

Lawn Care

• This is a great month to aerate the lawn to loosen up soil for better water absorption, as well as removing thatch (tight, brown, spongy, organic layer which can cause problems down the road in terms of lawn health) when it becomes too thick.
• After aerating is a wonderful time to overseed your lawn to regrow any bare spots which have developed over time.
• Watering is important for lawns as for other plants as this month heats up. Of course, if there’s rain or snow, hold off.
• Watering in the late evening or early morning helps retain more water as the weather tends to be cooler and more humid at these times.
• This is the month to treat your lawn for Japanese Beetle grubs. Use products like GrubGONE! which has been shown to do a great job of stopping this pest before it leaves your lawn and infests your plants.   

Perennial / Annual Flower Beds

• Continue cleaning out the garden, including spent flowers and cutting back foliage to help perennial plants direct their energy to growing.
• Look at possible locations where plants might not have performed as well as desired and where you can fill in or move existing plants.
• Waiting until late May to plant annuals will give them a chance to survive any crazy cold spells, although there are many that will do well in cool weather, such as petunias and pansies.
• This is also a great time to plant summer blooming bulbs!

May is such a great gardening month, let’s take advantage it and grow, grow, grow!

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

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.

Growing Garlic in Colorado

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

Photo credit: Felicia Brower

*There’s still time to get your garlic in the ground! This week’s blog post is an older post with updated photos, and it covers what you need to do now to have great garlic next year.*

As we wrap up our gardens this season, we can begin to think about all of the crops we want next year. If garlic is on your list, now is the time to act.

Garlic (Allium sativum) is easy to grow and a great crop for beginner gardeners. Even though you’ll harvest in July, you’ll need to plant before the end of October. When choosing which garlic you want to plant, know that you’ll need to purchase your bulbs from a garden center, a farmers market, a garlic farm, or a seed catalog (now is the time to place orders for garlic — they sell out quickly this time of year). Grocery store garlic is often treated with anti-growth products that will prevent you from being able to grow your own bulbs from those cloves.

If it’s your first time purchasing seed garlic, you might be surprised at all of the varieties that are available. Each variety has a distinct flavor and an average number of cloves to expect per bulb, so do your research, and choose accordingly.

Choosing Garlic Varieties

There are two distinct types of garlic to choose from: hardneck (ophioscorodon) and softneck (sativum).

Hardneck

Hardneck varieties are easy to identify because of the (you guessed it) hard neck or stem that you’ll find in the center of the bulb. While hardnecks don’t store as long as softnecks, the flavors are often described as being more intense. Hardneck garlic plants produce a scape, which looks like a curly spike with a small bulbous end. Scapes tend to show up a month or so before the plant is ready to harvest and need to be removed so that the plant can continue to send energy down to the development of the new bulb. Good news: scapes are also edible. Popular varieties of hardneck garlic include Chesnok Red, Music, and German Extra Hardy.

A scape on a hardneck variety of garlic. Photo credit: Felicia Brower

Softneck

Softneck varieties are often chosen because they tend to store longer than hardneck varieties, but they have a milder flavor. Most grocery stores carry softneck garlic, and the cloves tend to be smaller and more plentiful. Garlic braids are made with softneck varieties. Popular softneck varieties include Inchelium Red, Silverskin, and Lorz Italian.

Planting Garlic

Garlic plants don’t take up a lot of space and are known to repel rabbits and deer, so consider planting them around the edges of your vegetable and flower beds. Find a sunny spot and prepare your soil by digging a trench. If you notice you have heavy clay soil or very sandy soil, you should amend the soil with some compost prior to planting.

To prepare the garlic for planting, break apart each bulb into cloves, keeping the wrapper on each clove. Choose only the largest cloves to plant to ensure the best and biggest bulbs next summer, and use the smaller cloves for food. Plant the cloves immediately after breaking them apart from the bulb to reduce to risk of disease and excess drying.

Make a trench in the soil three times as deep as the clove. Plant each clove pointy side up four to six inches apart. Cover the cloves with soil, water well, and cover the trench with mulch, leaf litter, or grass clippings. Garlic needs water to grow and thrive, so make sure that you continue to water occasionally (about once every three weeks) throughout the winter season.

The tops of the the plants will start to come up through the winter, but don’t worry. Garlic is a hardy plant, and it should survive. Pull any weeds near the plant as it grows, as they will impact the size of the bulb.

If you plant different varieties in your garden, label each one so that you can make keep records of what grew best and which flavors you preferred for the next time you plant.

While garlic is an easy crop to grow, it is vulnerable to several types of rot. Avoid disease by planting only healthy cloves and being careful not to damage any bulbs while planting things nearby in the spring.

Harvesting Garlic

It’s time to harvest your garlic when the green tops turn brown and begin die down, which typically happens in July if you plant in October. If the soil is loose, you can pull the new bulb up by hand, but if it’s not, use a hand tool to get it out of the soil being very careful not to puncture any of the cloves. If you pull the bulb out of compacted soil, it can create wounds in the bulbs or the stem, which can quickly lead to fungal infections. When they’re removed from the soil, gently brush or rub the dirt off and let the remaining residue dry while the garlic cures. Fresh bulbs are very sensitive and bruise easily, so take care with the removal process.

Curing Garlic

If you want your garlic harvest to last, you need to cure it before you store it. After you pull the bulbs, spread them over or hang them in a warm, airy spot out of direct sun. Do not cover the bulbs with any heavy material, as that can prevent the air flow and encourage rot. If needed, use a lightweight cotton sheet. Store the bulbs at 40-60° F and cure for two to three weeks.

Cured and cleaned Romanian Red garlic. Photo credit: Felicia Brower

For a visual demonstration of how to plant garlic, watch How to Grow Garlic in Colorado – Produced by Tagawa Gardens, a partner in PlantTalk Colorado.

Colorado Gardening Calendar for October 2023

By Margerie Hicks, CSU Extension – Denver Master Gardener since 2010

October is my favorite month to enjoy the vibrant, intense colors and crisp autumn breezes of Colorado. Gardeners need to adjust their routines to ensure a healthy, beautiful garden next year by completing the maintenance tasks outlined here that apply to your garden.

Vegetable Garden

Harvesting carrots and beets photo by a-lesa on iStock

• Harvest and Preserve: Your vegetable garden may still be yielding some late-season treasures. Harvest your remaining root vegetables and squash. Store them in a cool dry place for use throughout the winter. Consider canning or freezing surplus produce or donating some to a food bank. For canning information click here. The first frost will probably occur mid-month, so don’t be caught harvesting one night in a freezing drizzle (I’m speaking from experience); observe the weather reports each day.
• Clean and Compost: Remove spent plants and weeds from your garden beds to prevent diseases and pests from overwintering. Compost healthy plant material to create nutrient-rich soil for next spring. Learn more about composting techniques here.
• Plant Cover Crops: Protect your garden’s soil during the harsh winter months by sowing cover crops like winter rye. These cover crops help prevent soil erosion, suppress weeds, and improve soil structure. When spring arrives, you can simply turn them under to add organic matter to your soil.

Trees and Shrubs

• Blow out the sprinkler system: When water freezes the pipes may crack.
• Wrap the trunks of trees that have been planted in the last one or two years:  Click here for details.
• Prune and trim: See this Colorado State Forest Service pruning guide. Do not prune spring flowering shrubs or you will be removing next year’s blooms. In the future, prune these soon after the blooms fade. 
• Irrigate: Continue to water, and plan for monthly watering all winter on days the temperature is above 40 degrees Fahrenheit.

Lawn Care

child playing in leaves photo by Scott Webb on Unsplash.com

• Rake leaves:  First form big piles so the children in your life can play in them. Then compost the leaves at home or take them, ideally in paper bags, to one of the leaf drop sites provided by the City of Denver. Click here for locations, dates, and times.
• Fertilize: Click here for details on proper lawn fertilization.
• Aerate: Unless your lawn has been aerated since spring, see the sub section of this fact sheet called “Core Cultivation or Aerating” to learn more.

Perennial Flower Beds

Planting tulip bulbs photo by LianeM on iStock

• Plant spring bulbs: Tulip, hyacinth, crocus, daffodil and other spring blooming bulbs can be planted when the weather gets cool. See this fact sheet for important considerations in selecting and planting bulbs.
• Divide and transplant: October is the ideal time to divide overgrown perennials. This process rejuvenates the plants and can also provide you with new additions to your garden. Transplant them to new areas or share them with fellow gardeners.
• Cut back and clean: Trim back faded perennial foliage and remove debris from your flower beds. Consider leaving some plants uncut, such as ornamental grasses and dried echinacea blossoms, as winter habitat and seeds for birds. These and other plants, such as Autumn Joy sedum, provide winter interest to the garden.

Annual Flower Beds

Ornamental Cabbage photo by Santi WiWatchaikul on iStock

• Plant cool season annuals: Extend the beauty of your garden by introducing cool season annuals like pansies, violas, and ornamental kale or cabbage. These hardy plants can withstand the cooler temperatures of late fall and early winter, adding vibrant color to your landscape.
• Enjoy blooms inside: Before the frost, cut any remaining blooms, such as roses, bring them in the house, and put in vases to enjoy the last summer color.

Other Tasks

• Bring in house plants from the patio before the inevitable frost. First, hose off the summer dust and any insects, then let them dry while still outside.
• Wash and store pots; clean, sharpen, and oil garden tools; store for the winter.

October is a transitional month in Colorado gardening. Use this month to prepare your garden for the winter months ahead. Remember to adapt these guidelines to your specific microclimate and garden conditions, and always consult research-based resources such as https://extension.colostate.edu/topic-areas/yard-garden/ for the most accurate advice. Happy gardening.

Colorado Gardening Calendar for September 2023

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

Winecups reaching for water. Photo by Valerie Podmore

When I went on my (mostly) daily morning walk (I’m writing this in the 3^rd week of August by the way), the temperature was a lovely mid 70’s and my walking buddy said, “this is a really nice morning, almost like fall.” As we’ve had so many hot, hot July and August days, the thought of experiencing cooler ones is quite appealing! I’m sure our plants will enjoy that as well (not the walking part of course haha). Let’s look at our gardening to-dos for this month.

Vegetable Garden

Ok I admit, my first attempts at veggie gardening are not going great, mostly because I’ve not watered properly, I think. It could also be the location has much more shade than initially imagined. Remember that right plant, right place mantra? I didn’t! In any case, here are some tasks to perform this month for those of you who actually have real vegetables growing.

• Continue to harvest any ripe summer vegetables and clear out fallen leaves, weeds and other disease-causing debris.
• Plant cool weather vegetables now as they mature quickly and love less heat. These include lettuce, kale, arugula, Swiss chard, and spinach. Here’s a timely post on how to extend our growing season.
• Don’t forget to continue watering because we all know that Colorado can throw crazy weather at us…and it follows then to prepare for cold weather snaps too. There’s nothing worse than working so hard to grow something only to have it destroyed by Mother Nature. 

Trees and Shrubs

• Oh that watering thing again. It’s like some sort of Tamagotchi game (showing my age!) to make us desperately try to keep our plants alive! Keep an eye on the weather and water deeply when precipitation has been scarce. This information sheet has EVERYTHING you want to know about water.
• While we can prune, if necessary, try to avoid it during this month. Make note of branches that need attention and save the tasks for late winter or early spring.
• We may not realize it, but September’s cooler temperatures make it a good time to plant trees and shrubs as it gives enough time for the plant to acclimate in the warmer soil and prepare for the winter months. Here’s a great article on this very idea.

Lawn Care 

• This is a great month to revive our lawns by aerating and fertilizing or overseeding bare spots.
• As mentioned above, watering is still important to keep our lawns healthy so let’s continue caring for our lawns as fall is not the time to stop the good lawn care practices we’ve undertaken throughout the year.
• Tired of dealing with lawn? Now’s the time to start to plan a turf conversion. This page offers practical tips.

‘Autumn Joy’ sedum’s dusty pink blooms pop in September and last till frost. Photo by Linda McDonnell

Perennial Flower Beds 

• This is a perfect time to start cleaning up our plants as they begin to go dormant, by clearing away dead and mushy leaves, fruits or weeds which can cause disease.
• This quick read has good advice on clearing up the garden in the fall and pollinator-friendly clean up tips can be found here.
• Divide early blooming perennials such as iris, lily, hostas, bleeding hearts, and other bulb or tuberous species to keep them from crowding each other too much.
• For anyone who has a spare hour and some, and REALLY wants to nerd out on fall plant advice, take a look at this awesome video!

Annual Flower Beds

Because I’m lazy, I prefer perennial plants but of course we can’t minimize the impact that annuals have in the garden. The colors and variety are just so great!

• Make note of those annuals that you will want to replace next year.
• Get your pots of Chrysanthemums or pansies busted out to provide fall color, as these plants prefer cooler weather and add that color we sometimes need to combat that seasonal affective disorder that we have (well I’m speaking for myself here!).

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

Rinse and Repeat: Extend the Vegetable Season with Canny August Planting

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

Cultivating a vegetable garden this spring was certainly a challenge – we had late snow, followed by almost constant rain and, finally, some killer hailstorms. Seeds and seedlings were drowned or drifted into neighboring patches of soil and planting was delayed due to soggy soil conditions. Then cool temperatures and heavy rains required us to protect heat-lovers like tomatoes and peppers and stunted their growth. 

Late June hail decimated some Denver gardens. Photo: Molly Gaines

As I write this, we’re experiencing some typical July heat while forecasters are predicting a temperature dip that will lower temperatures to a more comfortable level. We can look forward to an abundant second harvest in September and October if we take advantage of better planting conditions this month.

WHEN AND WHAT SHOULD I PLANT?

Before answering the questions of when and what to plant, determine this year’s anticipated first frost date. Do this by counting backward from the number of days or weeks to maturity for each plant species. This will give you the date on which seeds must be planted. 

Find the first 2023 frost date for your city on the website of the Old Farmer’s Almanac. This resource estimates Denver’s first frost to occur on or about October 6^th , however this is only an approximation – keep up with local weather predictions as summer turns into fall. And remember that we can be flexible, thanks to plant protectors and moveable containers! 

Next, decide what to plant. The Denver Urban Gardens site features a guide to vegetable planting for commonly grown vegetables. It shows the recommended number of weeks (not days) to plant before the first frost. The column headed “fall planting” has the information to reference for the late gardening season. Note that we’re inside of or past the optimal seeding date for a number of these plants. Given this, consider using vegetable starts instead of seeds, and/or grow in containers that are easy to move or cover as the first frost approaches.

If seeing drop-dead dates for planting better suits your style, check out the ‘Colorado Vegetable Planting Calendar’ on the Asia Farming website.

Plant radishes now for a fall crop.

Before heading to the nursery –- and certainly before starting to plant –- take a look at Pueblo County Extension’s publication, “Late Summer and Fall Vegetable Garden Planting” for advice on plant selection and improving the tilth of soil that’s been used to grow the summer crop. 

If you like perennial herbs – decorative or culinary –- look for them in pots when you’re out and about looking for vegetable starts and seeds. Herbs like winter savory, lavender, and thyme will overwinter and, in some cases, remain green for cold-weather interest. Mulch well and water regularly until the soil freezes in late November to promote good root growth for a fast start in the spring. Perennial herbs in small containers  can be brought inside during the winter and returned outdoors to perk up the garden as soon as nighttime temperatures warm to a safe level in spring. This website lists some perennials that survive Zone 4 and 5 winters and popular annual herbs for fall planting.

It’s not quite time to plant garlic, but if it’s on your fall schedule, the sheer number of available cultivars and flavors requires researching possibilities and ordering bulbs NOW. Here’s a good article about growing this crop in Colorado, featuring some well-performing varieties. Local nurseries are or will soon be stocking garlic bulbs but consult some mail-order sources for the more exotic types. And for everything essential to know about growing garlic in our climate, check out the Master Gardeners’ September 2020 blog post “‘Growing Garlic in Colorado.”’

PLANNING FOR DISASTER

Inevitably an unexpected run of bad weather will occur in September or October: a hard freeze, rains that drown seeds and seedlings, even a heavy wet snow that brings the growing season to a screeching halt by snapping plant stems in two and withering tender foliage. We can minimize this damage by using a few effective tools:

• Row covers and frost blankets (sheets from the linen closet will work in a pinch)
• Anti-freeze bags (these come in many different sizes and are great for bushy plants)
• Cold frames (require advance construction but are handy year-round)
• Morning watering when frost is expected that night (hydrated plants are more resistant to frost damage)

Good luck with your late-season veggies! As always, please contact the Denver County Extension with your gardening questions. 

Colorado Gardening Calendar for July 2023

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

Roses in bloom for a “hot” minute, photo by Valerie Podmore

With all the precipitation we’ve had this year, our gardens have been busting out all over with beautiful blooms, vegetables are loving it and of course weeds are growing like gangbusters. I bet many of us have not really had to water much yet…how great is that?!

This month let’s get out there and keep on top of the bounty that this amazing weather has brought us, knowing that in Colorado the weather can turn on a dime, so we need to be prepared for anything.

Vegetable Garden

• This is the month when we can start harvesting our ripening vegetables, fruits, and herbs.
• Look to plant vegetables for fall harvest. This information sheet has great ideas!
• Since July is typically hot and dry, we may need to water but make sure not to water from above to prevent mildew and other maladies from forming.
• This article is a great overall guide on caring for veggie gardens. I’ve bookmarked it for my future reference as a beginner veg gardener!

Trees and Shrubs

• While we’ve had ample water this year, we still need to watch the weather and make sure our trees and shrubs are adequately watered when we’ve received no precipitation in 10-14 days to prevent disease. Denver Water has a nice, succinct guide to help.
• Emerald Ash Borer has been detected in a small area of Littleton and Carbondale (both new locations) and this information can help you plan ahead if you have ash trees.
• Our landscape shrubs are probably growing beautifully right now and seeing some dead branches might drive us crazy (us = me), so know that while this is probably not the prime month for pruning, removing these dead canes can help. This pruning guide contains so much great information I’ve had to read it over more than once.

Lawn Care

• Our lawns are probably quite happy with all the moisture we’ve received, and let’s keep them thriving with proper care.
• Fertilizing can help if done correctly at the right time.
• If you are considering converting your lawn to less water-intensive landscaping, this info sheet contains a multitude of conversion methods and ideas.

Bunny in my garden, relaxing and digesting the flower leaves it just ate, grrrr! photo by Valerie Podmore

Perennial/Annual Flower Beds

• Both perennials and annuals can benefit from deadheading to promote more flowering and preventing them going to seed (if that’s what you want).
• Pull those weeds to prevent them taking over your flower garden!
• This document has a plethora of information about annuals and perennials during low-water periods because let’s be honest, we WILL get back to a lower water situation soon enough.

Oh, just one more thing (a la Columbo!), don’t forget that the “wonderful” Japanese Beetle will begin to make its appearance this month to destroy our hard work, so take a look at this article to learn more on this pest and how to battle it.

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

This Year’s Denver Extension Plant Sale Will Knock Your Socks Off

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

Denver Master Gardeners are again offering our friends and neighbors some matchless plant choices to kick off the growing season; be sure to save the date! We’ll be there regardless of the weather with not only great plants but also science-based gardening advice, so come on down! 

We’ll have a wide selection of vegetables and herbs grown by Denver Master Gardeners, along with an assortment of annuals and perennials.

All tomatoes, peppers, and other vegetables are $6.00. Annuals and perennials are priced as marked. Proceeds from the sale fund Denver Extension’s outreach efforts.

The vegetable and herb varieties offered are fabulous indeed:

Sweet Peppers
Ace Bell, California Wonder-Bell, Goddess Sweet Banana, Italian Marconi Red, Jimmy Nardello, Lesya, Nadapeño

Hot Peppers
Conquistador, Española Improved, Heritage Big Jim, Iberian Cayenne, Jalapeño Gigante, Jalmundo Jalapeño, Joe E. Parker, Las Cruces Cavenne, Lemon Spice Jalapeno, Mariachi , New Mex. Heritage Big Jim, NuMex Heritage 6-4 Chile, NuMex Joe. E. Parker , Passilla Bajio , Piñata Jalapeño, Poblano (Ancho), Primavera Jalapeño, Red Carribean, Sandia Select, Serrano, Shishito, Suave Orange, Vaquero

Heirloom Tomatoes
Abu Rawan, Amana Orange, Amish Paste, Arkansas Traveler, Black From Tula, Black Krim, Black Prince, Blondkopfchen, Brandywine Red, Burbank Slicing, Costoluto Genevese, Cour Di Bue, Dr. Wyche’s Yellow, Genuwine, German Pink, Gold Medal, Golden King of Siberia, Green Zebra, Heatmaster, Long Keeper, Martino’s Roma, Marvel Stripe, Marzinera, Minibel (Patio cherry), Mortgage Lifter, Orange Woodle, Principe Bourghese (Paste), Prize of the Trial (Cherry), Purple Calabash, Purple Cherokee, Red Fig (Lg. Cherry), San Marzano (Paste), Silver Fir Tree (Patio), Solar Flare, Stupice, Yellow Pear

Hybrid tomatoes
Ace Bush, Baby Boomer (Patio), Big Brandy, BushSteak (Patio), Celebritv, Cherry Sungold, Early Girl, Mountain Magic (Lg. Cherry), Red Beefsteak

Basil
Dark Purple Opal, Genovese, Italian Large Leaf, Sweet Italian, Thai Sweet Basil

Broccoli
DiCicco Heirloom, Belstar

Cabbage
Copenhagen, Michihili, Red Acre

Cantaloupe
Minnesota Midget Heirloom, Sarah’s Choice

Cauliflower
Purple of Sicily, Rober

Chard
Fordhook Giant, Ruby Red

Cucumber
Boston Pickling, Persian Gerkin, Marketmore, Space Master, Straight Eight, Arkansas Little Leaf

Dill
Fern Leaf

Eggplant
Black Beauty, Diamond, Fairy Tale, Gretel, Orient Express, Pumpkin on a Stick

Kale
Red Russian, Redbor

Lettuce
Cos-sunland (Romaine), Coastal Star (Romaine)

Milkweed
Showy

Oregano
Vulgar

Parsley
Giant of Italy, Moss Curled

Pumpkin
Cinnamon Girl (Pie), Duchess, Early Giant (Carving), Jill Be Little (Small decorating), Phat Jack, Rouge Vif D’Etampes (Cinderella)

Squash
Cube of Butter Summer, Delicata-Winter, Dunja-Summer, Honey Bear-Acorn Winter, Metro- Butternut Winter, Sunburst-Patty Pan Summer, Sunshine-Kobacha Winter

Tarragon
Mexican

Thyme
English Heirloom

Tomatillo
Grande Rio Verde (Heirloom), Purple Coban (Heirloom), Tomatillo Verde (Heirloom)

Watermelon
Blacktail Mountain, Golden Midget, Sugar Baby Heirloom

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We hope you’ll stop by for your favorite plants and try some new varieties too.

As always, please contact the Denver County Extension with your gardening questions. 

Low-Water Vegetable Gardening in Colorado

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

Water and vegetables go hand-in-hand. The more water you give to your growing vegetables, the bigger and better tasting the harvests tend to be. As water restrictions become common and conserving water becomes more important than ever, it’s going to be crucial for gardeners in Colorado to figure out how to resourcefully use water if they want to keep growing fresh vegetables.

There are a few key ways to cut back on water in the garden. Simple things like choosing vegetables that can survive (and even thrive) using less water, maximizing the water that you do use, and preventing water loss are all ways to keep your garden looking great without relying on excess water.

Chives are always the first thing to pop up in spring without any supplemental water. Photo by Felicia Brower

When it comes to choosing what to grow in your garden, it’s important to remember that different vegetables require different amounts of water. Vine crops need less water (and actually tend to be overwatered in the home garden), while beans and sweet corn typically need more water than other types of vegetables. Many perennial herbs don’t require a lot (if any) supplemental watering to do well. My parsley, chives, sage, thyme, and lemon balm are the first things to show up every year in my garden without any extra water to help them grow.

Not only do vegetables have different water needs, but some also need more water during certain parts of their life cycles. For example, peas need more water during their pod filling period while tomatoes need more water during flowering and fruiting. 

It’s also important to choose regionally-adapted vegetables. Vegetables that are selectively bred to excel in areas where drought is common are more likely to have fewer issues when they’re watered less in the home landscape. Search online for Colorado seed companies and choose vegetable varieties that are drought tolerant. While beans can often be huge water users in the garden, varieties like Zuni Gold, Paiute Gold tepary, and Sonoran White tepary are drought-tolerant and grow well without needing huge amounts of water. In fact, during some of my drier years, they stayed greener and kept producing while their neighbors wilted and struggled. 

Zuni Gold beans, a southwest Pueblo variety, are highly adaptable and drought tolerant, making them a favorite in my home garden.
Photo by Felicia Brower.

One of the best ways to conserve water is to maximize water efficiency. If possible, install in-ground drip irrigation or use cost-effective soaker hoses so that your water reaches the roots of the plants instead of being wasted on foliage or in spots without anything growing. Water at soil level near the roots in the morning, avoiding the heat of the day, to reduce the amount of water lost to evaporation and to avoid issues like powdery mildew on the leaves of your plants. 

Here are a few additional ways to grow a low-water vegetable garden: 

• Different soil types have different water needs, so water according to your specific soil type. Loamy soil needs deep, infrequent watering instead of regular, light daily watering while sandy soils need more frequent, less deep watering because they lose water faster than clay soils. 
• If you use overhead watering, don’t water your plants on very windy days. The wind will blow your water away and prevent it from reaching the roots. 
• Before you do any watering, test your soil’s moisture level. The surface of the soil might be dry but the roots might not be.
• Your garden layout can also impact how much and often you have to water your garden. Narrow rows need more water, so grow your veggies in beds, grids, or wide rows. 
• As with any plants in your home landscape, plant vegetables with similar water needs together. If you have a mix of drought tolerant plants and high-water plants, make sure they’re kept separate so you don’t overwater or underwater, both of which cause stress and can impact the quality of your harvest.
• Use mulch (green or otherwise) to keep moisture in the soil. You won’t have to water as much if you grow intensely (close together) or use another organic mulch to slow down evaporation. 
• Grow during Colorado’s shoulder seasons to take advantage of moisture from snow and spring rains and cooler temperatures, so there’s less water loss due to heat.
• Before you plant anything, take time to amend and prep your soil. Healthy soil retains water and is full of nutrients that prevent you from overwatering to try and make your plants stronger. 

As water conservation becomes more important in the west, it’s crucial to find ways to use less, especially for things like growing food. Follow CSU’s Colorado Vegetable Guide and the “Water Conservation in the Vegetable Garden” GardenNotes chapter for advice on best low-water vegetable gardening practices. 

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.