Vegetable Varieties New to Denver Master Gardener Plant Sale

Sale is this weekend, Sat., May 18, from 8 a.m.-3 p.m. and Sun., May 19, 10 a.m.-3 p.m.

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

An abundant and varied mid-summer veggie garden bed. Photo credit: Molly Gaines

If you’re like me, you probably have a go-to list of must-have vegetables for your garden: tomatoes, cucumbers, jalapenos, kale, zucchini, carrots, beets, basil, parsley and more. And while I love the predictability of tried and true varieties, each season I love planting something different and unusual. This helps me hone my vegetable gardening skills and keeps my garden fresh (no pun intended!) and interesting.

This year, find something old and something new at the Denver Master Gardeners (DMG) plant sale. We have a lengthy list of varieties that are new to the sale. See a full list of what will be offered here. It’s shaping up to be a perfect weekend for the sale! Come shop for all of your garden needs on Sat., May 18, from 8 a.m. until 3 p.m. and Sun., May 19, from 10 a.m. until 3 p.m. The sale takes place at 888 E. Iliff Ave., in Denver’s Harvard Gulch Park.

Veggies and herbs that are new to this year’s sale include: Kakai Pumpkins, Romanesco Cauliflower, Ace Bush Tomato, Tulsi Holy Basil, Ultra Cool Hybrid Watermelon, Hokus Cucumbers, Angel Hair Spaghetti Squash, Nasturtium, Dazzling Blue Kale, Haku Cabbage, Hale’s Best Cantaloupe, Taxi Yellow Low-Acid Tomato, Petite Yellow Watermelon, NMSU Scotch Bonnet Pepper, and Pueblo Chile. While we can’t cover them all in detail here, I’m going to share a little more about five of these new offerings for some planting inspiration.

Romanesco Cauliflower

Gorgeous Romanesco Cauliflower for sale at a farmer’s market. Photo credit: Molly Gaines

You’ve probably seen Romanesco Cauliflower at the grocery store or farmer’s market and marveled at its striking beauty. Get this plant in the ground ASAP, as it prefers cooler temps and takes 75-100 days to mature. Aphids and cabbage worms love Brassicas, including Romanesco. Consider companion plants, such as marigolds or basil, to fend off these unwanted pests. For more tips on growing Romanesco Cauliflower, visit here.

Ace Bush Tomato

Ace Bush Tomatoes are a great choice for our Denver climate as the fruit ripen early and can tolerate cooler temperatures. This tomato variety is determinate, which means the fruit will all ripen within 1-2 weeks, versus continuously producing fruit. Tomatoes in general are heavy feeders, and the Ace is no exception. For optimal growth and harvest, fertilize throughout the season. Here is a very helpful, comprehensive explanation of growing tomatoes in Colorado. It’s also worth checking out this interesting article about the best tomato and pepper performers for Colorado’s short growing season.

Nasturtium

Okay, I know nasturtium is a flower, not a vegetable. But no veggie garden of mine feels complete without this peppery, edible flower. The traditional varieties produce bright yellow and orange blooms. Deadhead to keep them rigorous throughout the summer months. I like to plant them in the corners or in front of my raised beds, as they spill beautifully over the top. They are not difficult to grow, but perform best in well-drained soil and full sun – minimum 6 hours. Provide these plants with good air circulation to fend off pests, such as aphids and caterpillars. For more on edible flowers, including nasturtium, visit here. I was surprised to learn how many edible flower varieties there are!

Nasturtium flowers are edible and make a colorful addition to garden beds. Photo credit: Molly Gaines

Petite Yellow Watermelon

Petite Yellow Watermelons are particularly well-suited for space-constrained gardeners. They are smaller than traditional watermelons, typically weighing between 2 to 4 pounds. This watermelon variety has a vibrant yellow flesh that tastes milder than red watermelon, but is juicy and sweet. These melons like it hot and sunny, so plant in full sun. Give plenty of space between plants, 2-3 feet, and fertilize regularly.

Pueblo Chile

Hailing from Colorado’s very own city of Pueblo, Pueblo Chile’s versatility make them a favorite among those who love peppers. They are mild to medium in heat and smoky in flavor. Plant seedlings in a full-sun location, 18-24 inches apart. They like well-drained soil. Keep soil moist and water at the base versus overhead as this can lead to fungal diseases.

We hope to see you at this weekend’s sale! If you can’t make it to our sale, keep these varieties in mind when you visit your local gardening center. As always, we invite you to visit the CSU Extension Yard and Garden website for more plant and gardening tips and to support you throughout the growing season. Feel free to reach out to the Colorado Master Gardener’s office with any gardening or yard questions: 720.913.5270.

2024 Denver Master Gardener Plant Sale – Saturday, May 18 & Sunday, May 19 2024 – An All-Weather Event You Can Count On!

By: Lori Williams – CSU Extension-Denver Master Gardener since 2016

The 2024 CSU Extension Denver Master Gardener Plant Sale features more than 150 of varieties of perpetual vegetable winners, including a huge selection of hybrid and heirloom tomatoes, delicious culinary herbs, and more than 25 chile pepper strains (sweet, hot, sweet-hot, hot and hot-hot)! For a full list of what will be offered, visit here. We offer gorgeous, healthy plants for your garden: many you’re likely familiar with and some fun new ones to get your garden possibilities growing! All veggies and herbs are $7 each. Annual flowers will also be available. Come early for best selection. Bring your own flat or totes if you can!

Renata Hahn, pictured here, is among the 50 volunteers who grew more than 150 plant varieties from seed (that’s 10,000+ plants!) for the plant sale!

With planting time just around the corner, many gardeners are looking forward to getting into the soil and chocking it full of robust bedding plants. Volunteers will be on hand to advise on varieties, planting practices and gardening in general – Ask US!! When you take your baby plants home from the sale, here are some important tips to first harden them off, as they will be fresh out of the greenhouse.

An exciting addition to the sale this year is a native plant selection. Five different species will be offered for $9 each, including: Large-Flowered Penstemon, Switchgrass, Mexican Hat, Butterfly Weed, and Evening Primrose. These are expected to go fast! With each plant purchased, native seeds will be given away (while supplies last). Salegoers can view a native garden planted last season, and the Front Range chapter of WildOnes.org will have a table.

Also during the sale, you’ll enjoy gardening demonstrations and an “Ask a Master Gardener” booth for your gardening questions. CSU Extension will have research-based resources for home gardeners, as well as education and nutrition information. New this year, Denver Master Gardeners will sell seeds for cool-season crops (like peas and spinach that can be direct sown).  A selection of native plants and perennials will also be offered!

Do you garden in containers or raised beds? Interested in interplanting veggies, flowers and herbs? Maybe you’ve been curious about block style garden layouts? Community gardens offer great gardening options, too. Our partners at DUG have all kinds of useful information here. Fresh vegetables and herbs will make you glad for the space and time you spend this season on growing fresh, flavor-rich, nutritious food for you and your loved ones.

Find all your faves & diverse new selections.

Denver Master Gardener volunteers are heroic in their commitment to get the healthiest, prettiest seedlings to YOU for your 2024 growing season – no matter the weather! A Colorado spring day can bring rain, sleet, snow, and sun – in no particular order. Regardless of temps, winds, or precip, our volunteers are excited to get these lovely bedding plants into your hands. We will be there, ready to help you! 

We look forward to seeing you May 18 & 19!

Maybe you’re also interested in becoming a Colorado Master Gardener? Come grow your experience and learn about the many gardening options, being a Master Gardener, and the amazing resources available to you through CSU Extension! 

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 April 2024

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

Last week’s snow covering forsythia starting to bloom. Photo: Molly Gaines

Signs of spring are everywhere in Denver. Daffodils, crocus and other spring flowers in full bloom one day; covered in ice and snow the next. Oh, to be a gardener at 5,280 feet!

While it’s too early to spend a lot of time planting, it’s a perfect time to prepare your soil, garden beds, tools, pots and lawn for the 2024 growing season. Below are a few gardening activities to consider before Mother’s Day, May 12 (around the safe zone from hard frosts) for planting most plants, flowers and vegetables.

Crocus are always a welcome first sign of springtime. Photo: Molly Gaines

As you plan your garden, it’s worth noting that some of the Denver metro is in a new gardening zone. Last November, the USDA announced updates to its “Plant Hardiness Zone Map,” updating this go-to tool for gardeners for the first time since 2012. The new map, which can be found here, places parts of Denver in Zone 6a rather than 5b. Zone numbers reflect the average extreme minimum temperatures and help determine what plants will thrive in each zone.  Higher numbers equal incrementally warmer low temperatures. For background about how to use this map as a planting guide, visit this helpful article from the National Gardening Association’s learning library.    

New USDA Plant Hariness Zone Map now places parts of Denver in Zone 6A. Credit: USDA

Vegetable Garden

• Clear remaining debris. Pull emerging weeds.
• When the soil is dry, add a fresh 2-3-inch layer of compost to your beds. This supports soil health and plant vigor. 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 planting.
• Plant frost-tolerant spring plantings, such as peas, spinach, arugula, radishes, Swiss chard, etc.
• Start indoor seeds for warm-weather vegetables such as tomatoes, peppers, squash, melons, etc.
• Reference this Vegetable Planting Guide to plan what you will plant when.

Trees & Shrubs

• The snowpack is solid Colorado-wide this year, well above 100 percent. This includes Denver. That said, if this month is dry, be sure to water your trees and shrubs.
• Early this month, prune deciduous trees, conifers and summer-blooming shrubs.
• Later in April into mid-May, prune rose bushes. For details on exactly how, why and when to do this, visit here.  This is weather dependent so watch for low temperatures and delay if a cold snap is predicted.
• Remove broken branches from trees and clear dead leaves and decayed fruit from the base.
• If you’re looking to plant a new tree, consider the Park People’s annual fruit and yard tree sale that begins April 20. Trees range from $50 to $80, and sales support the Denver Digs program. More details can be found here.  

Lawn Care

• Prep your mower, sharpening the blade as necessary and conducting other maintenance. Lawn mower blades should be sharpened at least once per season.
• If you use a pre-emergent weed product, apply in early April. For more details about how to use, visit here.
• Fertilize as desired, reading labels for proper application. Keep in mind that fall is the most important time for lawn fertilization. Applying only in the spring can mean excessive top growth and shallow root systems.

Perennial Beds

• Cut back perennial plants if this wasn’t done last fall, leaving 3 inches of the plant above the soil.
• Similar to your vegetable garden, the soil in these beds will also benefit greatly from compost, with the exception of native plants which generally prefer unamended soil.
• Pull emerging weeds now. Stay on top of them from the start.
• Divide overgrown perennials such as chives, sedum, grasses, phlox, daisies, hosta, etc. This will lead to healthier plants and better growth.

Other April Gardening Thoughts

• Assess garden supplies. Purchase or plan to borrow anything needed. Sterilize and sharpen garden tools.
• Empty any pots or containers still holding last year’s dead plantings. Clean and disinfect them to prevent disease in new plantings.

These pots need to be cleared of last year’s plantings, disinfected and filled with new soil for plantings. Photo: Molly Gaines

• Denver Water recommends waiting to turn on your irrigation until after the last freeze, typically in early May. Hand water until then.
• Sow wildflower and pollinator seed mixes.
• Prepare for frost, hail and other bad weather. Have sheets of plastic, old bedsheets and five-gallon buckets in easy reach for late-season snow or spring and summer hail. Remember the hailstorm that hit Denver late June last season?

Sad peas in a bed covered with hail. June 29, 2023. Photo: Molly Gaines

Springtime in Denver is special. I love watching new life slowly unveil itself. It’s a time full of promise, new beginnings and high anticipation of the color, flavor and textures around the corner. The more prepared you are in April, the more enjoyable your summer gardening season will be.

As always, if you have questions about plants, planting and any other gardening and yard related topics, visit the CSU Extension Yard and Garden website for 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.

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 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 August 2023

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

August is a fabulous month for enjoying your garden. Much of the work from earlier in the season will have paid off at this point. Since August is often hot and dry, it’s important to make sure your garden is getting the right amount of water, and to remain observant for stressed plants. Mark your calendar to get these gardening to-do’s done in your yard and garden.

Also this month and through September 15^th, CSU Extension is accepting applications for the next Colorado Master Gardener class. To learn more about our program, explore the resources at www.ColoradoMasterGardener.org and read Let’s Grow Together: Becoming a Colorado Master Gardener by Felicia Brower.

The vegetable garden at the Denver County Extension office. Photo: Merrill Kingsbury

A Yard and Garden Checklist for August

Vegetable Garden

• As your veggies ripen, harvest them, and if you cannot eat them right away, check out these good ideas to preserve them for later from Master Gardener Lois Margolin.
• How are your tomatoes doing? Growing tomatoes in Colorado can be tricky, with our wide temperature ranges and winds that prevent pollination. Some ideas for helping with your tomato problems can be found in this video on the PlantTalk website.
• Extend your gardening time by planting cool season vegetables such as peas, broccoli, and kale.

Trees and Shrubs

• Pay attention to signs of stress and desiccation in woody plants, and supplement with water as needed.
• Prune back summer blooming shrubs that have finished flowering, and that will bloom next year on this season’s growth. (It’s too late to prune spring blooming shrubs such as forsythia and lilac.)
• Always avoid trimming trees when they are water stressed by hot and dry conditions – they need to conserve all the energy they can this time of year.

Lawn Care

• During periods of high temperatures, a lawn may need as much as 2.5 inches of water or more per week.
• Mid to late August is a good time to over-seed bare spots in the lawn.
• The best defense against weeds in the lawn is thick and healthy grass, and you can encourage this by cutting the grass high – about 2.5 inches or higher.

Photo: Gail Leidigh

Perennial Flower Beds

• Some plants will start going to seed this time of year. If you don’t want the plant to self-seed, seed heads can be cut back. Or leave the seeds for the birds to enjoy.
• Weed ‘em and reap: Continue weeding the yard and gardens now, and reap the rewards later.
• Take note of what worked this year and what did not. Many perennials will be on sale at the end of summer and this fall, and it is a great time to fill in bare spots or replace plants that didn’t make it.

Annual Flower Beds

• Check the soil moisture in pots and hanging baskets frequently, as they will dry out quickly in the summer heat and wind.
• Clear and thin out plants that are fading, and make room for fall annuals that love the heat such as angelonia, ornamental kale, and daisy rudbeckia.
• Dead-head to encourage growth of new blooms.

Enjoy your garden this month!

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.