Colorado Gardening Resources

Read our Q & A postings answering common Colorado gardening questions here. Keith Funk is handling these this year. You can also hear him on the Garden Wise Radio Show on Legends 810AM, every Saturday morning from 7-9.

Special thanks to Kelly Grummons for thoughtfully answering these questions for many previous years.

Have gardening questions? Click here to send us your question on our contact form. Use our search window below to find Colorado gardening questions & topics.

Tomato Plants Flowering but are not Fruiting

Q: My tomato plants are blooming but not setting fruit. What’s up with that?

Jul 311 min read

Bindweed Control without Herbicides

Q: Bindweed is taking over my lawn and gardens. What can I do without using synthetic herbicides.

Jul 312 min read

Refreshing Mulch

Q: I can see the soil through my mulch. I believe it’s allowing weeds to come up. Should I be adding fresh mulch this time of year?

Jul 311 min read

Adding Color to Perennial Flower Borders

A: First thing I do is go to the garden center and see what’s blooming there. My go to plants include the newer, dwarf, well behaved varieties of Russian Sage like Blue Jean Baby, Denim and Lace, and Little Spire.

Jul 311 min read

What flowering trees can I plant that don't attract Japanese beetles?

A: Here are some of my favorite flowering trees that Japanese Beetles avoid. Redbud, Yellowhorn, White Fringe Tree, Japanese Tree Lilac, Magnolia, Golden Rain Tree, Pagoda Dogwood, Cornelian Cherry Dogwood, Catalpa, Smokebush, Seven-Son Flower, Russian Hawthorne. Thoughtful selection will provide color from early spring through mid-summer.

Jul 311 min read

Specks on Cucumber Leaves

Q: My cucumber leaves have small silver specks on them. Is this normal or a problem?

Jun 301 min read

Fertilizers: Organic vs. Natural

Q: I see fertilizers labeled as “Organic Based.” What does that mean? What’s the difference between organic and natural? A: Organic fertilizers are made from materials that were once living, such as compost, manure, bone meal, feather meal, kelp, or alfalfa. Organic means the material contains carbon atoms. The nutrients are released slowly as soil microbes break them down, feeding both your plants and the soil. Natural fertilizers simply come from naturally occurring sou

Jun 301 min read

Hackberry “Pimples”

Q: My hackberry tree leaves have strange “pimples” on the underside of many of the leaves. Is this a problem?

Jun 301 min read

Deformed Hollyhock Flowers

Q: My hollyhocks have lovely flower spikes and flower buds, but they fall off or open with deformed flowers. I see small brown little brown bugs among the buds at the tip of the flower spikes. Are they the culprit?

Jun 301 min read

Is it bad to water the leaves of plants in the sun?

Q: I’m told not to get water on the leaves of my plants when the sun is out because the droplets act like a magnifying glass and burn the leaves. Is that true?

Jun 301 min read

Frozen Trumpet Lilies: Will they come back?

Lilium longiflorum (Easter Lily) Q: My trumpet lilies were up and growing beautifully until the freeze a few weeks ago killed them to the ground. What should I do? Will they come back? A: Yes — in most cases your lilies should come back just fine. A hard spring frost often damages the tender above-ground growth, but the underground bulb will survive. The leaves and flower buds turn black, mushy, or collapsed after the frost. Cut the damaged stems off at ground level. Do

Jun 11 min read

Why Do Roses Change Color?

Q: One of my roses doesn’t look like it has in the past. The color and size of the flowers is different and the leaves aren’t the same. What’s going on? Is it the weird winter/spring we’ve had? A: It could be weather stress from our strange Colorado winter and spring, but when a rose suddenly changes flower color, bloom size, and leaf shape all at once, there’s a very common explanation: your original rose may have died back below the graft, and the rootstock is taking ove

Jun 11 min read

Fastest Growing Vegetables to plant in June

Q: What vegetables can I plant in June that will give me a harvest yet this summer.

Jun 12 min read

Can Colorado Native Plant Gardens be Beautiful?

Natives from Left to right: Artemisia frigida (Fringed Sage), Berlandiera lyrata (Chocolate Flower), and the purple Penstemon strictus (Rocky mountain penstemon) Q: I read a lot about planting natives but they are difficult to find and not always that attractive, especially as a small plant in a pot in the nursery. How can I be environmentally responsible and still have a beautiful landscape? A: In recent years native plants have garnered more and more interest for the h

Jun 12 min read

Will my perennials survive the watering restrictions this summer?

A: More than likely they will. Some won’t grow as large or bloom as heavily, but they should all survive. Be sure to mulch bare soil to keep the soil cooler, reduce water loss and keep down weeds.

Apr 301 min read

Drought Resistant Potted Plants

Q: I love my patio pots of summer annuals but I know they need watering often. How can I keep my pots and still be water conscious? A: Plant in large containers (14” diameter and larger) as more soil holds more moisture. Avoid porous, terra cotta pots. Plant fewer plants in each pot to reduce the competition for the water. Choose lower water varieties like lantana, portulaca, verbena, gazania, cosmos, zinnia, periwinkle, dusty miller, gomphrena, and helichrysum. Plant mo

Apr 301 min read

Drought Resistant Vegetables

Culinary Mediterranean herbs like Sage are good low-water choices Q: I want to grow veggies this year but I’m concerned about the drought. Are there such things as low water veggies? A: During a drought, focus on growing deep-rooted and heat-tolerant vegetables like melons, potatoes, kohlrabi, sunchokes and Mediterranean herbs. Choose drought-resistant varieties and maximize water efficiency by using drip irrigation, thick mulch to reduce evaporation, and improving soil with

Apr 302 min read

Freeze Damage to Trees

Terminal buds after freeze Q: I’m worried about my trees after our recent freeze. A number of mine had started to leaf out and now the new growth is black. I’m also worried about my fruit trees. Did the freeze destroy the crop? Your trees will be just fine after the freeze. They have backup systems in place for this very situation. They know Mother Nature can be unpredictable so there are reserve buds to take over if the primary buds are damaged. Whatever you do, don’t cut

Apr 301 min read

Leaf miner on Spinach

Q: Every year my spinach gets leaf miner making the leaves inedible. How do I get miner free spinach?

Apr 32 min read

Where to hang bird houses

Q: When I install a bird house, should it be attached to a surface that doesn’t move, or is it okay to hang it from a branch.

Apr 31 min read

How to keep wasps out of birdhouses

Q: I have a wren house I want to put out this spring. Previous houses I’ve put up had wasp nests, I have heard of applying wax to the inside of the roof but haven't tried it. Do you have other suggestions?

Apr 31 min read

When to start tomato seeds indoors

Q: When should I sow tomato seeds indoors? A: Always check the seed packet. Most will tell you the number of weeks from sowing, to transplanting outdoors. As a very general rule of thumb, determine the date you plan to transplant your tomatoes outdoors in the garden and count back 6-8 weeks for your sowing date. For instance, I like to plant my tomatoes out Memorial Day weekend. This year it falls on May 25th. So my indoor sowing date will be the week of March 30th. For slo

Feb 261 min read

Fiddle Leaf Fig Care

Q: I was just given a fiddle leaf fig but have no idea how to take care of it. Can you give me some pointers?

Feb 261 min read

When to Prune Lilacs

Q: My lilacs are overgrown and need to be pruned back. When is the best time to do this? A: For spring flowering shrubs that flower before Memorial Day, pruning should wait until after flowering. They can be pruned earlier than that if you have no choice, but you will be sacrificing this spring’s flowers in the process. This would include shrubs like lilac, forsythia, quince, pussy willow, mock orange, most viburnums and spring blooming spireas. Flowering shrubs that flower

Feb 261 min read

Winter Watering in Colorado

Q: It’s been such a dry winter I’ve been watering my landscape about once a month. Should I water more often now? A: Good for you taking the time and care to winter water your outdoor plants. We have just been through one of the driest winters on record and the snow pack we rely on is severely lacking. It’s time to take a serious look at what that means for our landscapes this spring and summer.

Feb 262 min read

Garlic Sprouting in Winter

Q: I’ve noticed my garlic has sprouted some leaves above ground already. Is that a problem?

Feb 31 min read

Clematis Breaking Bud Early

Q: I know clematis like to start growing very early in the spring, but mine have already start to break bud. I’m assuming it’s due to our unusually warm weather this winter. How do I handle that?

Feb 31 min read

Clivia Plant Problems

Clivia Q: My Clivia plant of 15 years has been declining and no longer flowers. What could be the trouble? A: Clivias are beautiful, long lived houseplants known for their striking clusters of flowers and strap shaped leaves. They like bright, indirect light, well-draining soil, and infrequent watering, allowing soil to dry between waterings to prevent root rot. They also like a rest during the winter months to encourage spring blooms. Feed monthly during spring/summer with

Feb 31 min read

Wildlife Habitat Certification

Q: I’ve heard that homeowners can get their property certified as a Wildlife Habitat. How do I do that? A: In Colorado, you can certify your property as a wildlife habitat through the National Wildlife Federation (NWF) by providing food, water, cover, and places to raise young, using native plants and sustainable practices, with local support from organizations like the Colorado Wildlife Federation and Wild Birds Unlimited . Communities, schools, and businesses can also jo

Feb 31 min read

Feather Reed Grass Problems

Q: Three of my Feather Reed Grass clumps have fallen over sideways. When I went to clean them up, I noticed they were no longer attached to the ground. It looks like the tops were severed from the roots just below ground. What’s going on?

Feb 31 min read

Improving Your Vegetable Garden

Q: I’m going to attempt a vegetable garden one more time next spring. Every year, the results of my efforts aren’t very great. The root crops don’t get very big. The tomatoes get some disease and the squash always get mildew. Is this from bad soil or a bad gardener? What are some things I can do to improve our garden? If it doesn’t work out next year, I’m giving up. A: Oh no, don’t give up! I think if you boost your efforts just a little, you’ll have a much better crop next

Dec 4, 20252 min read

Bringing Succulents Indoors

Q: We love our succulent pots. We bring them indoors every winter. They are hard to keep healthy in our house. When I put them back outside in June, they are leggy and ugly. How can I do better with this? By the time they’ve recovered from their winter trauma, it’s winter again! A: Succulents are so popular and beautiful. When you bring them indoors for the winter, put them in as much sun as possible. If possible, keep them sunny and cool. A sunny mud room or extra bedroom w

Dec 4, 20251 min read

How to get indoor cactus to bloom?

Q: Over the last few years, I’ve collected a number of cacti and succulents. When I look them up online, it shows that they have gorgeous flowers. Mine never bloom. I have them in various windowsills and on tables near the window. Do they have to be older to flower? Do they need a certain kind of fertilizer?

Nov 5, 20252 min read

Some of the tropical plants I brought into the house to spend the winter are dropping leaves. What’s going on?

Tropical Croton plant Q: Some of the tropical plants I brought into the house to spend the winter are dropping leaves. What’s going on? A: It’s not unusual for plants to re-acclimate to indoor conditions when you bring them inside. Light levels are lower indoors and the air is drier. Give them time to adjust to their new conditions. Be sure to continue to feed them at least monthly through the winter to keep them as healty and possible. If they grew enough during the summer

Nov 5, 20251 min read

Mulching Perennials

Q: Does mulching my perennial beds help my plants survive the winter better? A: Absolutely – with one exception. Not only does it protect the root system from fluctuating soil temperatures, a 2-3” mulch also helps conserve moisture in the soil for good root growth until the soil freezes. I use the debris from my fall clean up once I’ve run it all through my shredder. A lawn mower will accomplish the same thing. I like it all chopped up because will decompose more quickly duri

Nov 5, 20251 min read

Is it too late to plant bulbs?

Q: Is it too late to plant spring flowering bulbs for next year? A: No, it’s not too late to plant bulbs right up to the time the ground freezes solid. This is a great time to find bulbs on sale at your local nursery. While the selection might not be extensive, any flowers are a welcome sight in spring. Be sure to water in your newly planted bulbs thoroughly and again in a month or so. They will start rooting out right away in preparation for spring and should not be allowed

Nov 5, 20251 min read

When should you use tree wrap?

Q: When should I apply tree wrap? A: The trunks of young, thin barked trees like maples, locust, linden and fruit trees will benefit from a commercial tree wrap to prevent sun scald for the first few winters. The general rule of thumb is ON at Thanksgiving, OFF at Easter. Read our Q & As with Keith Funk answering common Colorado gardening questions here. You can also hear him on the Garden Wise Radio Show

Nov 5, 20251 min read

Planting Mums in the Ground

Q: I received a beautiful big pot of mums as a gift. Can I plant these outside now? Just cut off the flowers & maybe separate into a few clumps?

Nov 5, 20251 min read

Should I remove all fallen leaves from my garden beds?

Should I remove all fallen leaves from my garden beds? A: Rake leaves from lawns to prevent snow mold, but a thin layer in garden beds can provide insulation and offer protection to overwintering wildlife.

Nov 5, 20251 min read

When to Harvest Winter Squash

Q: How do I know when my Acorn and Hubbard winter squash are mature enough to harvest and store well?

Oct 3, 20251 min read

Winter Watering Tulips & Daffodils

Q: I planted quite a few tulips and daffodils in September. Do I need to water them through the winter?

Oct 3, 20251 min read

Hydrangea paniculata 'Pinky Winky Prime'™. Photo: Proven Winners

When to Prune Hydrangea Paniculata

Q: I planted several varieties of Hydrangea paniculata this year and they were spectacular. Do I prune them now or in the spring?

Oct 3, 20251 min read

How to Correct a Leaning Tree

Q: My neighbors planted a plum tree two years ago. Over the past year and a half it started leaning over. They recently put some rope...

Oct 3, 20251 min read

Propagating Coleus

Q: I planted some pots of coleus last spring which have grown into beautiful plants. I’d like to keep them through for next year. They are too big to bring the whole plant inside. Are they easy from cuttings?

Oct 3, 20251 min read