Blooms and Blossoms: A Guide to Planting for Stunning Colorado Spring and Summer Gardens

As winter bids farewell to the picturesque landscapes of Colorado, it's time for gardening enthusiasts to roll up their sleeves and embrace the beauty of spring and summer. The Centennial State offers a unique set of challenges and opportunities when it comes to gardening, with its diverse climate and elevation ranges. In this guide, we'll explore the plants that thrive in Colorado's soil and climate, ensuring your garden is a burst of color and vibrancy throughout the warmer months.


Native Plants: Embrace Colorado's Natural Beauty

Colorado is home to a rich diversity of native plants that have adapted to the local climate. Incorporating these plants into your garden not only ensures a thriving ecosystem but also requires less maintenance. Some popular native choices include:


Planting Instructions: Plant in spring, spacing plants 1 to 3 feet apart, depending on the variety. Prepare the garden bed by using a garden fork or tiller to loosen the soil to a depth of 12 to 15 inches, then mix in a 2- to 4-inch layer of compost. Dig a hole twice the diameter of the pot the plant is in. Carefully remove the plant from its container and place it in the hole so the top of the root ball is level with the soil surface. Carefully fill in around the root ball and firm the soil gently. Water thoroughly.

If sowing outdoors: In the early spring (3 to 4 weeks before the last frost)

Ongoing Care: Columbine is prone to a fungal disease called powdery mildew. The spores spread through splashing water and travel on wind currents to infect other plants. Once established, powdery mildew is difficult to control. Most fungal diseases develop during rainy, wet weather, but powdery mildew develops when daytime temperatures are warm and nights are cool. The disease is not dependent on water on the leaves. You can help your columbines resist the disease by cutting back the affected plant parts (down to ground level if necessary), providing afternoon sunshine, and lots of air circulation in and around the plants.


Planting Instructions: Plant dahlia tubers in spring after all danger of frost has passed and the soil has warmed. Prepare the garden bed by using a garden fork or tiller to loosen the soil to a depth of 12 to 15 inches, then mix in a 2- to 4-inch layer of compost. Dig a hole about three times as deep as the diameter of the tuber, usually between 3 and 8 inches. Set the tuber horizontally in the hole with the buds facing up, cover it with soil, and press firmly. Space most dahlia varieties two feet apart, but allow three feet for ones with large-diameter blossoms. Where the growing season is long, use 30- to 36-inch spacing for all varieties. When planting more than one row of dahlias, stagger them so that they don't shade each other.

Best time to plant: Late April to early May

Ongoing Care: Apply a 2- to 4-inch layer of mulch around dahlias to retain moisture and control weeds.  Dahlias prefer consistently moist soil, so water plants during the summer if rainfall is less than 1 inch per week, and water container-grown plants frequently to keep soil moist but not saturated. Remove flowers as they fade. 


Planting Instructions: Space plants at least 2' apart; avoid overcrowding, which limits air circulation and can lead to disease problems. The plants grow best in sandy soils with low fertility; you can add some compost at planting time but don't overdo it. In dry climates, a layer of organic mulch such as shredded bark helps conserve soil moisture. In regions with plenty of summer rainfall, skip the bark mulch to avoid root rot; instead, apply gravel mulch if desired.

Best time to plant: Spring to Fall

Ongoing Care: Besides a spring application of compost and occasional watering during dry spells, lavender needs little care. If your soil tends to be acidic, an annual application of limestone will keep the pH neutral. To harvest, cut the stems as soon as the first flower buds begin to open, secure them with a rubber band, and hang them up upside-down in a warm, dark place with good air circulation. To prepare plants for winter, prune the stems back in late summer and remove dead leaves around the base of the plant to promote air circulation. In ideal conditions, lavenders can live for many years; however, in most home gardens the plants may need replacing every few years.

Vegetables and Herbs: Tasty and Aesthetic

Don't forget to incorporate edible plants into your garden for a dual-purpose oasis. Many vegetables and herbs not only provide fresh produce but also enhance the visual appeal of your space:


Planting Instructions: Plant bush beans for an early harvest. Plant seeds 2 to 4 inches apart and 1 to 1-1/2 inches deep. Plant extra seeds, then thin plants to the spacing recommended on the seed packet. Pole (climbing) beans are slower to mature, but they have a longer harvest period. Set up trellises or tepees before planting. Plant seeds 2 to 4 inches apart and 1 to 1-1/2 inches deep.

Direct Sow Seeds: May 4 - Jun 1

Ongoing Care: Mulch bean plants to help retain moisture. Water plants during the summer if rainfall is less than 1 inch per week. Contact your local county extension office for controls of common bean pests, such as Mexican bean beetles and Japanese beetles.



Planting Instructions: Eliminate all weeds by repeated tilling. Loosen the soil to a depth of 12 to 15 inches, then mix in a 2- to 4-inch layer of compost. Prepare the bed by digging trenches 4 feet apart. The trenches should be 12 inches wide and 6 to 12 inches deep. Soak the crowns briefly in lukewarm water before planting. Draw a hoe along each side of the prepared trench to form a mound in the center running the length of the trench. Set the crowns 18 inches apart on the mounds in the trench, draping the roots over the sides. Cover the crowns with a mix of one part compost to three parts topsoil, burying the crowns 2 inches deep. Water the bed thoroughly. After about a month, once shoots have appeared, carefully add more soil to the trench.

Transplant Seedlings Into the Garden: Mar 20 - Apr 4

Ongoing Care: First year: Weed the beds frequently, taking care not to disturb roots. Periodically add more topsoil/compost around the emerging shoots until the trench is filled. Then spread a 4- to 8-inch layer of mulch, such as hay or leaves, around the base of the plants. Water regularly. Do not harvest any spears the first year. Cut down dead foliage in late fall and side-dress with compost.

Second year: Cultivate lightly by hand until the new spears are several inches tall. Keep the bed thickly mulched. Side-dress with compost in the spring and early fall. Cut down dead ferns in late fall. You may harvest very lightly the second year.

Third year and beyond: Maintain as for the second year, and begin harvesting.



Planting Instructions: For earliest harvest, start seeds indoors 6 to 8 weeks before the last frost date and set them out after 3 weeks. Sow seeds indoors 1/2 inch apart, 1/4 inch deep, in 4-inch-deep flats. Set out transplants spaced 3 to 4 inches apart for leaf lettuce, 6 to 8 inches for Cos and loose-headed types, and 12 to 16 inches for firm-headed types such as head lettuce. Plant seeds outdoors in beds or rows 1/4 to 1/2 inch deep. Plant heat-resistant lettuce varieties for late spring sowings, and choose a semi-shaded area to extend the harvest into the summer. Start fall crops in flats or directly in the garden in midsummer in northern states and in late summer in central and southern gardens.

Sow seeds indoors: Feb 24 - Mar 9
Transplant seedlings into the garden: Mar 23 - Apr 20
Direct sow seeds: Mar 23 - Apr 20

Ongoing Care: Mulch plants in early summer to keep the soil cool. Water plants during the summer if rainfall is less than 1 inch per week. Insects and diseases are rare in home lettuce plantings. However, contact your local County Extension office for controls of common lettuce pests such as slugs, earwigs and whiteflies.


With a thoughtful selection of plants that thrive in Colorado's unique climate, your spring and summer garden can become a dazzling display of colors, textures, and fragrances. Whether you're a seasoned gardener or a beginner, embracing the beauty of native and adaptive plants ensures a flourishing garden that withstands the challenges of Colorado's climate. Happy planting!



Contact me today with any questions: 

Kelly Thompson-Milner, REALTOR


[email protected]


Kelly’s Additional Credentials: 

Residential Construction Certified

New Build Specialist Designation

Work With Kelly

I have certifications and advanced training in residential construction of homes, new home builds, negotiations and understanding of title. I believe in taking care of my clients before, during, and after their home buying or selling experience.
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