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  • Writer's pictureKassi Kuppinger

Your Ultimate Guide to Summer-Blooming Bulbs: 4 Bulbs to Plant in Spring

As spring arrives and the garden bursts into life, it's the perfect time to start planning for a summer filled with stunning blooms and vibrant colors. Summer-blooming bulbs, with their dazzling array of flowers and easy-care nature, are a fantastic addition to any garden. In this guide to summer-blooming bulbs, we'll explore everything you need to know, from the best varieties to plant in spring to essential tips for planting and care. Whether you're a seasoned gardener looking to expand your bulb collection or a beginner eager to add some beauty to your outdoor space, this guide has you covered. Get ready to unleash the beauty of summer!

bulbs for sale at local garden center

What Are Spring (Summer-Blooming) Bulbs?

The world of bulbs can be somewhat confusing. If you have done much research on flowering bulbs, we are sure you've heard of spring bulbs, fall bulbs, spring-blooming bulbs, summer bulbs, summer-blooming bulbs, and who knows what else. We are going to simplify things. In general, there are two main categories of flowering bulbs: Spring-blooming bulbs (also referred to as fall bulbs), and summer-blooming bulbs (also referred to as spring bulbs).

crocus growing through snow in spring

The first category includes bulbs that can tolerate cooler temperatures and bloom in the spring. These bulbs are planted in the fall, as they require a period of cold temperatures in order to bloom. These bulbs include things such as tulips, crocus, daffodils, etc., and they are referred to either as fall bulbs (pertaining to when they should be planted) or spring-blooming bulbs (pertaining to when they bloom). Once planted, these bulbs will reemerge year after year in the early spring, gracing your yard with an early pop of color. In this blog, we will refer to this category of bulbs as spring-blooming bulbs.

summer blooming bulbs

The other category includes bulbs that are not tolerant of cooler temperatures and bloom in the summer. These bulbs such as dahlias, gladiolus, and cannas, among many others, are planted in the spring once any chance of freezing temperatures has passed. These bulbs are not tolerant of cold temperatures, so they are either planted as annuals or need to be dug out of the ground at the end of the season and stored indoors to be planted again next spring. These bulbs are often referred to as spring bulbs (pertaining to when they should be planted), summer bulbs, or summer-blooming bulbs (both pertaining to when they bloom). For the purposes of this blog, we will refer to them as summer-blooming bulbs.

When To Plant Summer-Blooming Bulbs

Summer-blooming bulbs are planted in the spring and bloom in the summer. Since these bulbs are not able to withstand cold temperatures, it is important to make sure the soil temperature has had a chance to warm up and there is little to no chance of freezing temperatures. Generally, mid-to-late May is when it is safe to plant summer-blooming bulbs. This is around when the average last frost date for Norther Colorado is, and is tyically the same time of year that other garden plants like tomatoes, peppers, and squash can be planted in your gardens.

How To Plant Summer-Blooming Bulbs

Planting summer-blooming bulbs such as dahlias, gladiolus, and others is a fairly straightforward process. By following these steps, you can plant your summer-blooming bulbs with confidence.

1. Choose the Right Location

Select a planting site that receives ample sunlight, as most spring bulbs thrive in full sun. It will also be very important to ensure the soil is well-draining. Spring bulbs are sensitive to moisture and can easily rot if the soil becomes waterlogged, so take the necessary measures and amend your soil appropriately to encourage good drainage.

2. Prepare the Soil

Use a garden fork or shovel to loosen the soil to a depth of 10-12 inches. Mix organic matter such as compost into the soil to improve its texture and fertility. You can also mix fertilizer specific to bulbs such as bone meal into the soil to encourage strong and healthy growth and bigger blooms. If your soil is extremely dense and clay-heavy like much native Colorado soil is, consider digging it out and replacing it with potting soil. This will give you a better foundation for all your current and future planting endeavors.

3. Select Your Bulbs

Choose high-quality bulbs from a reputable supplier. Your local garden center will have varieties that are suitable for your climate and growing conditions. Do your best to inspect the bulbs for signs of damage or disease, discarding any that appear soft, moldy, or shriveled. Bulbs in this state will be unlikely to grow strong and healthy.

4. Planting Depth and Spacing

Follow the planting depth and spacing recommendations specific to each type of bulb. Generally, larger bulbs are planted deeper than smaller bulbs. The planting depths specific to each type of bulb will be listed on the back of the packaging, however, as a general rule of thumb, plant bulbs at a depth that is approximately three times their diameter. Space bulbs according to their mature size and growth habit for best growing results!

5. Planting Technique

Dig individual holes or prepare a trench for planting your bulbs. Place your bulbs in the soil with the pointed end facing upward and the roots facing downward. Cover the bulbs and gently tamp the soil down around them. You do not want to compact the soil too much, but you do want to make sure that there are no air pockets and that the amount of soil covering the tops of the bulbs is adequate.

6. Watering and Mulching

Water newly planted bulbs thoroughly to settle the soil and provide moisture for root establishment. If the soil sinks in around the bulbs, fill in the area with more soil. Apply a layer of organic mulch such as bark chips to help retain soil moisture, suppress weeds, and regulate soil temperature.

7. Maintenance

Monitor soil moisture levels and water bulbs as needed, being aware of water needs during particularly dry periods. Fertilize bulbs with a balanced fertilizer according to package instructions to promote healthy growth and flowering, and remove any spent flowers or dead foliage to maintain a tidy appearance and prevent the spread of diseases.

8. Overwintering

In Colorado, our winters get too cold for tender summer-blooming bulbs to survive. If you would like to preserve your bulbs for next year, you will need to carefully dig them up in the fall before freezing weather sets in. Be careful not to damage your bulbs as you dig them up, as damaged bulbs may not survive the off-season. Store your bulbs in a cool, dry location with good air circulation, checking them periodically for signs of rot or decay. Come next spring, you can repeat the process of planting your summer-blooming bulbs and enjoy them all over again!

What Bulbs To Plant in Spring

Many different types of flowering bulbs make a beautiful addition to any garden. Some of the most popular include dahlias and gladiolus, though here is a list of some other favorites you may want to consider for your garden this season.

1. Dinner Plate Dahlias

Dinner plate dahlias are prized for their massive, dinner plate-sized blooms. They can grow up to four feet tall and are fantastic for attracting pollinators such as bees, butterflies, and hummingbirds to your flower gardens.

2. Cactus Dahlias

Cactus dahlias are known for their striking, tubular petals which resemble cactus spikes. They come in an array of bright colors, can grow up to four feet tall, are a favorite among pollinators, and like most dahlias, they can also be grown in containers!

3. Gladiolus

Gladiolus grows tall spikes of flowers that can reach up to nearly five feet tall! Coming in single-color varieties or varieties that feature multiple colors, these summer-blooming bulbs are deer-resistant, pollinator-friendly, and some are even winter hardy, which means you don't have to worry about digging them up and storing them for the winter season.

4. Colocasia

A relative of the alocasia family, these topical plants make great additions to annual flowerpots or planting beds throughout the growing season. Their large leaves can come in multiple colors and patterns, and they can also be brought indoors and grown as houseplants throughout the winter season.

Browse Summer-Blooming Bulb Options at Bath Garden Center

At Bath Garden Center, we have tons of summer-blooming bulbs for you to add to your flowerbeds this spring. Shop our full selection in-store, or browse limited items online! Spring is the time to plant your summer-blooming bulbs, so don't wait. If you have questions about planting or would like more guidance, find hands-on tutorials on our YouTube channel or reach out to us with your questions.


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