Easy To Grow Dahlias
Plan Now For Spectacular Summer Blooms
By Melinda Myers
Photos by Longfield-Gardens.com
Dahlias provide some of the garden’s biggest and most spectacular blooms. The flowers come in a rainbow of colors and many different styles and sizes, and all are excellent cut flowers. One of the best things about dahlias is how abundantly they bloom. The plants begin flowering in midsummer and produce more and more flowers each week, right through the fall. Just plant the bulbs in spring and prepare to be amazed!
STEP 1 – KNOW
START WITH A BETTER BULB
It’s easy to see the difference in a quality dahlia when you compare two plants side by side. Dahlia tubers are graded by size. Grade #1 tubers are the largest size available. Larger tubers give you a fuller plant with more stems and more blooms.
STEP 2 – PLAN
PLAN FOR SUCCESS
Dahlias are incredibly easy to grow. Here are a few tips to help you get the best results.
SUN AND SHADE: Dahlias are sun-lovers and need a minimum of 6 hours of sunlight per day. The more sun they get, the better they’ll bloom, so it’s best to plant your dahlias in the sunniest location you can.
ZONE: Dahlias are winter hardy in zones 8-11 (Houston area zone is 9a). They will grow quickly and the plants will be blooming by mid to late summer.
SOIL: Most plants, including dahlias, grow best in loose, fertile, well drained soil. To improve the quality of your soil, add compost and an all purpose fertilizer at planting time. Avoid planting in areas where the soil is soggy or compacted.
WHEN TO PLANT: Dahlias tubers are planted in the spring after all danger of frost. If you live in a cold climate and want your dahlias to bloom as soon as possible, you can start the tubers indoors about a month before the last frost date. Fill 6″ or 8″ pots with growing mix and plant one tuber per pot. Put the pots in a warm, sunny place until the plants are several inches tall and the weather outside is warm.
WHERE TO PLANT DAHLIAS
FLOWER GARDENS: Dahlias bloom from late summer through fall and hit their stride as most perennials are starting to fade. Consider each dahlia variety’s ultimate height when placing them in your borders, with tallest ones in back, mid-size dahlias in the middle and border dahlias up front.
ENTRYWAYS, PATIOS AND DECKS:
Decorate your home and welcome guests with a brilliant display of dahlias. Border dahlias are ideal for containers. The compact, bushy plants stay just 18″ tall and cover themselves with flowers from midsummer to frost.
ALONG FENCES OR FOR SCREENING: Dahlias can be functional as well as decorative. Full-size varieties can be planted along a property line to add privacy. They can also be planted in pots to enclose a space or in the garden to screen an unwanted view.
VEGETABLE GARDENS: Dahlias are great companions for almost any vegetable. Just plant them at the same time you’re planting tomatoes and peppers. When you harvest your dinner, you can also harvest fresh flowers for your table.
CUTTING GARDENS: Dahlias are fabulous cut flowers, and just a few plants will give you armloads of blooms. Planting several different flower styles will give your bouquets a professional look.
STEP 3 – GROW
PLANTING IS AS EASY AS 1-2-3
- Dig a hole to 4-6” deep in well-drained soil.
- Set the tubers in the hole with the stem facing up.
- Replace the soil and water only if the soil is very dry. Sprouts will appear in 2-4 weeks.
TIPS FOR GROWING DAHLIAS
- Choose a sunny spot. Dahlias bloom best in full sun.
- To give your dahlias the best possible start, improve the soil by adding compost and an all purpose (5-10-5) granular fertilizer when planting.
- Dahlia tubers should be planted 4-6″ deep. Position the tubers so the sprouts are facing up. If there are no sprouts, plant the tubers horizontally.
- Once your dahlias are 8-10″ tall, start fertilizing them with liquid fertilizer every two to three weeks.
- Pinching dahlias when they are about 10″ tall will give you bushier plants with more flowers. A video on how to do this is available on Longfield-Gardens.com.
- When the first flower buds appear, cut back a couple of the tallest stems. This will help the plant fill out and produce more flowers.
SUPPORT YOUR DAHLIAS
If you are growing full size dahlias, they should be staked to support both the stems and the flowers. Use at least one sturdy, 6-foot-tall stake per plant. Drive the stake into the ground 8 to 10″ deep. Inserting the stakes at planting time means you won’t damage the plant or tubers later in the season. As the stems begin to grow, tie them to the stake every foot or two.
GROWING DAHLIAS IN CONTAINERS
Dahlias grow well in pots and planters, either on their own or combined with other plants. Full size decorative dahlias and dinnerplate dahlias need to be grown in large pots. The bigger the pot, the less often you’ll have to water. For full size dahlias, the pots should be a minimum of 18″ deep and 18″ wide.
Border dahlias perform well in smaller-size pots that are a minimum of 12″ deep and 12″ wide. Fertilize your container-grown dahlias every few weeks and water them as needed — daily if necessary.
STEP 4 – AFTERCARE
CARING FOR DAHLIAS AFTER THEY BLOOM
Many gardeners treat dahlias as annuals. When the season is over, simply dig up the plant and the tubers and add them to your compost pile. If you want to save your dahlia tubers for the next growing season, here’s how to do it:
- When the foliage begins to lose its color or is killed by frost, cut off the stems to within 6” of the ground. Wait about a week before digging to give the tubers time to develop next year’s sprouts, also called “eyes”. Label each plant so you’ll be able to identify it next spring.
- Dig around the plant and gently lift the tubers from the ground, using caution as the tubers are fragile. Allow the entire clump to air dry for a week (protected from rain and frost). This gives the tubers time to toughen their skin for winter storage.
- Trim back the stems to 1″ and remove any fine root hairs from the tubers. Tag the base of the stems so you can identify the tubers later.
- Place each clump of tubers into a pot, bucket or bin and surround them with sand, sawdust or vermiculite. If you are putting multiple clumps in one container, layer them so they don’t touch each other. Store the container in a cool (40-50°F), dark place. Check the tubers monthly to make sure they are not rotting (too wet) or shriveling (too dry). Adjust the humidity accordingly.