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Dahlia Planting Guide for Zone 7: When, How & Basic Care

Dahlia Planting Guide for Zone 7: When, How & Basic Care

Dahlias are showy, colorful flowers that are related to sunflowers, daisies, and chrysanthemums. They are known for having a single, beautiful bloom on each flower stalk.

Many gardeners in Zone 7 want to include dahlias in their summer gardens but are not sure about when to do so.

When do you plant dahlias in Zone 7? If you are starting dahlias indoors, you can begin planting 4-6 weeks before the estimated last frost date. Since the last frost date for Zone 7 is approximately April 15, plant indoors from early to mid March. If planting directly in the ground, wait until after the last frost (late April and May).

Zone 7 has winters that are just warm enough for most dahlia tubers to survive dormancy in the ground.

Many gardeners take their chances by leaving the tubers in the ground and hoping for the best come spring.

Planting Dahlias in Zone 7

Zone 7 has the perfect summer weather for dahlias, but the plants cannot survive the cold winters.

Come spring, most people want to get dahlia tubers in the ground as soon as possible so they can enjoy the blooms.

Best Time To Plant Dahlias in Zone 7

The best time to plant dahlias in Zone 7 is late April and May. This is just after the fear of frost has passed.

By planting as early as possible in the season, you can expect mid and late summer bloom. 

If you want to start your dahlias indoors, you can begin planting the tubers 4-6 weeks before the last expected frost date (early to mid-March).

How To Plant Dahlias

Dahlias grow from tubers instead of seeds. You can save dahlia tubers from year to year, or you can purchase them from garden supply stores. Planting the tubers is quite easy.

Ideal Location

Dahlias love full sun in the garden. They should receive at least 6 hours of direct sunlight per day. The more sunlight they receive, the more blooms you can expect.

Preparing Planting Bed

Dahlias need loose, fertile soil that has good drainage. You can amend the soil with compost and balanced fertilizer before planting the tubers.

Planting Depth

You’ll need to dig a hole 4-6 inches deep to fit the average tuber. Once you cover the tuber with soil, the stem from the tuber should be 1 inch from the top of the soil.

Spacing

Dahlia plants can grow large and bushy. The plants should be at least 12-18 inches apart. 

When To Plant Dahlias in Pots

When planting dahlias in pots, use the same time frame as sowing directly in the ground. This means that you can start tubers indoors starting in early March.

For outdoor pots, plant the dahlia tubers after the fear of frost has passed.

Are Dahlias Annuals or Perennials

In Zones 8-11, dahlias are hearty perennials. They can also be planted as annuals in Zones 3-7. Dahlias will survive in Zone 7 until the first frost in the fall, which usually occurs around October 15.

If you wish to keep your dahlias from season to season, you can easily dig them up and overwinter the tubers in a frost-free location.

Several varieties of brightly colored dahlia flowers.

Dahlias Zone 7: Basic Care

Make sure that dahlia’s have fertile, well-draining soil. At planting, add compost or manure and a balanced fertilizer to the soil.

When the plants begin growing, pinch them off at 10 inches to encourage bushier growth. Most dahlias have hollow stems, so larger flowers will need additional support.

You can use stakes or cages for support. If you are inserting stakes (I like these sturdy steel stakes), install them when you plant the tubers so you do not damage the tuber or roots once the plant starts growing. 

Dahlia Winter Care

In Zone 7, most dahlia tubers can overwinter in the ground provided there is a thick covering of mulch.

However, many gardeners do not want to take the risk of losing their tubers, so they put them in storage for winter.

After the first frost, cut the stems down to a couple of inches tall. Wait a week or so for the tubers to go dormant. Then, gently dig the tubers out of the soil.

Allow the tubers to air dry for a couple of days. Cut all the stems down to 1 inch. Store the tubers in a container filled with sand or vermiculite.

Do not allow the tubers to touch one another in the storage container. Store the tubers in a cool, dry place until it is time to plant in spring.

Related Questions:

Can I Plant Dahlia Tubers in July?

July is too late to plant dahlia tubers in Zone 7. Since the season ends in early to mid-October, mid-June is the latest time you want to plant dahlias.

This time frame gives you enough time to enjoy the blooms before the growing season ends.

Are Dahlias Deer Resistant?

Dahlias are not truly deer resistant. However, they are known to be one the deer’s least favorite foods.

Since food is plentiful in summer, you most likely won’t need to worry about deer getting into your dahlias.

That’s a Wrap!

Living in Zone 7 gives you the perfect conditions to grow dahlias as annuals. The warm summers can help you yield plenty of flashy, gorgeous blooms.