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Spectacular flowering dahlias draw consumers to garden centers every spring.
Dahlia tubers are widely available for purchase and it’s surprisingly easy to plant them yourself.
When to Plant Dahlia Tubers
Dahlias are warm-weather plants.
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Tubers need soil temperature between 60F and 75F to sprout.
Or start a month earlier in pots in a greenhouse or under grow lights.
Grow seedlings in pots until all danger of frost has passed before transplanting.
Dahlia tubers are perennial only in southern USDA zones 7 to 10.
In climates with hot summers, some afternoon shade is helpful.
Choose a spot sheltered from strong winds.
Work aged compost into the garden area or potting mix to increase nutrients.
The height of adahlia varietyinforms the best garden location.
Some types reach up to 5 feet tall and work best in back of the flowerbed.
Mid-size dahlias range from 30 to 40 inches, adding form and color to flowerbeds from mid-summer to autumn.
Allow space of 2 to 3 feet between tubers and other plants.
How Deep to Plant Dahlia Tubers
Planting depth depends on the size of the dahlia throw in.
Set tubers for tall varieties 6 to 7 inches deep.
Plant shorter varieties at depths of 2 to 3 inches.
A successful approach starts with digging a hole 12 inches deep.
Backfill with 6 to 9 inches of soil before setting and covering the tuber with the remaining soil.
Look for the eye which is similar to a potato eye and plant it facing up.
Cover the tuber with 1 inch of soil.
Once a sprout emerges, top off with another inch of soil.
Continue until the planting hole is completely filled.
This method helps stabilize tall stems, with additional support at the root level.
Install stakes at planting time to avoid damaging tubers.
Watering After Planting
Dahlia tubers require moisture to sprout but will rot in soggy soil.
Newly emerging plants won’t require much water.
Aim to keep soil evenly moist.
Give mature plants about 1 inch of water per week if rainfall is insufficient.
Potted dahlias need to be watered more frequently.
These are carefully lifted in autumn after the first frost and can be divided before or after storing.
Dahlias grow best from single stems and should be divided every year.
Some growers prefer to divide dahlias in spring when buds swell and are easy to see.
Cut back the main stem and store it with attached tubers in the same way as divided tubers.
Fundamentals of Growing Dahlias.American Dahlia Society
Dahlia (group).
