Question 1

What exactly are dahlia tubers?

Accepted Answer

They're tuberous roots (like a potato) that store water and nutrients to start the growth of a new dahlia plant identical to the parent plant. They're similar to potatoes in that the tubers multiply underground during the growing season.

Question 2

Are dahlias perennials or annuals?

Accepted Answer

Technically, dahlias are tender perennials meaning they'll grow back every year from their underground tubers as long as they don't freeze. Typically, this is in mild zones 8+ though those in slightly colder zones can overwinter them underground with lots of protective mulch to keep them from freezing.

Most of us in zone 7 and below, however, grow dahlias as annuals—digging up and storing the tubers over winter to plant the following spring.

Question 3

What’s the difference between dahlia plants and tubers?

Accepted Answer

Tubers are planted to grow new plants. Plants sold at garden centers were grown from tubers or cuttings and will bloom sooner.

Question 4

Does tuber size or shape matter?

Accepted Answer

Not much. As long as a tuber has an eye, crown, neck, and body, it will grow—whether it’s curved, small, fat, big, or skinny.

On our farm, we plant the smallest and “ugliest” tubers ourselves and send the "prettier" ones to you.

That said, the resulting plant from an “ugly” tuber will be identical to one grown from a “pretty” tuber.

Question 5

Can dahlias be grown from seed?

Accepted Answer

Absolutely! However, unlike tubers or cuttings—which are exact clones of the parent plant—dahlias grown from seed can produce unpredictable results.

Why? Because each seed in a dahlia head needs to be pollinated individually. That means one dahlia seed head can have hundreds of different pollen parents. You can’t know exactly what you’ll get when growing dahlias from seeds which is why if you want a specific dahlia variety, you need to grow it from a tuber or a cutting.

Question 6

When is the dahlia blooming season?

Accepted Answer

Dahlias typically start blooming in mid to late summer and continue flowering until the first frost.

Question 7

Where should I plant my dahlias?

Accepted Answer

Dahlias prefer full sun for about 6 - 8 hours a day. If you live in a particularly hot climate, however, they'll appreciate late afternoon shade.

Question 8

How to prepare my soil to grow dahlias?

Accepted Answer

Well-draining soil is a must. Dahlia tubers are prone to rot in soggy soil that doesn't drain properly. To improve poorly draining soil, add lots of organic matter like compost, aged manure, or shredded leaves to break up dense soil and create air pockets. You could also consider using perlite or vermiculite.

If you have heavy clay soils (I grew dahlias in Georgia before moving to Utah so trust me on this), you'll either want to grow them in raised beds or you'll want to add plenty of organic matter to lighten up the existing soil. I did both—loosened the soil down to about 12" then mixed tons of rotted leaves to the existing soil—leaving me with a slightly raised bed to plant my dahlia tubers into.

The pH level of the soil should be nearly neutral at 6.5 - 7.0. If you need to make adjustments, adding lime increases your pH level, while adding sulfur decreases your pH level.

Regardless of where you live, I highly recommend sending in or dropping off a soil sample to your local county extension office before you plant so you know your soil's pH and exactly what amendments your soil needs to grow the healthiest possible dahlias.

Check out our blog post on Soil Testing to learn more!

Question 9

Are dahlias deer resistant?

Accepted Answer

Not really—deer will eat dahlias, especially if food is scarce, but they’re not usually a deer’s first choice.

Question 10

Do dahlias need to be staked?

Accepted Answer

Yes—most dahlias need support because the plants grow tall and those gorgeous flowers can be heavy! Individual stakes or tomato cages work well for a small number of dahlias. For a larger number of dahlias, I recommend corralling them with t-posts and twine.

Question 11

How do I plant a dahlia tuber?

Accepted Answer

I answer this question in detail in the "Dahlia Care" tab here on my website. Check under the "Planting" heading.

Question 12

How much water do they need?

Accepted Answer

I answer this question in detail in the "Dahlia Care" tab here on my website. Check under the "Growing" heading.

Question 13

How to harvest dahlia flowers for continuous blooms?

Accepted Answer

I answer this question in detail in the "Dahlia Care" tab here on my website. Check under the "Harvesting" heading.

Question 14

What do I do with my dahlias after the first frost and everything's black?

Accepted Answer

I answer this question in detail in the "Dahlia Care" tab here on my website. Check under the "Digging & Dividing" heading.

FAQs

Frequently Asked Questions