Growing Dahlias in the South: A Starters Guide

Introduction

My foray into dahlias (pronounced “dal-ya” around these parts) started in 2017. I saw pictures of Sweet Nathalie online and immediately fell in love with the light, creamy pastel colors. I originally wanted to grow them for my daughter’s wedding, but discovered getting dahlia tubers isn’t as easy as visiting your local farmers market. If you are new to dahlias, you’ll find that popular varieties will sell out almost as soon as they are available. Although I was late to the party, I had to have them in my garden and made plans to secure tubers for the following year. I soon found out there are very few people growing dahlias in the Southeastern US. I nearly gave dahlias up after I read articles suggesting they couldn’t tolerate our climate. Typically, dahlias do not like the humidity and heavy rainfall we get in the summer. Red clay, a staple in the North Carolina Piedmont, doesn’t drain well. However, my dahlias have been resilient. Here are some things I’ve learned about growing dahlias down South.

Site Prep

Fortunately, I’ve been at this for a while. My garden is better suited for dahlias than most who are just starting. Ideally, soil needs to be loosened, cultivated and amended as dahlias will not grow in hard, packed clay. Dahlias prefer the pH level to be slightly acidic at 6.5 to 7. Consider having your soil tested. I test yearly and have brought my soil pH up from 4.5 – 5 by adding dolomite lime that was given in the analysis recommendations. To keep your soil rich, add organic compost and leaf mulch each year. Additionally, I add sand and gypsum to aerate the soil as much as possible.

A raised bed with compost is a good option for those without the time or patience to prep the ground. Some counties will offer compost at little or no cost through their respective cooperative extension office. So, be sure to check. Otherwise, any potting soil will do, as long as it’s organic. If you are attempting to grow dahlias in a humid climate such as ours, you’ll want to pick a spot that avoids the hottest part of the afternoon sun. Dahlias need at least 6 hours of full sun, but planting where they’ll get some relief prevents wilting.

Fertilization

I’m 100% organic and I do not use chemical fertilizers. However, dahlias are heavy feeders and need adequate nutrition. I add bone meal to the rows before I plant. Espoma makes a wonderful organic bone meal. I love their products, especially their Bio-tone starter fertilizer with Mycorrhizal. Warning: bone meal will attract dogs and coyotes. They’ll dig up your rows trying to get at it. This can pose problems if your garden isn’t fenced.

Planting

Another potential problem with growing dahlias in the South, the one I struggle with the most, is identifying the opportune time to plant. We get a lot of rain in the spring. I’ve learned to pot my tubers in small containers with potting mix and wait until early-mid May to plant. By May, the roots and sprouts are prominent and ready to start taking up rainwater. Doing it this way also eliminates the risk of a late frost.

Spacing

My double rows are 3’ apart. Within the row, I plant tubers 15″ apart. This allows for more air circulation as the dahlias grow. Without proper spacing, the leaves will not dry promptly after a rain and can lead to mold and fungus.

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Pinching

One of the most difficult techniques to master when growing flowers, especially dahlias, is pinching. Once your plants are 8-12’ in height, you need to take sharp pruners and cut out the top 3 – 4”, above a leaf nod. This causes the plant to stay smaller and increase its productivity. Since the stems are hollow, I do this when rain isn’t expected for a few days.

Pests

There’s a never ending battle with insects in the South. Slugs, snails, earwigs, aphids, leafhoppers, spotted cucumber beetles, Japanese beetles, etc. can all cause problems. If you garden, you deal with bugs! However, you also have good bugs in your garden that feed on bad bugs. Also, song birds and lizards love to stop by our gardens for a meal. I don’t use any insecticides. Instead, I hand-pick the bad bugs I can catch. I use Sluggo Plus for the slugs that like to eat my tiny seedlings, but nothing ever gets sprayed or applied to the garden. I’m ok using snail bait underneath straw because it limits the about of pellets birds or “good bugs” inadvertently eat. I am contemplating adding ducks to my farm for additional slug control now that I have my garden completely fenced.

Ready to Grow Dahlias?

I love, love, love my dahlias and I’m so glad to have them in my garden. Hopefully this article proves helpful if you’re intent on growing dahlias in the South. You’ll want to tailor these recommendations based on your climate, soil conditions and the variety. I look forward to hearing your success stories!

Happy gardening! Please leave your questions and feedback in the comments section below.