To know them is to love them. They are show stopping flowers that come in an endless variety of colors, shapes, and sizes. They can be finicky, to say the least, so here are some tips on how we grow them here in South Louisiana.
Soil & Location
The tuberous root of a Dahlia, a.k.a. tuber, is what gets planted under ground (or in a pot). They have “eyes” that produce the vegetative growth for the dahlia plant. Tubers resemble a potato and resent heavy, clay soil. They like to be planted in loamy, well draining soil otherwise they will rot which results in permanent loss of the plant. Trust me on this, I’ve rotted my fair share.
For home gardeners, dahlias can be grown in a pot or in your landscaping. They need at least 8 hours of sun a day and keep in mind the tip about well draining soil. If you choose to grow your dahlias in a pot make sure there is a drain hole to allow water to escape. The good thing about growing dahlias in pots is that you can move them into the shade during a really hot, sunny day.
Water & Nutrients
When you first plant the tubers water them one good time and wait to water them again until you see vegetative growth. If you overwater the tubers they will rot. Once the plant sprouts make sure it gets a good watering every two to three days to keep the soil damp, but not soaked. As the plant matures Dahlias are heavy drinkers and heavy feeders. We use Neptune’s Harvest Fish & Seaweed Fertilizer to spray on the foliage of the plants to help accelerate vegetative growth. We follow the diluting instructions on the bottle and use a spray pump to administer it. We apply it once a week until the plants start to mature then we switch to Neptune’s Harvest Rose & Flowering Fertilizer once the plants start blooming. Fair warning, this stuff stinks, but it is a really good, organic fertilizer to use on any plant both inside or out!
When your dahlia plant reaches 12 inches tall and has at least three sets of leaves you’ll want to pinch the plant. Pinching is a technique that flower lovers use to encourage the production of more stems and blooms. It simply means to pinch, or cut off the top of the plant right above a set of leaves.
A few days after your dahlia is pinched you will see two little buds starting to emerge above the set of leaves. These will mature into stems and bloom flowers! Just like that you get 2 for 1!
It is also recommended to pinch dahlias because the stems are hallow. If you allow the dahlia to produce only one stem you will be left with a broomstick sized, hallow stem that will hold water and promote tuber rot.
Seasons & Bloom Time
The most important thing that anyone should know when trying to grow Dahlias here in the South is that they DO NOT LIKE THE HEAT. When you scroll through social media in the Summer or read up on articles online most flower growers have blooms in the Summer months. That is not the time of year that dahlias grow well for us southerners. They thrive on a “Sunny & 75” day which means they will bloom late April through mid-June and October through the first week of December for us. You can plant your dahlia tubers after the last frost in February for Spring flowers. If you miss that you can plant them again in August & September for Fall blooms. Keep in mind that after you see the first sprout on your dahlia it takes 8-12 weeks to fully mature.
Once your dahlias begin producing flowers you can harvest them to enjoy indoors! The more you cut the more blooms the plant will produce. This is the same for most flowering plants, unless it is a single stem producer like Pro-Cut Sunflowers. When harvesting always cut the stem above a set of healthy leaves. Just like pinching, two new stems will emerge and grow right above those leaves so you’ll have plenty more to enjoy. The first time you cut a flower from your dahlia plant you want to cut it deep. Follow the stem all the way down to the last set of health leaves and cut right above them. This will help promote tall stem growth for the next batch of flowers.
Even if you’d prefer to enjoy the flowers on the plant versus in a vase I suggest you follow these harvesting instructions so you can get the most out of them. The more you cut the more flowers will bloom. Once a dahlia blooms and lives its life cycle on the plant the flower will shed their petals and go to seed. This tells the plant to stop producing flowers and as this happens the plant will die back and regenerate for the next season.
One individual tuber will mature into a full clump over a growing season. You can divide the clump into various individual tubers to expand your collection of dahlias. I am no “pro” at this technique but I will say it is easier to spot an “eye” when the tubers are freshly pulled from the ground rather than when they have been stored and become dormant. I have linked a good article on how to divide tubers below along with other helpful tips on how to grow dahlias.
Let’s get to growing!
Dahlias are quickly becoming my favorite flower. Did I just say that out loud? There are just so many endless options to choose from that I simply cannot get enough. I hope you find these tips helpful for growing dahlias in the south! If you enjoy dahlias as much as I do feel free to share them with us! We love to see what you are growing. Also, if you run into a snag or have any questions don’t hesitate to reach out to us. We are always happy to help!
Here are a few of my favorite resources on all things Dahlias.