Many people are scared off from growing dahlias. Some people try them, fuss over them too much, and decide they can’t grow them. Others are growing them for the first time and can’t wait to get started! I hope you are either already growing them, or you are in the last category mentioned.

Dahlias are really quite easy to grow. They are like any other plant: give them what they need and they will flourish. What do they need, you may ask? Dahlias need warm temperatures, lots of sunlight, well-draining and healthy soil, deep watering, and support. When you provide these basic things, you will be rewarded with some of the most beautiful blooms God created.

Temperatures

“When can I plant my tubers?” I get asked this question a lot. My answer is always the same: if it’s warm enough to plant your tomatoes, it’s warm enough for the dahlias. Just like tomato plants, dahlias like the soil to be warmed to about 60 degrees. If it’s too cool they can be more prone to rot. I don’t like to climb into a cold bed at night, and I’m betting you don’t either. So let that soil warm up a bit before you tuck those tubers in!

Another key factor I look at to determine when I plant my dahlia tubers is rain. If there is a significant amount of rain in the forecast, I would rather hold off another week or two rather than take the risk of having them rot from too much moisture. That may mean one year I plant at the beginning of May, then the next year I wait to plant until June. At least here in Missouri, that is one of the “joys” of our weather: you never know what you are going to get. Our only option is to wait and see and roll with the punches!

Gardening tip: Make a plan, but be ready to adjust your plan 1,372 times!

Sunlight

One of the best things for our health is getting unfiltered sunlight first thing in the morning. Dahlias love to wake up to the sun and pretty much spend the majority of their days soaking up those lovely rays. A little shade in the hot afternoon sun is ok, they don’t mind a little break, but if they are given too much time away they will sulk by hiding their blooms. A dahlia plant needs at least 6 hours of sunlight (preferably 8 or more) to give you the greatest amount of their glorious blooms. Too much shade reduces their energy, thus reducing the number of blooms they are able to send up.

Soil

Soil types can vary from one place to another, even on the same farm. Where we are located in central Missouri, our soil has quite a bit of clay in it. This isn’t ideal for dahlias, as it tends to hold too much moisture. We combat this by mixing in peat moss and rice hulls. This helps to keep our soil a bit looser, which also makes digging our clumps easier in the fall. Dahlias prefer their soil to be loose and well-draining.

Dahlias also like a healthy, fertile soil. Again, not all dirt is equal. The best plan of attack is to take a soil sample from your growing area. Once you have your results you will have a clear picture of what nutrients your soil is abundant in, and which nutrients it is lacking. However, if you are like me, you might say, “Ok, so what does this even mean. I can’t even decipher what the soil test is telling me!” Lucky for me, I hand it over to my husband and he tells me what we need to add to our soil. If you don’t have someone like this to help you, take your test to your local extension office, they are happy to help and will explain what you need to do to amend your soil.

Take time to sit and enjoy your efforts throughout the season.

Water

Water is a necessity for all living things. When you plant your tubers, they actually have everything they need stored inside until they are about 6-12 inches tall and have a root system. Unless you are extremely dry, hold off on watering your tubers until you have 6-12 inch plants. Then you can begin to give them a good drink about once a week. Again, dahlias remind me of tomatoes: they much prefer a deep drink once a week as opposed to a light drink every day. In the heat of summer, you may need to water more frequently; for us we sometimes need to water every 3 days or so if it is hot and dry. Pay attention to your plants and get your fingers in the soil to check for moisture! If the top couple of inches are dry, it’s a good sign your dahlias are getting thirsty.

Support

Now you’ve got the tools you need to get your dahlias growing well, so let’s switch over to a topical discussion: support. If you have provided everything else your dahlias need around their roots (or through their leaves!), you now need to think about giving them a support system. Dahlias have good strong stems, but they also have lots of blooms, and when that one storm pops up that sends its winds ripping through your dahlia beds, you want to be sure they will still be standing the next morning!

There are various ways to support your dahlias. If you plant them in rows, you can use posts at either end and tie string around both sides to keep your dahlias from falling over (use 2-3 rows of string 12-18 inches apart depending on how tall your varieties get). If you plant in singles, you can tie your plants to a garden stake as they grow, or use a tomato cage so you don’t have to worry about strings! We grow in 100 foot double rows, and have found it easiest to use T-posts and Hortonova netting. This allows the dahlias to grow up through the netting, and it keeps all the blooms and branches well supported.

Pinching & Deadheading

What a title! I promise we are not torturing our dahlias over here! Pinching refers to cutting off the top of the plants when they are about 12 inches tall. You want to make sure there are about 4 sets of leaves on the plant, then you simply snip off the very top. This will cause your plant to send out more branches from all of the “V’s” where the leaves connect to the main stem. What’s the point of this practice? By pinching, you will not only get a bushier plant, you will also get more blooms. It may delay flowering by 1-2 weeks, but the additional blooms are worth it in my book!

Dahlias branching from being pinched — The bright green shoots are the new growth after being pinched.

Deadheading refers to the practice of cutting of the spent blooms. Sometimes I love to enjoy the blooms outside, so I will leave them on the plant until they begin to wither. But this withering sends a signal to the plant that the season is over and it needs to begin putting all of its energy into making seeds. I’m not done with my season yet, though! If you cut the withering flowers off (and cut them down deep into the plant, leaving only a couple of sets of leaves from the main stem), you will signal to your plant that you want more flowers. We deadhead regularly to keep the blooms coming all season long. If you do want to try collecting seeds, wait until a little later in the season, then go ahead a let a few of those flowers go!

Dahlias are such a rewarding plant to grow. They take their fair share of work, but the most important thing to remember to do is enjoy the process; and of course enjoy the blooms! If you ever have any questions, please shoot me an email, text, or give me a call! I’d love to help!

Growing Dahlias