How to Grow Dahlias

Dahlias are an absolutely amazing addition to any garden, bursting with vibrant colors and a dazzling array of blooms! They're super easy to grow, making them a fantastic choice for gardeners of all skill levels. With their long flowering season, you'll enjoy a stunning display from summer right through to the first frost. Plus, their unique shapes and sizes create a captivating focal that will leave everyone in awe!

Tools you will need.

Dahlia tubers!

Hand trowel or shovel

Garden stake and twine

Soil amendments based on soil test

Sluggo Plus

Labels

Soil thermometer

Pre-planting

Dahlias often fail to grow when they are exposed to moisture before they have roots that are ready to use that moisture. The best way to avoid this is to warm up your dahlias before you plant them.

About 4 weeks before I plant my dahlias, I bring them into an environment that is about 65-72 degrees. This will trick them into thinking it is time to grow. Within a a couple weeks, depending on the the variety, the tubers will begin to push out a new growth point, or "eye," and will start to form roots. I also keep my tubers in sealed plastic bags or bins with lids with some sort of growing medium, like peat moss, coco coir, or potting soil, so the roots have something to hold onto.

It's planting time!

Another cause of dahlia failure is planting into cold soil. You want to wait until your soil is at least 60 degrees. A simple soil thermometer can do the trick, and there are also websites that can estimate the soil temperature for your zip code.

Once your soil is warm and your dahlias are pre sprouted, you are ready to plant. Be sure to pick a location with plenty of sunshine. However, in particularly hot and sunny areas, your dahlias will appreciate a bit of afternoon shade.

Lay your dahlia tuber horizontally in a hole about 4 to 6 inches deep. If the dahlia has already sprouted, the growth point should be facing the sky. But don't worry about it if there are multiple growth points, the sprouts will find their way up.

Before you bury your tuber, insert a garden stake into the ground close the growth point. Be careful not to damage the tuber. Then cover the dahlia with soil.

Watering at this point is tricky. If you live in a wet climate, you may not need to irrigate at all until the dahlia plant is visible above the soil line. Where I live, we get hardly any precipitation, so I irrigate sparingly at first. The point is to not let the soil become bone dry, and to avoid the soil getting too wet. It is a balancing act!

Finally, spread some Sluggo Plus on top of the spot where your plant is buriried. You don't want slugs and other grubs eating those tender shoots!

Growing beautiful dahlias.

Continue watering your dahlias regularly. A light rain is not going to cut it. You need to water deeply, once or twice a week, depending on your climate and soil. Sandy soil needs to be watered more frequently than heavy clay soil.

When your dahlia is about 12 inches tall, you have the option of pinching out the top growing point. Although this sets back blooming by a couple weeks, you will get a bushier, sturdier plant that produces more blooms throughout the season and is less likely to fall over. Additionally, if you are interested in cutting the flowers to bring into your home, this ensures that stems are long and slender.

As your dahlia grows, you will need to tie it to the garden stake with your twine about every 12 to 18 inches. Your heart will be broken if your dahlia plant is knocked over by a gust of wind. If this does happen to you, just cut the plant back and it will start to send up new stems shortly.

Be sure to snip off, or "deadhead," any spent blooms throughout the growing season to encourage the plant to continue to bloom.

Wrapping up the Season.

Inevitably, frost will come and your dahlia season will be over. A week or two after a hard frost (your dahlias will turn black and wilt) is the best time to dig your dahlias as the tubers have had a chance to "harden off," making them more likely to survive the winter in storage.

Cut down your plant and carefully dig your dahlia clump. Be super careful not to break any dahlias. Wash the dirt off your dahlias and now divide each tuber from the clump. You will want to store your dahlias in a cool and humid environment. About 40 to 45 degrees and 70-80% humidity. I prefer plastic totes with wood shavings. But there are lots of options depending on your climate.