How to Growing Dahlias for the Biggest Blooms

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If you’re looking to add some drama to your garden, then dahlias are the flower for you! These showy flowers come in a variety of shapes and sizes, and can be grown from both tubers and seeds. With a little bit of care, you can have yourself some massive blooms come summertime.

Growing dahlias may seem like a daunting task, but with a little care and attention, you can have beautiful blooms in no time. Dahlias thrive in warm, sunny climates and well-drained soil. After planting, water regularly and fertilize monthly to encourage growth. When the stem reaches about 12 inches tall, pinch off the growing tip to promote bushier growth. From mid-summer to fall, dahlias will produce an abundance of colorful blossoms. To extend the blooming season, deadhead spent flowers regularly. With proper care, your dahlias will provide you with beautiful blooms all season long!

So if you’re ready to up your gardening game, read on for tips on how to grow dahlias like a pro!

Disclosure: Some of the links below are affiliate links, meaning, at no additional cost to you, I will earn a commission if you click through and make a purchase. 

Choosing your plants-

Once you have decided to grow dahlias, the next step is choosing the right variety for your garden. Dahlias come in all shapes and sizes, so it’s important to select a plant that will fit well into your space. If you’re looking for big, bold blooms, go for varieties like ‘Bishop of Llandaff’ or ‘Cafe au Lait.’ If you want something a little more compact, try ‘T&M Impression Mix’ or ‘Bishop of York.’

Just pick a couple and get started! You will enjoy spectacular color, variety and abundance of blooms from mid-July through the end of the growing season.

Getting your plants-

There are several ways to get your first plants. Most major garden centers now sell dahlia tubers; that can be a very convenient way to get started.

Of course, there are also small businesses that specialize in selling dahlias and dahlia materials by mail order or internet. These suppliers are real experts on dahlias and their products are reliable and of good quality.

Here are some of our favorites:
Easy Grow bulbs

When to plant-

Your tubers can go directly into the ground in the spring when the ground has warmed and there is little chance of frost. One good guideline is to plant in the same time frame as you would a tomato. If you want blooms as early as possible, you can start the tubers indoors in good light about a month before planting time. You will then have a small plant ready at planting time. Dahlias can be planted as late as mid-June in most parts of the country.

Pre Sprouting Dahlias-

It can take 4 or 5 weeks for a dahlia tuber to sprout so if they are pre-sprouted, they are ready to start growing when you plant them.

All you need to do is take your dahlias out of winter storage and move them to a warm room that is above 55 degrees. You want to keep them in the storage medium as they do not need light to sprout, and you do not want them to dry out. Make sure your dahlia tubers are not too dry and shriveling. You also do not want them too wet and showing rot. You may need to lightly moisten your storing medium if it is very dry.

You can easily see the eyes on these tubers. If the sprouts are too long, just cut them back. They will send up more sprouts at that spot. You can see the crown of the tuber where the eye is forming, then the neck of the tuber, and the body of the tuber. Always remember that a dahlia tuber must have an eye to grow.

If you are storing your dahlia tubers in your garage or basement, as spring arrives and temperatures rise, your dahlia tubers will probably sprout in your storage container. If your storage area is really cold, then you may want to think about pre-sprouting the tubers by bringing them into a warmer room. When you are ready to plant, if your dahlia tuber has not sprouted just make sure you see like a little bump or pimple where an eye could form.

Dahlia tubers want to grow and are really resilient; however, they do need an eye to grow. If they are not pre-sprouted remember it can take up anywhere from 2 to 6 weeks for a dahlia tuber to sprout so be patient. Early bloomers are going to sprout first and late bloomers will take longer to sprout. Remember to plant your dahlia tubers when the soil temperature is around 60 degrees in the spring and all danger of frost has passed.

Where to plant-

Dahlias require a site with good drainage and full sun (at least 6 – 8 hours of sun).

Pots are also increasingly popular way to grow dahlias.

How to plant-

Dig a 5″ to 6″ hole, place my dahlia tuber in the hole with the “eye” on the tuber facing up, and place the soil back into the hole. The eye is the point on the shoulder, or crown, of the tuber from which the plant grows.

If you are planting a number of dahlias in the same location, they should be separated by about 2 feet to give each plant room to grow.

We use landscaping mesh when growing/planting our dahlia tubers. 9 inch holes are burned in the mesh. The holes are 12 inches apart across the fabric and 18 inches apart down the fabric.

You can learn more about using landscape mesh in our Cutting Garden Course. Learn More HERE!!

Protecting your plants from pests-

Small dahlia plants are susceptible to slug damage. It is a good idea to manually remove slugs early each morning or to protect them with a commercial slug killer.

Japanese beetles seem to enjoy eating dahlia blooms just when they are ready for a bouquet. One of the best methods of control is to manually remove the beetles into a bucket of soapy water.

Other insects can become a problem if you would like your blooms to be “perfect!” If that is the case, you might want to consider using an insecticidal soap or a commercial pesticide. Follow label directions carefully if you choose to do that.

Deer resistance-

The good news for dahlias is that they are low on the deer’s list of favorite foods. While dahlias are not “deer proof,” they are considered to be so in some parts of the country – probably those areas where deer find enough other plants they prefer to eat!

Watering and fertilizing-

Growing dahlias is not difficult, but there are a few things to keep in mind. For example, dahlias need full sun and well-drained soil. They also benefit from being planted in raised beds or hills to improve drainage. When it comes to watering, be sure to keep an eye on the weather forecast. If it’s going to be hot and dry, your dahlias will need more water. Conversely, if it’s going to be cool and rainy, they’ll need less.

When it comes time to fertilize your dahlias, use a balanced fertilizer like 10-10-10. You can apply it once a month during the growing season. Just be sure to follow the directions on the package, as too much fertilizer can damage the plants.

We love Epsoma Plant Tone and Dr Earth’s Flower Girl

Maintaining your plants-

For the simple enjoyment of spectacular dahlias in your garden, there are a few things that will enhance the appearance of the plant. First is tying the plant to the stake several times as it grows. The first tie should secure the lower portion of the plant’s stalk to the stake. Subsequent ties should secure the branches. A simple alternative to tying is to use a tomato cage to support the plant. Then, no tying may be required.

Second, pinch out the center shoot when the plants are around 12″ tall just above the third set of leaves. This is a one time pinch. If you do not pinch out the growing tip of the dahlia, the plant will grow without many side branches and produce one terminal bud. Pinching the center growth will result in a bushier, well balanced plant and produce many blooms until frost.

Learn more about pinching your plants HERE.

End of the season-

Your dahlias will continue to bloom prolifically right up until frost. A heavy frost will kill the plant and leave you with a decision on your next step. You can do nothing with the plant. You will then need to buy new tubers in the spring for the following year’s plants. Or, you can dig and discover that the plant has produced a half a dozen or more tubers like the one with which you started. If you wish, those tubers can be stored and grown next year.

Learn more about storing your tubers HERE.

If you’re looking for a fun and rewarding gardening project, why not try growing dahlias? These beautiful flowers come in a variety of colors and sizes, and are perfect for adding to bouquets or arrangements. Dahlias can be planted almost anywhere, but need plenty of sun and well-drained soil. They also require regular watering and feeding to keep them healthy and blooming all season long. By following these simple tips, you can enjoy the beauty of dahlias in your own backyard garden. For more information on planting, caring for, and harvesting cut flowers, check out The Cutting Garden.

The Cutting Garden

Our beginner gardening course for anyone who wants to grow beautiful flowers in their backyard and fill all of the vases in their home.

Learn More!