How to Grow Dahlias and Take Care of These Colorful, Long-Lasting Blooms

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Dahlias are gardeners’ favorite flowers, as they are relatively easy to grow and offer a great reward once they start blooming. Fortunately, they are pretty low maintenance and look great both in the garden and as cut flowers. Here is a short guide on how to grow dahlias and keep them blooming throughout most of the year.

Three Victoria dahlia blooms
Image source: Wikimedia Commons

Why Should You Grow Dahlias?

These pretty flowers are really common among most gardens due to their crazy look that everyone enjoys. Moreover, they can decorate your backyard for a long period. They start blooming at the beginning of summer, last until and throughout fall, and might still be in bloom as the first frost of the year takes over. In some areas, they might even survive winter, but this usually happens where it’s warm enough.

Even if they don’t last as long, growing dahlias in colder zones are also possible. You can give the plants a head-start by planting them inside first, and then take little extra care of them. If you learn how to grow dahlias anywhere, then you should easily achieve a garden full of beautiful flowers.

Choosing the Ideal Dahlias

Before starting the planting, you need to pick up the plants. There are many varieties of dahlia, having different colors and sizes. Depending on the garden you have, you might like one so that more than the other. This is why you should pay attention to this step before learning how to grow dahlias.

Dahlia Varieties

Dahlias are of three different types, depending on their size. They can be large when they reach about 3-4 feet in height. Therefore, if you choose this variety, you need to make sure you have enough space for them in your garden.

The second category includes medium dahlias that grow only 1-2 feet tall. They are also called border dahlias, meaning that they can edge other flowers and create beautiful garden arrangements. In the end, we have the small dahlias, which reach only 10-20 inches in height.

These varieties also include a series of colors. They vary from paler hues, starting from white, yellow, or orange, to bolder colors like blue, purple, red, or pink. Some breeds are multicolored, and sport petals in more nuances.

Purchasing the Tubers

To grow dahlias, you’ll need to plant their tubers. Although many people mislabel them as bulbs, the long, brownish formations are tubers. They don’t look much different from one variety to another, so you need to be careful. If you take the tubers from someone who has grown dahlias before, you can be sure how they will turn out.

If you buy them from a flower nursery, do not pick them up without reading the labels first. Also, ask for help if there’s something that isn’t clear. This way, you won’t risk purchasing a variety that is not suitable for your garden.

Bee in an orange dahlia bloom
Image source: PxHere

How to Grow Dahlias

Once you have purchased the plants, it’s time to get ready for the planting. Dahlias are pretty low maintenance and are not difficult to grow, so following all the steps should assure you a healthy and prosperous plantation. Here is what you need to pay attention to, and what you need to do during planting.

Choose the Soil

If you want your dahlias to grow healthy and sturdy, you should make sure the soil they grow in is suitable for them. The pH should be relatively acidic, between 6.5 and 7. You also need a spot with good drainage, that you can create for yourself. If the soil is too heavy to do the draining properly, you can mix some sand, manure, or moss in its composition.

Choose the Spot

The place where you plant the dahlias is really important for their growth. Dahlias need between 6 and 8 hours of full light during the day, so it’s important to find a spot where the plants can get direct sunlight. Also, make sure this spot is sheltered from the wind. However, depending on the area where you live, you might need to treat the flowers differently.

For instance, if you live in the south, where temperatures during summer reach incredibly high temperatures, dahlias might suffer a bit. They cannot cope with extreme heat, so it’s better to protect them from direct sunlight during this season.

Also, in colder areas, it’s hard for them to survive the winter. In some areas, it might be enough to apply a layer of mulch to keep the soil warm.

Choose the Right Moment for Planting

The time you plant the dahlias is extremely important. They don’t do well with cold soil, so take your time and wait until the weather gets friendly enough. You need to be sure there won’t be another frost that will come over your tubers. Therefore, May might be the ideal month for all the planting.

Prepare the Holes for Planting

Dig the holes where you are going to plant the flowers. When learning how to grow dahlias, make sure you know the proper treatments for each variety. Since they have different sizes, each variety will need a different spacing. The tall variety grows some big flowers as well, so you need to plant them three feet apart from each other.

The medium dahlias should stand only two feet apart from each other, while the small ones can grow anywhere between 9 and 12 inches apart from each other. However, this is not all you need to know about the planting holes.

Make sure you dig them big enough to fit the tubers. Measure the tubers first, as the holes have to be only a bit bigger than that. To make sure the plants will grow, mix some compost inside. This will give dahlias the boost they need.


When choosing the tubers, you will plant, pay attention to their looks. They shouldn’t look old, as this will reduce your chances of growing a sturdy plant. If you spot some green outgrowths on them, it means they are perfect for planting. Also, don’t use the same method you use when planting potatoes.

You shouldn’t cut the tubers, so introduce them in the holes without producing any damage. Place them with the growths up, at a depth of about 6 or 8 inches. This will allow these growths to stay up, and get beyond soil level.

Yellow dahlia with tiny petals in the center
Image source: PxHere

How to Care for Dahlias

Once the planting is done, you should make sure you allow the plants to grow. They will need some tending so that they can grow tall and beautiful.


You should wait until the first sprouts appear above the ground before watering the dahlias. Doing it before that might cause the tuber to rot. Then, once you see the germination has been successful, you can set up a schedule of watering twice a week. Use a big quantity of water, especially during hot summers and scorching days.


Thirty days after you have finished planting the dahlias, it’s time to apply some fertilizer that has a low quantity of nitrogen. Once the plants start growing, you should do the fertilizing treatment only once a month. Make sure you don’t add too much product, so opt for a fertilizer that is not soluble in water.

Protecting from Pests

The most common pests that attack dahlias are aphids and leafhoppers. You can easily get rid of them with a special soap for insects or isopropyl alcohol. Spider mites might appear as well during hot days, but these are easier to deal with. Just one spray of cold water should keep them away.

Powdery mildew might be one disease that attacks the plants. In this case, you’ll need a fungicide. Usually, this type of disease appears if the plants are not aerated properly, so make sure you give them more space. Some other fungi might start destroying the stems of the plant if you overwater it.

To get rid of the infection, you’ll need to remove the whole plant. When replanting, be careful with the soil drainage and the watering schedule. Mulch might keep weeds and other diseases away, so you can resort to this solution as well. However, make sure you don’t apply it directly at the stems.


This applies only to those varieties that grow tall, but it’s important to know of it when you learn how to grow dahlias. As soon as these flowers start growing, insert some stakes near them and tie the stems to these stakes. This operation is necessary, as the stems are too thin to maintain their weight and the weight of the flower if they get several feet tall.

Big dahlia bloom with purple petals with pink tips
Image source: Pixabay

Summing Up

Learning how to grow dahlias is mandatory for all gardeners. The plant is as popular as tomatoes or roses, and produce a great aesthetic effect on your backyard. They come in all sizes and colors, so it’s impossible not to find at least one variety that speaks to you. As long as you make sure the plant gets all the sun it needs and doesn’t freeze over during winter, your garden will look like a color wonderland full of dahlias.

Image source: PxHere

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