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How to Grow Dahlias

Dahlias: How to Plant, Grow and Care

Dahlias are among the flowers that require the least maintenance. Dahlias have the highest production of cut flowers and garden plants that can grow. In a good year, they bloom in the late June and early December season (fall or the beginning of winter), especially if given proper care. Learn How to Grow Dahlias from Seeds, plant, and care for them.

how to grow dahlias

When to Plant Dahlias

Mid-April to May

These multi-colored pointed-up flowers come in all shapes and sizes, ranging from 5 cm pompons to large ones like 20 cm. Most grow at least a meter or meter and a half high.

How to Grow Dahlias from Seeds

Although not suitable for extremely humid and hot climates, Dahlias will brighten any sunny garden for at least 120 days. They do best in cool, humid climates, where blooms can be a few inches larger. Here the tips on how to grow Dahlias.

How to Grow Dahlias from Seeds

Dahlias are beautiful perennials, very easy to grow both in the garden soil and in pots. There are many different species and many cultivars of a wide variety of colors and shapes.

If you like gardening, consider planting dahlias. We tell you everything you need to know about their care, during each season, so that in summer you can enjoy their beautiful flowers.

Dahlias Flowers

Process of Planting Dahlias

The key to how to grow Dahlias is the season. For best results, they should be planted from mid-April to May. They need a sunny spot to thrive, an area that receives at least 8 hours of direct sunlight.

Consider these Recommendations Before Planting:

Soil temperature should be around 60 degrees

The pH should be 6.5-7.0, slightly acidic.

Well-drained soil for sowing

An open place with wind and sun protection

If the soil is heavy, try adding sand, moss, or manure to soften and loosen the soil texture so that better drainage is obtained.

Since dahlia is a perennial plant grown from small brown tubers, it is recommended to avoid those that appear wrinkled or rotten. A good sign that you will get a great crop with those that show a little green growth.

how to plant dahlias

How Deep to Plant Dahlias

When sowing the whole tubers, with growth points or small “eyes” try to leave them upwards, at least 5 to 8 inches (15 to 20 cm) deep. Wait for the sprouts to appear on the ground to water.

The big ones and cultivated exclusively to be cut are better cultivated in plots located in rows, free of other plants.

The medium-low height plants mix better with other summer flowers. If you only have one garden, it’s the perfect place to put a row of this beautiful little tree.

If you have a grown bed, it can be planted at a safe distance. The smaller types, which grow about one meter high, should be spaced two meters apart. As long as they are taller and have big flowers, their space should be at least two and a half meters.

To Plant a Grown Bed:

    The hole should be larger than the root ball

    Incorporate compound or moss into the soil

    You can also add some bone to the planting hole

    Once you enter, do not water

    Fill the hole with soil or compound

When they are tall and large-flowered they require support. It is recommended to place stakes around the plants at the time of planting and tie them to the stems while they are growing.

Once the planting procedure has been completed, taking into account the considerations we share with you, you will be able to see your garden blooming after a few weeks, especially during June.

how to prune dahlias

How to Plant Dahlia Bulbs

Everything you want to know about How to Plant Bulbs.

Care for Dahlias

They are sensitive tubers. There is no need to water the soil until the flowers of the plant appear. Excess water can cause the tubers to rot. Once they are established, their care is very simple when a care routine is established.

Provide deep watering 2 to 3 times per week for at least 30 minutes with a sprinkler, especially in hot, dry climates.

Nourish them with low nitrogen liquid fertilizer, similar to that used for planting vegetables

Fertilize after sprouting and then every 3 to 4 weeks from summer to fall season

how to grow dahlias in pot

Pinch the growth point to encourage sprouting

This will not only increase your growth of leaves and flowers, it also increases the group of roots or tubers that will help you enjoy the beautiful view with more colors in the next flowering season.

With a well-prepared bed of soil, they will grow beautifully and quickly.

Final Tips for Grow Dahlias and Care for.

They flower an average of 90 days after planting. If it is your first time sowing, or you are an expert gardener, you will know that some advice or recommendations are never too much to get a good result with the planting done.

Although by nature they grow quickly, not all of them manage to do so at the same speed. Remember these tips before you give up:

When planting, make sure you dig deep holes and work the soil around them

Avoid over-fertilizing, you run the risk that the tubers will rot or you will not see them bloom

For the large ones, insert the stakes at the time of sowing

When they are large they may need additional attention before or after the rainy season

If the winter is not too severe, cover them with deep, dry fertilizer

Avoid leaving them in the garden when the winter is severe and there is snow

The best time to cut the flowers is in the fresh mornings

Once you do the process, you should have no problem enjoying them in the garden now that you know how to do it.

how to grow dahlias garden

The Dahlia: How to Grow

The dahlia is a very appreciated flower for its ornamental beauty, both in the garden and for cut flowers.

It is a low maintenance plant, which offers a large production of flowers for the few cares it requires and grows in lush bushes that bloom from early summer to late autumn with the first frosts.

But the plant does not die with the cold, its tuberous roots can easily withstand frosts of 10 F (-12ºC) and even lower temperatures if protected with good padding during the winter.

dahlias bulbs seeds pot

It goes without saying that in my region, next to the Mediterranean, there are no problems in this respect.

The genus Dahlia belongs to the family of Asteraceae and there are many types. Some are herbaceous plants and behave like perennials, their aerial part disappears in winter and sprouts again the following season. Others are shrubs and perennials, developing a strong root system in the form of tubers.

They are native to the mountains of Mexico and Guatemala, where the Aztecs used them as culinary and medicinal plants. The Dahlia coccinea is one of the oldest species, a simple but very colorful flower that grows on rocks and roadsides in its natural habitat and from which most of the cultivated dahlias come.

dahlias flowers

Origin and History of the Dahlia

The first references that exist about the dahlia appear in the 16th century and come from the writings of Francisco Hernandez, doctor of the court of Philip II in a scientific expedition to New Spain to observe the natural resources of the Spanish colony.

In the work “History of the Plants of New Spain”, Hernandez describes two species of dahlia known to the Aztecs as Acocotli and Cocoxochitl, very similar to the dahlias that are cultivated today. But the first Dahlia seeds did not arrive in Europe until the 18th century, specifically in the Royal Botanical Garden in Madrid where they were grown and selected to produce the beautiful hybrids we know today.

dahlias flowers

It was first described by the botanist Cavanilles, Director of the Garden, who sent seeds of Dahlia pinnata to the main European botanical gardens.

Care for Dahlia

In the same way, beetles and spider mites can eliminate not only the leaves but also the flowers of the dahlia. To avoid them, use a spray recommended for your plantation. Like Lilacs, these flowers are covered by a dusty white mold that can be controlled with a bicarbonate spray.

how to grow dahlias

Soil for Grow Dahlias

Dahlias need fertile, light, and well-drained soil so that water does not stagnate at the roots. Dahlias like the soil to be slightly moist and cool. They are not very demanding when it comes to the pH of the substrate, it is enough that it is of a neutral level. The ideal is between 6.5 and 7.

soil for dalhias

Light for Grow Dahlias

Dahlias thrive best in sunny places. In cool climates they can be in full sun all day, in warm climates, it is preferable to avoid the intense afternoon sun which can quickly wither their beautiful flowers.

how to grow dahlias


At the beginning of the season, it is not necessary to water the dahlias until the first shoots appear. Established plants need deep watering twice a week in the spring, when summer arrives and they start to flower, they should be watered more often.

how to plant, grow and care for dahlias


It is very important that when dahlia plants awaken from their winter dormancy they find a nutrient-rich environment to feed on and grow vigorously. For this reason, at the end of the winter, we will add a layer of organic fertilizer to the surface of the soil where the plant is.

This organic fertilizer, which can be worm humus, manure, or any other natural fertilizer, besides being ecological and very rich in nutrients, improves the structure of the soil and the plant grows better.

In summer, to encourage the production of flowers, we are interested in fertilizing with a fertilizer rich in potassium and low in nitrogen that we will apply diluted in water every fifteen days.

How to Grow Dahlias and Combine with other Flowers

Not all combinations of plants work well and I do not mean only on an aesthetic level. The roots of the plant, under the soil, compete for nutrients and can steal the food they need from those around them. Therefore, you have to combine plants that can absorb water and food with similar capacities. These are some plants that will get along well with our dahlias:


    Lilies (Lilium)

    Goldenrod (Solidago)



how to plant, grow and care for dahlias potted

How to Grow Dahlias in Pots

Growing Dahlias in Containers

The dahlias are magnificent plants to cultivate in pots. They adapt very well because they do not need soil as deep as other shrubs, but it must be a pot of at least 30 cm of diameter and as much depth.

Before planting the tuber we should fill the container with a universal substrate to which we will incorporate three or four handfuls of organic fertilizer, we will introduce the tuber to about 15 centimeters and we will cover with the substrate.

potted dalhias

Then we will give a copious watering that we will repeat twice a week until the plant grows. It is much more advisable to water rarely and in-depth than to water very often with light watering.

This changes when the plant starts to flower, so we should water more often. In summer, in hot climates, it will be necessary to do it every day.

how to plant, grow and care for dahlias black dalhias

How to Grow Dahlias in the Garden Soil

If you want to grow dahlias in the garden, follow the above planting tips by digging a hole 30 centimeters in diameter and as deep as. Introduce a good substrate, fertilizer, and tuber.

If the soil of your garden is very clayey, it is advisable to add some sand to make it more permeable.

how to plant, grow and care for dahlias

If you plant several tubers to make a good mass of dahlias, leave a separation between them according to the final size of each plant so that air can circulate and avoid the appearance of fungi (mold).

how to plant, grow and care for dahlias

How to Prune Dahlias

Dahlias are very appreciated for making bouquets because they are very decorative. To promote the production of side shoots on the stems of the plant and to produce more flowers, clip over the third set of leaves on each branch. They say that dahlia flowers last longer if they are put in very hot water after cutting and left to cool.

Cutting Flowers and Pruning

Remove the wilted flowers from the plant. If you leave them, the energy of the bush will be focused on producing seeds and the production of new flowers will decrease.

If you are interested in large flowers, remove all the side shoots so that only one flower forms at the end of the stem. A well-cared-for dahlia plant produces flowers without stopping until the first cold weather arrives.

How to Grow Dahlias and Prepare the Division of Dahlia Bushes

Dahlia tubers can be divided in spring or autumn. Remove the tuber from the ground as gently as possible and use a sharp knife to cut it. Ideally, separate pieces that already have stems to ensure that they will develop into a new plant, but even the pieces without stems may thrive.

how to plant, grow and care for dahlias

How to Grow Dahlias: Cultivation Calendar

Early Spring

It is a good time to divide the tubers

It is time to plant in pots or the garden soil if it is no longer cold

Plant the tubers at a depth of about 15 centimeters

Water moderately once planted and do not water again until the plant sprouts

Fertilize with a liquid fertilizer 5-10-10 when the plant exceeds 5 centimeters in height

how to plant, grow and care for dahlias


Continue fertilizing with fertilizer 5-10-10

Remove weeds around the plant

Observe and control the appearance of pests

Late Spring

Cover with a layer of mulch to prevent water evaporation

Increase watering if it is too hot

Stake the tall varieties to avoid breaking the stems

Pinch the stems to promote the production of more flowers

Remove the side shoots if you want fewer flowers but larger

Observe and control the appearance of pests

how to plant, grow and care for dahlias


Continue with the same care described above

Extra care with the appearance of fungi


Remove the tubers if the cold of winter does not allow to keep the plants in the garden. It is a good time to divide them

If the weather permits, leave the tubers underground by covering them with an extra layer of mulch

Remove all foliage that has fallen to the garden floor

End of Season Care

In places, with very strong frosts it is convenient to remove the tubers from the soil and store them until the next season.

Before taking them out, the leaves and stems should be allowed to wither completely.

how to plant, grow and care for dahlias

Once dug up, the tubers should be cleaned of adhering soil and stored wrapped in newspaper in a dark, dry and cool place. All old leaves that have fallen to the garden soil should be removed.

Dahlia: Pest and Diseases

Surprisingly, they get rid of most pests. However, they can be a real magnet for slugs and snails. With very little time, they can do a lot of damage to the plantation. It is recommended to apply bait to them every two weeks after the sowing and to continue during all the season.

The dahlia, discovered by the Aztec Indians, conquered the Old World with its beauty, and during the two hundred years of subsequent history, thousands of new cultivars were produced with genetic improvements to produce a huge variety of sizes, shapes, and colors.

To control this situation and keep any damage out, be vigilant so that your nursery is free of pests or diseases that can ruin it.

White Powder on Dahlia Leaves

If you see a white powder appearing on the stems or leaves of the plant it is a sign that air is not circulating well between the branches of the dahlia.

This whitish powder is powdery mildew, a microscopic fungus that thrives on moisture and heat. To remove it you can spray the plant with sulfur and prevent it from appearing, give the plants more space to have better air circulation.

Grasshoppers can also be a problem, they love the tender leaves of dahlias.

You can scare them away with a preparation based on a mixture of one tablespoon of isopropyl alcohol and another of potassium soap in half a liter of water.

Sprinkle the plant with the preparation at intervals of 3 to 5 days until you notice that the grasshoppers stop coming.

how to plant, grow and care for dahlias

Dahlias are part of the favorite menu of snails and slugs. Lemons are difficult to eradicate, but you can put traps around the plants to catch them so they don’t destroy your dahlias: beer traps, ashes, or eggshells.

Some chemicals will kill them, but they are pure poison and I do not recommend them.

About Julia Morgan

Julia Morgan is an agronomist and a master gardener. In her previous roles, Julia was an advisor promoting large-scale food growing in urbanized areas, introducing the concept of chemical-free produce. She is an expert in putting her hands in the soil, developing organic foods, and improving production processes for decades. Julia is a natural teacher and encourages every person in her way to grow their own food. She split her days between writing and reviewing for The Garden Style Website and offering assessments to cure edible land. Julia enjoys connecting with The Garden Style Community.

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