When To Plant Cactus Dahlias

Quick Summary


FROM DIRECT SUN TO PARTIAL SHADE Dahlias are rooted in tuberous roots that can withstand cold temperatures up to Zone 6. They are native to the Highlands and Central Plateau of Mexico. Star Elite may be the most exquisite cactus dahlia on the market right now. The enormous 7-8 in. diameter blossoms feature a strong salmon pink rim around a lemon yellow core. Each petal has a slender, pointy tip and a variable curvature. Plants can grow up to 42 inches tall.

Dahlia tubers should be planted in fertile, friable soil in the late spring when the risk of frost has passed. Remove all but 1-2 upshoots from the largest flowers. Deadhead frequently and drink water. Till a heavy frost destroys the plant, dahlias will continue to bloom lavishly all through the summer and into the fall. Dig the tubers once the plants have withered back, then store them somewhere cool, dry, and dark.

One dahlia per pot with a 14-inch diameter makes dahlias excellent container plants. They will need frequent watering and fertilization every two weeks with a potent potassium and phosphorus fertilizer.

Which month is ideal for dahlia planting?

Dahlias are delicate perennials that are planted in the spring and grown from tubers. The secret to cultivating colorful, healthy dahlias is to plant them in the late spring once soil temperatures reach 60 degrees F since dahlias do not thrive in chilly soil. Wait till after the last spring frost date in your area as a general rule. Some gardeners plant dahlia tubers in pots in April or May (approximately 4-6 weeks before their last spring frost date) because this may be in late May in many northern regions of the country, and then transplant dahlias to the garden once the risk of frost has passed. You’ll get to enjoy dahlia blossoms sooner in the summer by doing this.

How are cactus dahlias planted?

Do you need assistance planting cactus dahlias? A booklet chock full of pointers and recommendations on planting, arrangement,

The unusually formed summer flowers on this eye-catching species of cactus dahlias are what set them apart.


  • About eight weeks after planting, dahlias begin to bloom.
  • A month beforehand, some gardeners begin tubers indoors in containers.
  • Up until the dahlia plants emerge, the soil doesn’t need to be watered;
  • Dig up dahlias and keep them in a warm place in regions with intense cold.
  • In the summer, spray a heavy potash fertilizer every few weeks to

Can I plant dahlias after Labor Day?

Dahlias are simple to grow and produce lovely flowers from the middle of summer until the end of the season. Dahlia cultivation and tomato culture are comparable in many ways. Dahlias can be effectively grown in your yard if you can grow tomatoes. You may enhance your garden with stunning blossoms and vibrant color by using the tips below!

Choosing your plants

Dahlias come in a wide variety of hues and shapes. On this website, there are a lot of examples. You can choose based on the images you see here, the images on the bags, or the recommendations of a dahlia friend. Just choose a few, and begin going! From mid-July through the end of the growing season, you can enjoy dazzling color, diversity, and profusion of blossoms.

Getting your plants

Ohio’s Dahlia Society is preparing for its plant auction. Robert Leonelli’s image

Your first plants might be obtained in a variety of ways. Dahlia tubers are now sold in the majority of large garden centers; this can be a very practical method to start.

Almost all dahlia societies host tuber and plant sales, and attendees are welcome. If there is a club nearby, this strategy has a lot of benefits (see list on this site). The possibility to get professional guidance on your decisions is perhaps the biggest advantage of that supplier of tubers or plants! This professional guidance can be continued throughout the season because a Q&A session is a frequent component of many of our community society meetings! A society auction will probably have high-quality, locally-grown tubers as well.

Of course, there are also tiny companies that focus on selling Dahlias and Dahlia-related products through the mail or online (see supplier list on this site). These vendors are true dahlia experts, and their goods are dependable and of high caliber.

When to plant

In the spring, when the ground has warmed and there is little possibility of frost, you can plant your tubers straight in the ground. Planting in the same window of time as you would a tomato is a useful rule of thumb. The tubers can be started indoors in good light about a month before planting time if you want blooms as soon as possible. At planting time, you will then have a little plant ready. In most of the country, dahlias can be planted as late as mid-June.

Where to plant

Sites with good drainage and partial to full light are necessary for dahlia growth. Dahlias are also becoming more and more common to grow in pots. For further details on dahlia cultivation in pots, see other pages on this website.

How to plant

The majority of dahlias need to be staked, therefore you might wish to place a strong stake first. If you bury the stake after the plant has begun to grow, be careful not to sever the tuber or the root system. A basic method of staking can also be done with tomato cages.

With the “eye” (which resembles a potato sprout) pointing up, place the tuber in a hole that is several inches deep. The point on the shoulder or crown of the tuber where the plant emerges is called the eye.

Dahlias should be spaced apart by about 2 feet when planted together to allow for adequate growth for each plant.

Protecting your plants from pests

Slug damage is possible to little dahlia plants. Slugs should be manually removed in the early morning hours or protected with a slug killer product.

Just before dahlia blossoms are ready to be arranged in a bouquet, Japanese beetles seem to enjoy munching on them. Manually removing the beetles into a bucket of soapy water is one of the best ways to control an infestation.

If you want your blossoms to be “perfect,” other insects may become a nuisance. If so, you might want to think about applying a commercial pesticide or an insecticidal soap. If you decide to do that, carefully follow the instructions on the label.

Organic Approach

Dahlias respond favorably to an organic gardening style. They have plenty of flowers, some of which are very huge, and they are vigorous, powerful growers. Even in the absence of chemical fertilizers, they thrive in soil that contains significant amounts of organic matter. Although not absolutely necessary, pest control can be carried out successfully without the use of chemical pesticides.

Deer resistance

Deer damage to our suburban gardens and vegetation is becoming more common. Dahlias have excellent news because deer don’t consider them to be one of their favorite foods. Dahlias are not “deer proof,” but in some places of the country—likely those where deer can find enough other plants to eat—they are said to be!

Watering and fertilizing

Young dahlia plants don’t require a lot of water; in fact, too much water can cause the plant to rot. A good general rule is to water larger plants if the rainfall is less than an inch in seven days. Pots need to be watered more frequently.

The ideal approach to fertilizing is to start with a soil test to identify the pH and the unique requirements of the soil. In the absence of that knowledge, the plants will often benefit from routine applications of a granular or water-soluble fertilizer. Dahlias should be fertilized with a high nitrogen fertilizer throughout the center of the season but with a low nitrogen fertilizer at the end of the season, according to conventional knowledge.

Maintaining your plants

Maintaining plants for spectacular blooms can be done with a thorough routine. Two comparatively easy steps can improve the appearance of the plant, allowing you to just enjoy the magnificent dahlias in your garden. As the plant grows, the first step is to tie it to the stake multiple times. The plant’s bottom stem should be tethered to the stake using the initial tie. The branches should be fastened with additional ties. Using a tomato cage to support the plant is an easy substitute for tying. Then, tying might not be necessary.

Disbudding is the second. From the three buds that form at the end of each branch, remove the outer two. Even when the overall quantity of flowers is decreased, many flowers are still present and still look good on the plant. The blooms will typically be hidden and may be lost in the plant if all three buds are left on the stalk. You can also cut off a few of the branches that grow along the branch so that you have stems for tall vases filled with classy bouquets.

End of the season

Up until the first frost, your dahlias will continue to blossom profusely. A severe frost will kill the plant, leaving you to decide what to do next. Nothing can be done with the plant. For the plants for the following year, you will then need to schedule a trip to the neighborhood auction in the spring. Alternately, you can dig and find that the plant has produced six or more tubers similar to the one you started with. If you like, you and a few pals can save those tubers and grow them the next spring! For information about harvesting and storing your tubers as well as other issues addressed on this page, visit Dahlia University.

How soon may dahlias be planted?

Dahlia tubers can be started in March or April by potting them up under cover; in May or June, they can be planted outside. Dormant tubers can be planted outdoors in April or May if you don’t have enough room to start them indoors or in a greenhouse.

Can I keep dahlias planted over the winter?

Dahlia tubers cannot be kept in the ground over the winter unless you live in Zone 8 or higher. They will rot and turn into compost if you do. In fact, it is imperative that you remove them before the first heavy frost, and it is preferable if you can do it soon after the first light frost.

Dahlias should be kept in a chilly (but not freezing!) basement or heated garage in the dark. Also required is a storage container, such as a sizable plastic bin or a flat cardboard box.

Dahlias reappear each year, right?

Dahlias produced a colorful display through late summer and autumn, but it ends as soon as the first frosts appear. Dahlias can’t withstand frost, so as the temperature drops, the leaves and remaining blossoms crumple to the ground. But not everything is lost. If you give the underground tubers a little tender loving care, they won’t be harmed and will be able to perform again year after year.

Dahlia tubers are sometimes extracted, stored over the winter, and then replanted in the spring. Others in drier climates simply leave them where they are. What is the greatest way to guarantee a repeat performance the next year?

Basically, they typically survive the winter undamaged if your soil is well drained and frost does not penetrate too deeply. You can aid by mulching the area once the faded vegetation has been chopped back to the ground level with a thick layer of leaf mould, decomposed bark, or bracken. Dahlias are less likely to survive in the ground in damp conditions, thick clay soils, and in cold climates; therefore, it is usually advisable to lift them and store them in a frost-free location until the following spring.

Trim the stems to a few centimeters above ground if you choose to dig them up and store them. With a fork, delicately lift the tubers, being careful not to scratch them.

As much dirt as you can remove, ideally without washing them. However, if the soil is sticky, careful hosepipe washing may be required.

Then, if possible outside or in a well-ventilated shed or garage, let them dry for a few hours. Turn the tubers upside down so that the stem remnants are facing down when they are relatively dry, and then spread them out on dry newspaper so they can be left undisturbed until all of the extra moisture and sap has drained away. A place with no frost is necessary, as well as good ventilation. Conditions below freezing will always kill them.

Dahlia tubers were traditionally sprinkled with yellow sulfur to stave off fungus invasion. Many people use this on dahlia tubers as a prophylactic strategy even though it is advised as a plant nutrient and soil acidifier.

Some others simply spread the tubers in trays covered with fresh newspaper. Others spread the tubers out on wooden trays or even shallow cardboard boxes after loosely wrapping each one in a sheet of newspaper. Then, they must be kept in a dry, frost-free location with excellent air flow. Regularly inspect them and get rid of those that appear to be rotting because it will spread to the others.

Dahlia tubers can be planted directly into the ground where they will bloom in the middle of April. Avoid planting too early to prevent frost damage to the developing shoots.

As an alternative, you may start them in pots indoors and then plant them outside once they have grown.

While wind can harm their fleshy stems, dahlias prefer refuge from it and thrive best in an open, sunny location. Although they like plenty of organic materials around them, they prefer well-drained soil. The greatest results are ensured by a slow release fertilizer used early in the growing season; Vitax Q4 is perfect.