Dahlias are some of the highest-producing cut flowers and ornamental garden plants from the daisy family that you can grow at home.
Unlike many other flowers, dahlias do not require a lot of maintenance, and they can produce spectacular blooms.
There are so many species and hybrids of dahlias that they come in various hues and sizes.
When to plant dahlias? The best time to grow dahlias varies from climate to climate. In tropical and dry regions, it is always best to plant in the fall. In super cold areas, however, the best time to plant is after each year’s final frost.
The following sections will discuss the pertinent details about growing dahlias in different climates and how to grow them from seeds and tubers.
Planting Dahlias in Different Climates
The dahlia flower is native to the Andes Mountains of South America, where people mostly grow it as a perennial.
However, some growers in cold regions grow them as annual plants with a thick layer of protective mulch.
While some dahlias have soft, herbaceous stems, others have stems that lignify during and resprout after the cold season.
Dahlias like cool climates, but they will grow in the tropics as long as they are kept cool and properly cared for, especially during the hot mid summers.
Ideal heat-tolerant dahlia varieties for planting in the tropics include Juanita, Prince Noir, and Kidd’s Climax.
When planting in a tropical region, always choose the right location.
Dahlias need the full sun to grow even in hot climates, but they will need sun-shading for the afternoon heat.
To survive in the hot tropics, it is always best to plant dahlias in slightly acidic, well drained soil.
Till the soil at least ten inches deep, add compost, peat moss, rotted manure, and a balanced fertilizer.
Three pounds of an 8-8-8 or 10-10-10 per a hundred square feet should do the trick.
The only tip to remember when planting dahlias in a dry climate is to water regularly.
Add moisture to the dry soil at least every other day, just enough to give the dahlias water to grow.
Temperate and Polar Climates
If you’re planting dahlias in a climate where extreme cold is unavoidable, you will have two care options.
The first is to dig them up and store them during the cold months, and the second is to keep them warm enough in the ground.
During the freezing winters, digging them up and properly storing them will keep the dahlia flowers coming every year.
Leaving them in the ground during freezing temperatures turns them into an unproductive clump of tubers.
If you do not want to go through the hassle of digging them up and storing them, you can treat the dahlias as annuals and purchase a new set of plants each year.
But if your area does not receive harsh cold months, the dahlias may survive winter without digging.
Going with the second option requires a thick layer of mulch to keep the tubers warm in the ground.
Take note of your area’s frost dates and wait at least a week after a freeze from the fall when your dahlia stalks have completely dried.
Cut the stalks down to the ground and cover the area with a foot-deep mulching layer of grass clippings, compost, straw, or leaves.
When springtime comes, remove the mulch and wait until the soil has warmed before you dig the tubers out.
Dry the tubers for at least four days and replant them when the right planting time comes.
When speaking of planting dahlias in a continental climate, the most diagnostic condition to consider is a large temperature range.
Areas with a continental climate tend to have moderate year-round precipitation, which means the soil does not dry totally.
With a continental climate, summer weather is more stable, which means your dahlias would do well with the same practices as in the tropics.
However, the cold, winter months in continental regions are quite unstable.
Your dahlia tubers will do better dug up and properly stored during the chilly months.
What is the best month to plant dahlias?
The best months to plant dahlias in the tropics and dry climates is in the fall when it is not too hot and the soil stores enough moisture from natural precipitation.
In temperate and Polar Regions, plant the tubers outdoors after the last frost dates of every year when the soil has warmed enough.
When planting dahlias in continental regions, consider planting dahlia tubers around warm, stable summers rather than around erratic freezing temperatures.
Collecting Dahlias Seeds
Growing dahlias from seeds entails collecting the seeds from dried dahlia flowers.
As soon as the flowers dry out, the petals become papery thin.
Attached to each dried-out petal is a dark seed.
To collect the seeds, pluck out the petals one by one and separate the seeds from each petal base.
With every dried dahlia flower, you will be able to collect around 50 seeds.
Seed-sown dahlias tend to grow as single-flower plants that are excellent for flower beds and garden borders.
How to Plant Dahlias Seeds
You can grow dahlias from seeds sown early indoors before the final frost, or you can wait until after the frost so you can plant the seeds directly in the ground.
Sowing Dahlia Seeds Indoors
When sowing seeds indoors, you can start eight weeks before the last frost.
Step 1. Prepare your indoor planting kit.
You will need seed-starting soil and drainable pots or plant boxes.
Step 2. Plant the seeds.
Sow the dahlia seeds in the soil to a depth of a quarter of an inch.
Step 3. Keep the soil moist and at the right temperature.
Have a planting thermometer handy and check that the soil temperature is between 70 and 75 degrees Fahrenheit.
Keep the soil moist but never overwater.
Step 4. Wait for seedling emergence.
The seedlings will start to emerge in about 14 to 20 days.
Step 5. Give it sunlight.
As soon as they emerge from the soil, position the plant boxes on a sunlit windowsill.
Step 6. Feed with fertilizer.
Seedlings do not need a lot of fertilizer, so feed them only when they are about three or four weeks old.
Step 7. Transplant to the ground after the final frost.
Transplanting involves hardening off your seedlings.
Once you bring them out after the final frost, be sure that they are still protected from extreme sunlight and strong winds.
Sowing Directly in the Ground
Step 1. Wait for the final frost.
Let the final frost pass before sowing directly in outdoor plots.
Step 2. Select appropriate planting location.
Choose an area where there are rich and moist organic soil and full sun.
However, in hot climates, the dahlias should have enough shading during the hottest hours of the day.
Step 3. Till the soil and amend it with organic matter.
Soften the planting bed with a rake or a planting shovel, and mix in some compost.
Step 4. Plant the seeds.
Sow the seeds to a depth of a quarter of an inch, which should be enough for germination.
Step 5. Wait for seedling emergence and thin the plants.
As soon as the seedlings emerge within 20 days and the seedlings are an inch high, thin the plants to 25 inches apart.
How to Grow Dahlias from Tubers
Although you can sow dahlias from seeds, they are more commonly grown from tubers.
Tuberous dahlias have larger flowers than seed-sown dahlias, and they typically do not grow from the seeds.
Let’s say you purchased or received some dahlia tubers.
The following steps outline the correct way to plant them.
Step 1. Choose the proper planting time.
The proper planting time for dahlia tubers is when the soil is around 60 degrees Fahrenheit.
Step 2. Choose the correct location.
Next to enough moisture and rich organic material, sunlight is always important to produce more dahlia blooms.
Step 3. Till the soil and add organic material.
Prepare the planting bed by turning eight inches of soil and adding in compost.
Step 4. Make holes in the soil six inches deep and wide enough to accommodate a tuber laid on its side.
Put whole tubers into each hole and do not cut them into smaller pieces.
Step 5. Cover with a thin layer of soil.
Use around two inches of soil covering for each tuber, and add soil only when the plants grow.
How to Water Dahlias
An appropriate level of moisture in the soil is paramount to the successful growth of dahlias.
Keep in mind that overwatering can cause the tubers to rot, which is why watering methods should also vary depending on your area’s climate conditions.
Use the following procedure for watering your freshly planted dahlia tubers.
Step 1. Do not water unless you plant on soil in a dry climate.
Step 2. Wait for the first sprouts to emerge before watering.
Step 3. Water the area two to three times weekly.
Using soaker hoses should do the trick.
Wet dahlia stalks and foliage are prone to diseases if they get wet regularly.
It is always better to soak the soil beneath the surface than to use a sprinkler to water your dahlias.
Step 4. Soak the soil up to six inches from the ground surface.
How long do dahlias take to grow?
For most dahlia varieties, it takes about eight weeks between tuber planting and flower blossoming.
Medium-sized dahlias bloom around ten to twelve weeks, while the large dinner plate dahlias will take a bit longer.
You can promote more blooms on your dahlias by pinching out the center growing stalk right above the fifth full set of leaves when the plants are about two feet tall.
In summary, the best practice is to plant dahlias when the soil reaches around 60 degrees Fahrenheit.
It is safe to plant the tubers in late March or early in April in the southern states.
In the Central US, April is also a good month to plant dahlias.
When growing in the Northwest, secure the garden plots early in May, but wait a little longer for areas in the far north.
Remember that dahlias grow and bloom best in a well-drained sunny site.
Don’t be worried if your garden opens to the woods, as dahlias are somewhat deer resistant plants.