When you want a gorgeous bouquet of cut flowers, including dahlias is a must-have. These brilliant, bright, and colorful flowers will wow anyone who passes by your garden. Let’s find out when to plant dahlia tubers so you can have these marvelous beauties in your very own garden.
When to plant dahlia tubers: Those that want a garden full of lush blooms will do well with dahlias. Grown from tubers, these need to be in the ground in late spring. Wait until the ground temperature is at least 60 degrees Fahrenheit or else it will be too cold. The tubers should remain dry until the first shoots break through the soil, which happens around eight weeks after planting. Dahlias bloom in late summer, which is usually late August to September. If you live in a temperate climate, you can keep the tubers in the ground through winter. However, if you live in an area with very cold winters, you will need to dig up the tubers in the fall, store them properly in the winter, and then plant them again in the spring.
Planting Dahlia Tubers in Different Climates
Even though dahlias are considered a cool-climate plant because they need a period of dormancy, you can still try to grow them in a tropical climate. You will have to shift your planting time and care for the tubers during the hot summers.
Dahlias need sun and warmth to grow. A dry climate might be ok, as long as the nights are not too cold. You will also need to add your own watering to the flowers.
A temperate climate is great for dahlias. The mild winters mean there is a better possibility of you being able to keep the tubers in the ground over the winter.
The sun and heat in a continental climate are perfect for dahlias. However, the cold winters mean you will almost definitely need to remove the tubers from the ground and then re-plant them in the spring.
It is far too cold in a polar climate for dahlias to grow.
Choosing Dahlia Tubers
When it comes to choosing dahlia tuber varieties, the options can be rather overwhelming. There are so many colors and sizes to choose from, and if you are like most people, you want them all.
Size and color, however, are the best places to start. Think about if you want smaller bunches of blooms or giant-sized ones. Then, think about the color scheme you want and which colors go best together.
These dahlia plants grow to be about 4 feet tall and their long stems make them perfect for bouquets. Expect a deep red color from this variety.
With a soft, lavender color to them, you will love the subtle beauty of this variety. They have nice, strong stems that are pretty tall.
If you are looking for a soft, peachy hue, then this variety is perfect. With ball-shaped blooms that are about 4 inches in diameter, they are a really nice size.
While it is not a common variety, if you come across this option, you will be impressed by the buttercream center that is enveloped by a series of lovely white petals. This is a great variety for weddings or other celebrations.
How to Plant Dahlia Tubers
As much as we all love dahlias, this is a flower that can’t go into the ground too early. Don’t worry, though, as they don’t bloom until late summer so waiting a bit to plant them won’t disrupt their growing season.
Aim to plant your dahlia tubers in late spring. The ground temperature outside needs to consistently be above 60 degrees Fahrenheit for these flowers.
If you’re itching to get started, and you have smaller, dwarf varieties, you can start the tubers out in containers inside, about a month before planting.
Dahlias love the sun. They love warmth and summer conditions, so make sure there is nothing to obstruct these flowers as they grow.
Prepare the soil
For dahlias, you want the soil to be quite rich in nutrients and able to drain well. They prefer slightly acidic soil, so aim for a pH level around 6.5 to 7.0.
Have a look at your soil and see if you need to amend it. Heavier, clay-based soil will benefit from the addition of sand or aged manure.
Decide on neighbors
While some gardeners may want a huge section devoted to their dahlias, others may want a variety of flowers. This will determine where and how you plant your dahlias.
If you have a large section of dahlias, it’s best to leave them alone and not plant other types of flowers. This will allow you to properly stake larger varieties and monitor their progress so you can regularly cut the blooms.
If you have small or medium-sized dahlias, they are finely mixed in with other summer-blooming flowers. You can also add a row of dahlias to your vegetable garden as the large blooms will help attract important pollinators.
When you dig your hole, you can add a bit of bonemeal to the bottom. However, you should avoid fertilizer at this point.
Plenty of space
Unlike flower bulbs which are more compact, dahlia tubers can be a bit larger, depending on the variety. It’s important to dig a hole that is deep and wide enough to accommodate the size.
Larger dahlias should be spaced about 3 feet apart while smaller dahlias can be spaced 1 or 2 feet apart. If you have smaller, bushier dahlias, you can use them as a hedge.
If you have varieties that are very large, make sure you include stakes near them from an early start. This will help support the tall stems so that they don’t fall over.
How to Water Dahlia Tubers
Unlike other plants, which require watering immediately after planting, dahlia tubers are very susceptible to rot. You want to wait until the first shoots break through the soil before you start to water them.
Once your dahlias start to grow, you want to water two or three times a week and make sure that the water goes deep into the soil to penetrate the tubers.
If you have heavy rainfall, check on your dahlias, especially if they are in the flowering state. Large blooms can get knocked over with rain or wind, so try to provide support before a storm.
How to Grow Dahlia Tubers
A basic fertilizer, such as 5-10-10 can be used for dahlias. You want it to be low in nitrogen because too much can cause large foliage but small blooms.
Fertilize the soil after the dahlias emerge from the soil. Then, aim to fertilize every three to four weeks, right through the growing season.
Even though mulching can help prevent weeds from popping up, dahlias don’t actually like a lot of bark mulch. The extra layer means the roots don’t get the warmth from the sun, which they prefer.
Slugs are particularly drawn to dahlias, so avoid placing bark mulch as this can attract them. You can use eggshells to deter slugs or organic solutions from your gardening store.
Mites are also an issue. If you have had mites in the past, be proactive and use an organic spray from July to September.
Unfortunately, deer love dahlias. In order to prevent these massive eaters from destroying your hard work, use a mesh fence around your flowers.
Dahlias are a perennial but their tubers can only withstand so much cold over the winter. If you live in plant hardiness zones 8 to 11, you can overwinter them in the garden. You may also have some luck with zones 6 and 7.
If you have very cold winters, you will want to remove the tubers from the ground and store them during the winter. Then, you can plant them again the following spring.
After the blooms are finished, you can leave the foliage as this will help store nutrients inside the tubers. Once the first frost hits, the foliage will naturally die back.
If you live in a warmer area, cut the foliage back at this point and cover it with mulch to insulate the bulbs. Those in colder areas will do well to store their tubers in a dry, cool place during the winter.
How long do dahlia tubers take to grow?
Dahlia tubers should be planted in late spring, around May. After eight weeks, they will start to send shoots up through the soil.
Dahlias will then blossom in late summer, usually in August and September. If you cut dahlias for a bouquet, the plant will then produce more blooms, for a continual display of beauty.
Dahlias are simply wonderful to behold. Their bright, bold blooms are perfect as cut flowers. Plant your tubers in late spring, after the soil has really started to warm up, and you will be rewarded with gorgeous flowers in late summer.