Are Dahlias Perennials? The Ultimate Guide to Planting and Care

Are Dahlia’s perennials? We all want to know, read on and learn about many of the details involved in growing dahlias.

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Welcome to Dahlia Gardening

Dahlias are flowering plants with tuberous roots native to the mountains of Mexico and Central America.

There are several thousands of different dahlia varieties that you can grow in your garden. The hardest part is picking your favorite ones. It’s like picking your favorite candy.

The plants range from 1″ to over 6 feet tall, and their blooms range from ” up to 18. Can you imagine a flower so big?

Are Dahlias Perennials?

If you are new to growing dahlias you will probably ask the question, are dahlias perennials or are they annuals? Well, the answer may surprise you!

This answer is dahlias can be either perennials or an annuals depending on your plant hardiness zone.

So how do you know? Let me explain.

Are Dahlias Perennials? Understanding the Dahlia Lifecycle and Your Hardiness Zone

Dahlias are considered tender perennials, which means their plant classification is determined by where you live.

These plants bloom from midsummer through fall.

Choosing The Right Dahlia Varieties for Your Garden

Depending on the Dahlia variety that you choose, there can be a wide range of flower sizes! Dinner Plate Dahlia flowers are the largest, and Pompon Dahlia flowers are the smallest – and there are several in between.

Types of Dahlias

There are too many to mention, but some of my favorite varieties are Dinnerplate Dahlias, Powder Puff Dahlias, Anemone Dahlias, White ball Dahlias, free flower type varieties of small decorative dahlias, and the sport variation dahlias.

Tips and Tricks for Choosing Dahlias for Your Garden

Where to Buy Your Dahlia Seeds and Tubers

There are several places to buy your tubers, but I am a bit partial and love the variety I can get

From Sarah’s Cottage Creations Flower Farm. Once a year, the farm has a dahlia tuber sale where you can purchase your favorite varieties of dahlias. This year the sale starts Saturday, January 21st. Yup, that is tomorrow!! And I cannot wait. 

You can click HERE and see the gorgeous dahlias that will be going on sale.

A Beginner’s Guide to Planting Perennial Dahlias

What Growing Conditions Do Dahlias Need?

Dahlias can be grown outside in most climates, but they prefer warmer weather. If you live in a cold environment, you must wait for the last frost to pass before planting.

It is best to grow dahlias in a moist well, drained sandy soil rich in organic matter, and a ph level of 6.0-7.5.

Dahlias are sun lovers and thrive with 7-8 hours of sunlight.

When to Plant Perennial Dahlias

The ideal time to plant your dahlias will depend on your climate.

Starting your tubers indoors or in a greenhouse is very common for an avid gardener and can be done up to 45 days before planting.

Dahlia seeds are also another way to grow dahlias. You can start your seeds in a greenhouse or indoors as well.

How to Plant Dahlias

Planting Dahlia Seeds

Use a seed tray and fill the tray with moist seed-starting soil

Using the end of a pencil, make a small hole in the ground, place your seeds in the hole, and gently cover the seeds with soil.

Moisten the soil and keep it moderately damp at 70 degrees Fahrenheit.

Using a greenhouse or covering over your seeds will help this process.

Germination should occur 7-12 days later.

Once the plants are large enough that their leaves are touching each other, it is time to replant them into a larger container. Again, I suggest a 3” pot or larger. Once the plants are large enough that their leaves are touching each other, it is time to replant them into a larger container. Again, I suggest a 3” pot or larger.

If you have grown your seeds indoors, you must harden them off. Hardening off is a process to acclimate them to the natural environment outside.

This process involves taking them outdoors for short periods and increasing that time each day.

Be sure to make sure the last frost has passed before you plant them in the ground.

You may find that the plants from seeds will take longer to bloom than planting tubers or small plants.

Planting Dahlia Tubers

Now that you know the answer to this question, “are dahlias perennials” let’s talk about their roots or tubers. In areas where Dahlias are considered perennials, you can leave the tubers in the ground all year. That would be zone eight and higher.

As I mentioned above, you must wait until the last frost has passed, and ideally, the soil temperature is 55 degrees or higher. In most areas, this occurs in Mid-April through May.

Prepare your soil to be moist and well-drained with a ph of 6.0-7.5. If you have no idea what the ph of your garden soil is, you can purchase a soil tester to check it and then amend your soil to get your dahlias off to a great start.

If your soil is very clay-like, you can add sand, vermiculite, and peat moss to make it drain well. Typically, you can find these soils at Home Depot and local nurseries.

“Dig a small hole approx. ” – 6” deep, sprinkle a handful of bonemeal in the hole and lay your tuber on its side in the hole.”Dig a small hole approx. 4” – 6” deep, sprinkle a handful of bonemeal in the hole and lay your tuber on its side in the hole.

Place your tuber in the ground with the eye of the tuber facing up and cover it with dirt.

Next, you need to sit back and wait….. for those sweet green leaves to make their way through the soil. Do not water the plants until the tubers have sprouted. (If you water early, it can cause the tubers to rot)

Once the plants have sprouted, they should get a deep watering 3 to 4 times a week. You can also use a drip system or a soaker hose for extended periods.

Caring for Your Dahlias: Tips for Growing Beautiful Blooms all Season Long

Watering and Fertilizing Dahlias

Feed your dahlias monthly during the blooming season with a fish emulsion mixture. (Read the directions on the bottle of fish emulsion).

It also important to water them well. Especially during hot and dry weather.

You should also use mulch around your plants top help retain soil moisture.

Staking and Supporting Dahlias and other Tall Perennials

Some dahlias can grow to a height of 6’ with a very heavy stalk, so you may need to stake your plants. Some dahlias can grow to a height of 6’ with a very heavy stalk, so you may need to stake your plants.

Typically, you will find that the plant will bloom more efficiently if it has proper support. Staking also aids in aeration, protects from wind damage, and more.

You can read up on staking your dahlias HERE. This article is full of great information.

Pinching Dahlias: How to Do it and Why it is Important

Pinching your Dahlias will help to grow a hardier plant and could help the plant to bloom longer.

You want to wait until the plant has reached a height of approximately 10-12” tall.”You want to wait until the plant has reached a height of approximately 10-12” tall.

Pinch off the newest sprout of leaves on the main stem. Doing this will encourage more lateral growth, which gives you a bushier plant.

Protecting Your Dahlias from Common Pests and Diseases

Unfortunately, small common pests include snails, slugs, earwigs, caterpillars, grasshoppers, thrips, and more.

These pests love to fill their bellies with dahlias.

Having healthy plants is your best defense. However, at times you need. Keep your beds clean and free of debris.

Where critters can hide out Early morning is the best time to inspect for bugs. You can often remove them with your fingers or use a mild insecticidal soap.

You can use a bug deterrent of choice, such as Bacillus thuringiensis, a natural bacterium.

You do not want to use pesticides that will hurt insects that are beneficial to your garden.

Occasionally dahlias can be suspectable to fungal disease. First, avoid fungal infection by planting your plants 18-24” apart, so they have proper aeration. If you happen to see a fungal disease starting, snip off the leaves or buds and then treat them appropriately. Occasionally dahlias can be suspectable to fungal disease. First, avoid fungal infection by planting your plants 18-24” apart, so they have proper aeration. If you happen to see a fungal disease starting, snip off the leaves or buds and then treat them appropriately. 

Deheading Your Dahlias

Deadhead spent blooms by cutting down to the main stem.

Harvesting Your Dahlias

Cut your flowers early in the day when it is cool.

Place the fresh-cut blooms in a glass of hot water (160-180 degrees) and let it.

Cool for an hour.

Replace the water in your vase daily.

Should You Overwinter Your Dahlias?

Only in zones eight and higher does the ground remain warm enough that the tubers do not freeze.

If you live in a colder hardiness zone, your tubers need to be dug up and stored in a warm area for the winter.

I have a few tips or digging and storing and overwintering.

How to Propagate Dahlias

Dividing Your Tubers

Once your plants have finished blooming and have died, back you want to cut the foliage off, leaving about a 3-4” stem sticking out of the ground. the foliage off, leaving about a 3-4” stem sticking out of the ground.

Using a pitchfork or a shovel, dig up the plant tubers, and shake off the access dirt.

Let dry in a cool area for a few days.

Place the tubers in a box of vermiculite or similar material and store them in an area that will remain at approximately 50 degrees or lower for the winter.

When you are ready to divide your tubers for the spring, be sure to cut each piece with an eye.

Allow each piece to dry for a few days before you plant them.

Growing Dahlias from Cuttings

Now that you know everything there is to know about Dahlias, I hope you grow some in your garden. They make the most beautiful cut flowers you will enjoy all summer.

And I promise, once my garden starts to blossom, I will share more with you.

More about me!