When and How to Plant Dahlias: A Guide for Beginners

When and How to Plant Dahlias: A Guide for Beginners

Planting dahlias is a popular activity for gardeners all across America. These beautiful flowering plants, known for their vibrant colors and variety of shapes, can be divided into three main groups: the dinnerplate, the decorative, and the smaller pompon types. One of the most well-known dahlia varieties is the “Kathleen Thompson”, which has white blooms and grows tall.

If you are new to gardening or have never planted dahlias before, you may have some questions. When should you plant them? Where is the best place to plant them? How deep should you plant them? In this guide, we will answer these frequently asked questions and provide you with a step-by-step guide to successfully planting dahlias.

Dahlias are tender plants, so it is important to wait until after the risk of frost has passed before planting them outdoors. If you want to get a head start, you can start dahlias indoors by sprouting the tubers in pots a few weeks before the last frost date. This will give them a boost and allow you to transplant more mature plants into the garden.

When choosing a location for your dahlias, look for a spot that receives plenty of sunlight. Dahlias thrive in warm temperatures, so choose an area that stays above 60 degrees Fahrenheit. The soil should be well-draining and rich in organic materials. If your soil is heavy or clay-like, you may need to amend it with compost or other organic matter to improve drainage.

Before planting, prepare the soil by loosening it with a garden fork or tiller. Dig a hole that is wide and deep enough to accommodate the tuber. The general rule of thumb is to plant the tuber two times deeper than its width. If the tuber is 2 inches in diameter, plant it 4 inches deep. If the tuber is 3 inches in diameter, plant it 6 inches deep, and so on.

When planting, make sure the tuber is placed with the “head” facing up. The head is the fleshy part of the tuber where the sprouts will emerge. If you are planting multiple tubers, space them at least 2 feet apart to allow for adequate growth. If you are planting taller varieties, consider staking them to provide support as they grow.

After planting, water the tubers thoroughly to settle the soil. Throughout the growing season, be sure to keep the soil consistently moist, but not waterlogged. Dahlias are heavy feeders and will benefit from regular applications of liquid fertilizer.

When the first frost hits in the fall, it is time to prepare your dahlias for winter. Cut back the leaves to about 4-6 inches above the ground and carefully dig up the tubers. Allow them to dry in a cool, dark place for a few days before storing them for the winter. Some gardeners prefer to divide the tubers during this time, making it easier to plant them the following year.

So there you have it – a complete guide to planting dahlias. With their stunning colors and variety of types, dahlias are sure to wow any gardener. Whether you are a seasoned dahlia grower or just getting started, follow these tips and you’ll be able to enjoy beautiful blooms year after year.


Dahlias are beautiful flowering plants that are known for their showy blooms and variety of colors. They belong to the genus Dahlia, which includes more than 40 different species. Dahlias are popular among both experienced and novice gardeners due to their easy cultivation and stunning appearance.

When it comes to planting dahlias, timing is essential. They should be planted in late spring or early summer, preferably when the threat of frost has passed. Dahlia tubers should be planted about 6-8 inches deep in the ground. Make sure to choose a sunny spot with well-drained soil for optimum growth.

Before planting, it’s important to prepare the soil properly. Start by loosening it with a garden fork or shovel. Add compost or organic matter to improve drainage and provide essential nutrients. Dahlias require plenty of food to thrive, so fertilize the soil before planting with a balanced slow-release fertilizer.

If you’re growing dahlias from tubers, soak them in warm water for about 2 hours before planting. This will help them sprout faster and establish better. If you’re using potted dahlias, you can skip this step. However, make sure to gently loosen the roots of the plant before planting to encourage healthy growth.

When planting dahlias, spacing is crucial. They should be planted 1-2 feet apart to allow enough room for the plants to grow and spread. Place a stake or support for each dahlia plant to prevent it from falling over when it reaches its full height.

After planting, water the dahlias thoroughly. They require regular watering, especially during dry periods. However, be careful not to overwater them as it can lead to root rot. Mulching around the plants can help retain moisture and suppress weeds.

Dahlias are tuberous plants, meaning they have underground storage structures similar to bulbs. To encourage more blooms and healthier plants, it’s recommended to divide and replant dahlias every 3-4 years. This can be done in late winter or early spring before new growth appears.

Dahlia foliage, including the flowers, is quite sensitive to frost. If you live in an area with harsh winters, it’s important to dig up and store the dahlia tubers before the first frost. Cut back the foliage to about 4-6 inches above the ground and carefully lift the tubers. Clean off any excess soil and let them dry for a few days. Then, store them in a cool, dark, and dry place until it’s time to plant them again in the spring.

Overall, dahlias are versatile, beautiful plants that can add color and charm to any garden. By following the proper planting and care instructions, you’ll be able to enjoy their stunning blooms year after year.

Planting Dahlias When Where and How Deep

Dahlias are popular garden flowers that bloom from late spring to early fall. If you want to enjoy their showy and vibrant blossoms, it’s important to know when, where, and how deep to plant them.

When to Plant Dahlias:

Dahlias are sensitive to frost, so wait until all danger of frost has passed before planting them. In the United States, this is usually in late spring or early summer. Planting them too early can result in the tubers rotting in the cold, damp soil. Dahlias need warm soil and nights that are consistently above 50°F (10°C) to thrive.

Where to Plant Dahlias:

Dahlias love sunlight, so choose a sunny spot in your garden. Ideally, they should receive at least 6 hours of direct sunlight each day. The soil should also be well-draining to prevent waterlogged roots, which can lead to root rot.

How Deep to Plant Dahlias:

Dahlia tubers should be planted about 4-6 inches (10-15 cm) deep. Dig a hole deep enough to accommodate the tuber and its roots, and place the tuber with the eye facing up. The eye is a small, fleshy bud that will sprout a stem and leaves. If you’re unsure which end is the eye, don’t worry – the tuber will usually sprout from whichever end is facing up.

A Step-by-Step Guide for Planting Dahlias:

1. In late spring or early summer, choose a sunny spot in your garden with well-draining soil.
2. Dig a hole that is 4-6 inches (10-15 cm) deep.
3. Place the tuber in the hole with the eye facing up. If you’re unsure, place the tuber horizontally – it will still sprout.
4. Backfill the hole, covering the tuber with soil. Leave about 1 inch (2.5 cm) of the tuber above the soil.
5. Water the area thoroughly to settle the soil and promote root growth.
6. Apply a layer of mulch around the plant to help retain moisture and suppress weed growth.
7. As the plant grows, provide support with stakes or a cage to prevent the stems from bending or breaking.

After planting your dahlias, you’ll need to take care of them to ensure healthy growth and abundant flowering. This includes regular watering, fertilizing with a balanced liquid fertilizer, and removing any dead or damaged leaves.

Remember, dahlias are not winter hardy, so if you live in a region with freezing winters, you’ll need to dig up and store the tubers in a cool, dry place for the winter. This will protect them from freezing temperatures and allow them to be planted again next year.

If you follow these planting and care instructions, you’ll be rewarded with beautiful dahlias that will brighten up your garden and attract bees and butterflies!

How to Plant Dahlia Tubers

Planting dahlia tubers is a straightforward process that can yield beautiful blooms in your garden. Here’s a step-by-step guide to help you get started:

  1. Choose a frost-free area: Dahlias thrive in areas with plenty of sunlight, so choose a location that receives at least six hours of sunlight per day.
  2. Prepare the soil: Before planting, prepare the soil by digging a hole that is approximately twice as wide and deep as the dahlia tuber. This will give the roots plenty of room to grow.
  3. Soak the tuber: If the dahlia tuber is dry, you can soak it in water for a few hours before planting. This will help rehydrate the tuber and promote faster growth.
  4. Plant the tuber: Place the dahlia tuber in the hole, with the eyes facing up. The eyes are small points on the tuber where new growth will emerge.
  5. Cover with soil: Fill the hole with soil, covering the tuber completely. Press the soil down gently to ensure good contact between the tuber and the soil.
  6. Protect from frost: If there is a risk of frost, cover the newly planted dahlia tuber with a layer of mulch or straw to protect it.
  7. Water regularly: Keep the soil consistently moist but not waterlogged. Water the dahlia regularly, especially during dry spells.
  8. Support the plant: As the dahlia grows, it may need support to prevent the stems from bending or breaking. Use stakes or a trellis to support the plant as needed.
  9. Prune and pinch: To encourage bushier growth and more flowers, pinch off the top few inches of the plant when it reaches a height of about 12 inches. This will encourage the plant to branch out and produce more blooms.
  10. Wait for blooms: It may take a few months for the dahlia to bloom, but when it does, you’ll be rewarded with beautiful flowers in a variety of colors and shapes.
  11. Store tubers for winter: After the first frost, when the foliage has died back, dig up the dahlia tubers, remove the excess soil, and let them dry for a day or two. Store the tubers in a cool, dry place over winter.
  12. Divide and multiply: Dahlias can be divided to create new plants. In early spring, you can divide the tubers by cutting them into pieces, making sure each piece has at least one eye. Plant the divided tubers as you would with the original tuber.

Planting dahlias is a rewarding experience for gardeners of all levels, from beginner to expert. Follow these instructions, and you’ll be well on your way to enjoying the beauty of dahlias in your own garden.

✿ Read More About Flowers.

Dr Heidi Parkes

By Dr Heidi Parkes

Senior Information Extension Officer QLD Dept of Agriculture & Fisheries.