Growing Dahlias: The Ultimate Guide to Gorgeous Blooms

I love growing dahlias because they give me so many beautiful flowers from summer until the first frost hits. These amazing plants are way easier to grow than most people think.

If you can grow tomatoes in your garden, you can successfully grow dahlias too.

The best part about dahlias is how many different colors and sizes you can choose from. I’ve grown tiny pom-pom dahlias and giant dinner-plate sized ones.

They all start the same way – with a tuber that looks kind of like a sweet potato. Once I planted my first few tubers, I was hooked.

Now I grow dozens of different types each year.

Key Takeaways

• Plant dahlia tubers in warm soil with good drainage and full sun for best results
• Care for dahlias by watering when rainfall is less than one inch per week and staking tall varieties
• Dig up tubers after frost to store over winter and multiply your dahlia collection for next year

Choosing the Right Dahlias for Your Garden

I’ve learned that picking the right dahlia types and healthy tubers makes all the difference. Your local weather and growing space will help guide your choices.

Popular Dahlia Varieties

I always tell new growers to start with reliable varieties that bloom a lot. Ball-type dahlias like Cornel are timeless classics with deep red colors that win awards.

For peachy colors, I can’t say enough good things about Clearview Peachy. This variety gives me long straight stems and tons of flowers all season long.

Isabel is another ball dahlia I grow every year. It has pretty lilac blooms with coral hints and keeps making flowers until frost hits.

My top picks for beginners:

• Cornel (deep red ball type)
• Clearview Peachy (peach ombre)
• Isabel (lilac with coral)
• Snoho Doris (peachy-pink)

I stay away from dinner plate dahlias in my first years. They look amazing but don’t make many blooms and need lots of care.

Selecting Healthy Dahlia Tubers

When I buy dahlia tubers, I look for firm ones without soft spots or mold. Good tubers are the roots of the dahlia plant that you put in the ground.

Healthy tubers feel solid and have visible eyes or growing points. I avoid any that feel squishy or smell bad.

What I check for:

• Firm texture (not soft or mushy)
• No dark spots or mold
• Clear growing eyes
• Good size (not tiny or huge)

I buy my tubers from trusted sellers who store them right. The American Dahlia Society has lists of good growers to buy from.

Spring is the best time to buy since tubers are fresh from winter storage. I plant mine after my last frost date.

Factors to Consider for Your Climate

My dahlias need different care based on where I live. Dahlias need full sun with at least 6-8 hours of direct sunlight daily.

In hot areas, I pick varieties that handle heat well. In cooler places, I choose ones that bloom early before frost comes.

Climate tips I follow:

• Hot climates: Choose heat-tolerant types
• Cool areas: Pick early blooming varieties
• Windy spots: Select shorter, sturdy stems
• Short seasons: Go with fast-growing kinds

I also think about my soil type. My dahlias want rich soil that drains well but stays a bit moist.

If I live where it freezes, I dig up my tubers each fall. In warm areas, I can leave them in the ground all year.

Planning and Preparing Your Dahlia Bed

Getting your dahlia bed ready is the most important step for growing amazing flowers. You need the right spot with good sun and soil that drains well.

Site Selection and Soil Preparation

I always tell my friends that dahlias are sun lovers. Your dahlias need at least 6 hours of direct sun each day.

More sun is even better! The soil needs to drain well.

Dahlias hate wet feet. If water sits on top of your soil after rain, you need to fix that first.

I like to add compost to my dahlia beds. This makes the soil rich and helps it drain better.

Mix in about 2-3 inches of compost before planting.

Key soil requirements:

• Well-draining soil
• Rich in organic matter
• pH between 6.0-7.0
• Not too wet or soggy

Test your soil before you plant. You can buy a simple test kit at the garden store.

If your soil is too clay-like, add sand and compost. I keep track of my soil prep in my garden journal.

Writing down what I add each year helps me remember what works best.

Raised Beds vs. Ground Planting

Growing dahlias in raised beds offers better growing conditions because you control the soil quality. The plant roots can breathe easier too.

I love raised beds for dahlias. You can fill them with the perfect soil mix.

You also get better drainage, which dahlias really need.

Raised bed benefits:

• Perfect soil control
• Better drainage
• Easier to weed
• Less bending over

Ground planting works fine if your soil drains well. It costs less money to start.

You just need to work harder to improve the existing soil. For raised beds, make them at least 8 inches deep.

Fill with a mix of compost, topsoil, and some sand. This gives your dahlias the best start.

If you plant in the ground, dig down about 12 inches. Mix in lots of compost.

Remove any rocks or roots you find.

How to Plant Dahlias: Step-by-Step

Getting your dahlias in the ground correctly sets you up for months of beautiful blooms. I’ll walk you through the best timing, proper tuber planting techniques, and alternative growing methods that work.

When to Plant Dahlias

I always wait until the soil warms up before I plant my dahlia tubers. The ground needs to be at least 60 degrees for the best results.

Timing by region:

• Cold areas: Late May to early June
• Warm areas: Mid to late April
• Hot areas: March to April

I check my local frost dates first. Plant dahlias after all danger of frost has passed to keep your tubers safe.

Cold soil makes tubers rot. You can start tubers indoors 4-6 weeks early if you want bigger plants.

Just use pots and move them outside when it’s warm enough.

Planting Dahlia Tubers

I start by picking a sunny spot with good drainage. Dahlias need at least 6 hours of direct sunlight each day.

Here’s how I plant each tuber:

1. Dig a hole 4-6 inches deep
2. Mix in compost or aged manure
3. Place the tuber on its side with the eye facing up
4. Cover with 4-6 inches of soil
5. Mark the spot but don’t water yet

The “eye” is the small bump that looks like a potato sprout. This is where your plant will grow from.

Spacing guide:

• Small dahlias: 12 inches apart
• Medium dahlias: 18 inches apart
• Large dahlias: 24-36 inches apart

I don’t water right after planting. Wet soil can make tubers rot before they start growing.

Wait until you see green shoots above ground.

Growing from Cuttings and Seed

I sometimes grow dahlias from cuttings when I want more of my favorite plants. Take 4-inch cuttings from healthy shoots in late spring.

For cuttings:

• Cut below a leaf joint
• Remove bottom leaves
• Dip in rooting powder
• Plant in potting mix
• Keep moist and warm

Growing from seed gives you totally new dahlia varieties. But the flowers won’t look like the parent plant.

Seed starting steps:

• Start seeds indoors 6-8 weeks before last frost
• Use seed starting mix
• Keep soil at 70-75 degrees
• Transplant after danger of frost passes

Most dahlia seeds make single flowers with open centers. They’re great for cutting gardens and attract lots of bees.

I prefer tubers because I know exactly what flowers I’ll get. But seeds are fun if you like surprises in your garden.

Dahlia Care and Maintenance

I’ve learned that proper watering, strong support, and watching for pests are the three main things my dahlias need to stay healthy all season long. Getting these basics right means I get way more blooms and stronger plants.

Watering and Fertilizing Dahlias

I water my dahlias deeply once a week rather than giving them little sips every day. This helps their roots grow strong and deep.

When I water lightly in pots, I use about ¼ to ½ cup of water weekly. For garden dahlias, I soak the soil around each plant until water runs off.

I always water early morning or evening. This gives plants time to drink before the hot sun hits them.

My Feeding Schedule:

• Weeks 1-3: No fertilizer needed
• Weeks 4-16: High potash feed every two weeks
• Late season: Stop feeding 4 weeks before first frost

I feed my dahlias with tomato fertilizer every other week once they start blooming. Tomato food has the right mix of nutrients to keep flowers coming.

The soil should feel damp but not soggy. I stick my finger 2 inches down to check moisture levels.

Staking and Supporting Plants

I put stakes in the ground right when I plant my dahlia tubers. Waiting until later can damage the roots.

Support Options I Use:

• Single stake: Works for plants under 3 feet tall
• Bamboo canes: I place 4 canes around larger dahlias
• Metal rings: Good for medium-sized varieties

Most dahlia varieties need staking because they grow fast and can flop over. I learned this the hard way when wind knocked down my unsupported plants.

I tie stems loosely with soft garden twine every 2-3 weeks as they grow. The ties should be snug but not tight enough to cut into the stem.

For really tall dahlias, I use 6-foot stakes pushed 18 inches deep. This gives them solid support even in storms.

Pest and Disease Management

Slugs and snails are my biggest dahlia enemies. They love eating the soft new shoots and can destroy young plants overnight.

I scatter slug pellets around my plants and check for damage every morning. Copper rings around each plant also work well to keep slugs away.

Common Pests I Watch For:

• Slugs/snails: Eat leaves and stems
• Earwigs: Damage buds and flowers
• Aphids: Cluster on new growth

I make earwig traps by putting straw-filled pots on garden stakes. The earwigs hide in the pots during the day, then I dump them out.

Spider mites show up during hot, dry weather. I spray the undersides of leaves with water to wash them off.

For disease prevention, I space my dahlias properly so air can flow between plants. Crowded dahlias get fungal problems more often.

Multiplying and Storing Dahlia Tubers

I love how one dahlia can turn into many plants for next year. A single dahlia tuber can produce 3-7 new tubers in just one growing season, and proper storage keeps them safe through winter.

How to Lift and Divide Tubers

I wait until after the first hard frost kills my dahlia plants. Then I cut the stems down to about 6 inches tall.

When to dig:

• After frost blackens the leaves
• Before the ground freezes hard
• About 2 weeks after cutting stems back

I use a spade shovel to dig around each plant. I go about 12 inches out from the stem to avoid cutting the tubers.

Dahlia tubers spread out like an octopus underground. After I lift the clump, I brush off the dirt gently.

I don’t wash them with water because wet tubers rot easily.

To divide tubers:

• Look for the “eyes” – small bumps where new growth starts
• Each piece needs at least one eye to grow
• Cut with a sharp, clean knife
• Let cut pieces dry for a day before storing

Some varieties give me lots of tubers. Others only make a few new ones each year.

Overwintering Dahlia Tubers

Dahlia tubers need to stay between 40-45 degrees through winter. They also need humidity so they don’t dry out and die.

I store mine in my basement or garage. Cool, dark places work best for keeping tubers healthy.

My storage method:

• Put tubers in boxes with peat moss or wood shavings
• Pine shavings help keep humidity at 70-80%
• Label each variety clearly
• Check them once a month

I throw away any tubers that feel soft or look moldy. Good tubers feel firm like a potato.

Storage problems to watch for:

• Too dry: Tubers shrivel up
• Too wet: Tubers get soft and rot
• Too warm: Tubers start growing too early
• Too cold: Freezing kills them

Creative Ways to Grow Dahlias

Growing dahlias doesn’t mean you need a big yard or perfect soil. I’ve found that grow bags, pots, and small spaces can work just as well as fancy garden beds.

Growing Dahlias in Grow Bags

I love using grow bags for my dahlias. They’re cheap and easy to move around my yard.

Best Grow Bag Sizes:

• 20-gallon bags for big dahlia types
• 15-gallon bags for medium dahlias
• 10-gallon bags for smaller types

I fill my bags with half potting soil and half compost. This mix keeps my dahlias happy all season long.

Grow bags dry out fast in hot weather. I water mine every day when it’s sunny.

The fabric sides help air get to the roots too.

My Grow Bag Tips:

• Put bags on wheels so you can move them
• Use saucers under bags to catch water
• Add more soil as it settles down

I can fit three grow bags where one big planter used to go. This lets me try more dahlia colors each year.

Container Gardening with Dahlias

Growing dahlias in containers lets me grow them on my deck and porch. I use pots that are at least 12 inches deep and 16 inches wide.

My wooden barrels work best for dahlias. They hold more soil and drain well.

I can fit two or three tubers in my biggest pots.

Container Must-Haves:

• Good drainage holes in the bottom
• Fresh potting mix each spring
• Daily watering in summer

I replace all my pot soil every year. Old soil doesn’t feed dahlias well.

I mix new potting soil with compost before planting. Big pots heat up faster than garden soil.

This means my container dahlias bloom sooner than the ones my neighbor plants in her yard.

I stake tall dahlias right when I plant them. It’s easier than trying to add stakes later when roots are big.

Dahlias in Urban Spaces

City gardening means getting creative with small spaces. I grow dahlias on my fire escape, roof, and even in window boxes.

Urban Growing Spots:

• Balconies with morning sun
• Flat rooftops with wind protection
• Shared courtyard gardens
• Community garden plots

Wind is the biggest problem in the city. I use shorter dahlia types or put up screens to protect taller ones.

My apartment building has a shared roof space. I bring my pots up there each spring.

The extra sun makes my dahlias bloom like crazy. City air can be dirty, so I wash my dahlia leaves with a hose once a week.

Clean leaves grow better flowers.

I pick dahlia types that don’t get too tall. The shorter ones handle city wind much better than the giant ones.

My Urban Favorites:

• Border dahlias under 2 feet tall
• Dwarf types for small pots
• Ball dahlias that don’t need stakes

Frequently Asked Questions

I get lots of questions about growing these amazing flowers. Let me share what I’ve learned about getting blooms, planting tubers, and caring for dahlias.

How do you get dahlias to bloom beautifully?

I always make sure my dahlias get at least 6 hours of sun each day. Full sun locations with well-drained soil work best for me.

I pinch my plants when they’re about 8 inches tall. Using fingers or scissors to remove the center shoot above the third set of leaves helps me get more flowers.

I cut off old flowers right away. This makes my plants keep making new blooms all summer long.

I feed my dahlias every few weeks. I use plant food that’s low in nitrogen so they make flowers instead of just leaves.

What’s the best way to plant dahlia tubers?

I wait until my soil feels warm to touch. Dahlias don’t like cool soil and won’t grow well if it’s too cold.

I dig holes about 6 inches deep. I place the tuber with the eye part facing up.

I cover them with soil and water gently. I don’t soak them because wet tubers can rot.

I space my big dahlias about 2 feet apart. Smaller ones can be closer together.

Can you give me tips for starting dahlias from seed?

I start my dahlia seeds inside about 6 to 8 weeks before the last frost. This gives them time to grow strong.

I plant the seeds in small pots with good soil. I keep them warm and give them lots of light.

I water them just enough to keep the soil damp. Too much water kills the baby plants.

When they get bigger and frost is done, I move them outside. I wait a week or two to let them get used to being outside.

Seeds take longer to bloom than tubers. But I get to try new types this way.

I want to grow dahlias indoors, how should I start?

I pick a sunny window that gets light all day. If I don’t have one, I use grow lights.

I keep my indoor dahlias between 65 and 70 degrees. They don’t like it too hot or too cold.

I use big pots with holes in the bottom. Good soil that drains well is key.

I water when the top of the soil feels dry. Indoor air can make them thirsty.

I turn the pots every few days so all sides get light. This keeps them growing straight.

What should I know about growing dahlias in pots?

I use big pots because dahlias have big roots. Small pots don’t give them enough room.

I pick shorter dahlia types for pots. The tall ones can tip over in windy weather.

I check my pots every day in summer. Container dahlias need more water than ones in the ground.

I feed them more often too. The plant food washes out faster in pots.

I can move my pots to follow the sun. This helps them get the light they need.

Are dahlias annual or perennial, and how do I care for them?

Dahlias are plants that come back each year in warm places. But where I live, frost kills them in winter.

I dig up my tubers after the first frost turns the leaves black. I cut the stems down to about 6 inches first.

I store my tubers in a cool, dark place and check them weekly to make sure they’re not too dry or getting moldy.

I keep them in barely damp peat or sand all winter. Come spring, I plant them again.

Some people in warm areas can leave them in the ground. I add thick mulch if I try this.