When will my Dahlias Bloom?

Jane Westoby
Apr 1, 2024
3 min read

Updated: Mar 6

When Will My Dahlias Bloom? How to Get Earlier Flowers

It’s all go on the dahlia front right now. This is the time of year I look forward to the most—potting up my tubers and watching them spring to life. If you’re wondering when your dahlias will bloom, the answer depends on several factors—but with the right approach, you can get them flowering as early as possible.

How Long Do Dahlias Take to Bloom?

On average, dahlias take around 90 days from planting to flowering. However, the exact timing varies depending on:

Variety – Some species naturally bloom earlier than others.
Light levels – The more warmth and sunlight, the quicker they grow.
Temperature – Cold, wet weather slows growth significantly.
Watering & nutrients – Too much or too little can delay blooms.
Taking cuttings – Removing early shoots can delay the mother plant’s first flowers, but those cuttings can bloom earlier than the original tuber.

If you want earlier blooms, the key is starting tubers indoors as soon as possible.

How to Get Dahlias Blooming Early

I grow dahlias on the south coast of England (Zone 9), where the climate is mild due to the sea, but much of southern England is Zone 8. To get a head start on the season, I bring my tubers indoors in February—yes, right into the house!

Step 1: Wake Up the Tubers

Leave tubers in their crates for 2 weeks in a warm indoor space.
This gentle heat encourages the formation of eyes (the growth points where shoots will emerge).

Step 2: Pot Up in Trays & Pots

After two weeks, pot them up with a little soil and lightly water—just enough to keep the compost damp, never wet.
If kept warm (on a heat mat or inside the house), they will sprout in a week.
In an unheated greenhouse or summerhouse, they’ll take a couple of weeks longer.

Avoid overwatering. Tubers sitting in wet soil will rot before they even get started.

Step 3: Managing Growth & Cuttings

Taking cuttings? Be aware this sets the mother plant back by around 4 weeks.
However, the cuttings themselves often bloom earlier than the original tuber, so it’s a trade-off.

Step 4: Keeping Dahlias Frost-Free

Dahlias cannot survive frost, so they need to be protected until the weather settles. They can be kept in:

A porch, shed, greenhouse, summerhouse, or even a kitchen windowsill.
A portable mini greenhouse works well—mine is on a trolley base with wheels so I can move it in and out depending on the weather.

Planting Out Dahlias

By late April, the risk of frost in my area is minimal, so I start thinking about planting out. However, I wait until plants are at least 15–20cm tall before moving them outside. Any smaller, and they are an easy target for slugs.

How to Plant Dahlias in the Ground

If you have heavy or wet soil, plant in raised beds or ensure good drainage.
Dig a hole, place the dahlia in, water well, and stake immediately.
If you haven’t already pinched out the growing tips, do so at this stage to encourage bushy plants with more blooms.

When to Expect Flowers

Dahlias start producing a steady stream of flowers from July onwards, with blooms peaking in August and September. As the days shorten and temperatures drop, they gradually slow down before being blackened by the first frost.

The Secret to More Blooms

Start tubers early indoors for a longer flowering season.
Pinch out early growth to encourage stronger, bushier plants.
Protect from slugs in the early stages.
Provide good drainage to prevent rot.

With the right care, dahlias will keep blooming until the first frost, filling your garden with colour, texture, and plenty of cut flowers for months on end.