The Dahlia Nerd Planting Guide

Everything you need to know to get your dahlias off to the best possible start.

There’s nothing quite like planting a dahlia and watching it grow into a beautiful, productive plant. A little preparation before planting can make a huge difference to how your dahlias perform throughout the season.

So, let’s get planting! 🌸

 

 Soil Preparation

 

Dahlias love rich, fertile, well-draining soil.

Before planting, prepare your soil by loosening it well and adding plenty of good-quality compost or organic matter.

Before planting:

● Break up compacted soil and remove weeds.

● Add well-rotted compost or quality organic matter.

● Make sure the soil drains well—dahlias don’t like sitting in constantly wet soil.

● Add a suitable fertiliser if required.

● Give the bed a good soak before planting if the soil is particularly dry.

Dahlia Nerd tip: Don’t plant into cold, waterlogged soil just because the calendar says it’s time. Warm soil will get your dahlias growing much faster.

☀️  Best Time to Plant

Dahlias are warm-season plants and don’t enjoy cold soil or frost.

The best time to plant is when the danger of significant frost has passed and your soil is beginning to warm up. November/December is a good time.

Don’t rush your planting.

Waiting for warmer soil can mean your dahlias establish much faster than planting too early into cold conditions.

If you’re growing in an area with late frosts, you may need to wait longer—or provide protection for your young plants.

Dahlia Nerd tip: If you’re impatient to get started, that’s completely understandable. We’re Dahlia Nerds after all! 🤓 But warm soil beats an early planting date every time.

How Deep to plant I Plant

 

Plant your dahlia tuber with the crown or eyes facing upwards.

As a general guide, plant the tuber so the crown is approximately 10-15 cm below the soil surface.

Once planted, cover the tuber with soil and water it in lightly.

 

How Far Apart 

Spacing depends on the variety and how you intend to grow your dahlias.

As a general guide, allow approximately 25–40 cm between plants.

Large, vigorous varieties may appreciate more room, while smaller varieties can be planted closer together.

Good spacing allows:

● Better airflow

● Easier access for picking

● Room for the plant to branch

● Less competition for nutrients and water

● Easier pest and disease monitoring

Dahlia Nerd tip: You can plant nice and close to squeeze your extra tubers into the bed, just keep up the fertiliser so each plant gets the nutrients it needs 

 Irrigation

Good irrigation is important, particularly once your dahlias are actively growing.

When newly planted, don’t overwater them. The tuber needs moisture, but constantly wet soil can encourage rot before the plant has established.

As the plant begins to grow, gradually increase watering.

Once your dahlias are actively growing, aim for deep, consistent watering rather than frequent light watering.

Remember:

🌱 Newly planted = check the soil doesn't dry out.

🌿 Actively growing = consistent moisture.

🌸 Flowering =  Morning watering is best, Hydrate your plants before the heat of the day

Your soil type, weather and irrigation system will determine how often you need to water, so always check the soil rather than relying purely on a watering schedule.

Feeding Your Dahlias

Dahlias are hungry plants, particularly once they start producing lots of foliage and flowers.

Start with good-quality soil and compost, then provide additional nutrients as the plants establish and grow.

Liquid fertiliser can be useful during the growing season.

Avoid going overboard with high-nitrogen fertilisers, as this can encourage lots of leafy growth at the expense of flowers.

Dahlia Nerd tip: Once the plants start to flower, I use POWERFEED weekly throughFebruary and March

Staking & Supporting Your Plants

It’s much easier to support your dahlias before they become a huge plant.

Large dahlias can become top-heavy, particularly once they’re covered in flowers.

Install your stake or support system when planting, or very early in the plant’s growth.

This means you won’t have to push a stake through an established root system later.

As the plant grows, tie it loosely to the support to keep the stems upright.

Why stake?

🌬️ Helps protect plants from wind
🌸 Supports heavy flower heads
🌿 Keeps stems upright
✂️ Makes harvesting easier

Dahlia Nerd tip: Don’t wait until your dahlia is six feet tall and falling over to decide it needs a stake. We’ve all been there!

 Pinching Your Dahlia

This is one of the easiest ways to encourage a bushier plant with more flowering stems.

When your dahlia has developed 3-5  sets of leaves and is actively growing, you can pinch out the growing tip.

Using clean fingers or clean, sharp snips, remove the growing tip just above a set of leaves.

This removes the plant’s main growing point and encourages it to produce side shoots.

Why pinch?

🌿 More branching
🌸 More flowering stems
💪 A stronger, bushier plant
✂️ More flowers to pick

Dahlia Nerd tip: Don’t be scared to pinch your dahlias! It can feel slightly wrong the first time you remove that beautiful new growth, but your plant will thank you for it and reward you with lots of extra blooms.

 

🌸 And Then… Let Them Grow!

Once your dahlias are planted, watered, fed, supported and pinched, the fun really begins.

Keep an eye on them as they grow and enjoy watching those first buds appear.

Then comes the best part…

Picking your flowers!

And remember:

There is no such thing as too many dahlias.

Welcome to the Dahlia Nerd club. 🤓🌸