Tag Archives: c312

What to do with dahlias after they have finished flowering

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This question was asked by
– Mrs K

Good morning, would you kindly tell me how to store my Dahlia’s over the winter for next year.
Many thanks

Certainly! Overwintering dahlias is all about keeping tubers safe from frost and rot so they’re ready to burst into life again next year. Here’s a simple, step-by-step guide:

1. Wait for the First Frost

  • Leave your dahlias in the ground until the first frost blackens the leaves. This signals the plant to go dormant.
  • Don’t rush — if you lift them too early, the tubers may not have fully matured.

2. Cut Back and Lift

  • Cut stems down to 10–15 cm (4–6 inches) above the tuber.
  • Use a fork to gently lift the clump from the soil, being careful not to stab the tubers.
  • Shake or brush off loose soil — avoid washing with water unless they’re very muddy.

3. Dry Them

  • Let the tubers air dry in a frost-free, dry, airy spot (like a shed or greenhouse) for about a week.
  • This helps prevent rot in storage.

4. Clean and Inspect

  • Remove any remaining soil.
  • Check for damaged or diseased tubers — discard any soft or mouldy ones.

5. Store Correctly

Place in a box or crate with dry material such as:

  • Dry compost
  • Peat-free compost
  • Vermiculite
  • Sand
  • Make sure tubers don’t touch each other — keeps rot from spreading.
  • Store in a cool, dark, frost-free place (around 4–10 °C / 40–50 °F), like:
  • Garage (if frost-free)
  • Shed
  • Spare room
  • Cellar

6. Check Monthly

  • Every few weeks, check for signs of rot or shrivelling.

  • If shrivelling, lightly mist the storage medium.

  • If rot, remove the affected tuber immediately.

Extra tip: If you’re in a very mild area, you can leave dahlias in the ground over winter — just cut back and cover with a thick mulch layer. But it’s always safer to lift them if your winters are frosty.

The Hart Family

Soil requirements

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This question was asked by
– Barbara K – 

I have alkaline clay soil, what would be suitable to order and plant?

Hi there,
If you have alkaline clay soil, you’ll want to choose summer-flowering bulbs that are tolerant of less acidic, heavier soil. While some bulbs prefer slightly acidic conditions, there are plenty of summer bulbs that thrive in alkaline clay soil. Here are some great options for your garden:

Suitable Summer Flowering Bulbs for Alkaline Clay Soil:

  • Lilies (Lilium) – Many lilies, especially Asiatic and Oriental hybrids, will do well in alkaline soil. They need well-drained but moist soil, and they’ll grow beautifully in clay with added organic matter to improve drainage.

  • Gladiolus – These thrive in a variety of soil types, including alkaline and clay. Their bright, spiky blooms are perfect for adding drama and height to borders.

  • Alliums – Alliums (such as Giant Allium and Purple Sensation) are perfect for alkaline soils and will add striking, globe-shaped flower heads to your garden.

  • Dahlias – Dahlias are very adaptable and can grow well in clay soil if it’s enriched with organic matter. They thrive in alkaline conditions and will produce vibrant, large blooms throughout summer.

  • Canna Lilies – These tropical beauties love a rich, moist soil and will thrive in your alkaline clay soil with a bit of organic matter to improve drainage.

  • Crocosmia – Known for their bright orange or red flowers, Crocosmia (also called Montbretia) thrives in alkaline soils and will add a pop of colour to your garden.

  • Begonias – Tuberous begonias prefer slightly acidic to neutral soil but can grow well in alkaline soils with added organic matter. They are perfect for pots or hanging baskets.

  • Eucomis (Pineapple Lily) – These unique, tropical-looking plants are perfectly suited to alkaline soils and add a fun, vertical element to your garden.

Oriental Trumpet Lily Conca D’Or will be happy in any well-drained soil.

Tips for Improving Your Clay Soil:

  • Amend with organic matter like well-rotted manure, compost, or leaf mould to improve soil structure and drainage.

  • Consider adding grit or sand to increase the drainage for bulbs that need it.

  • Mulch around plants to help maintain moisture levels and keep the roots cool.

Advice regarding overwintering of dahlia plants

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This question was asked by
– Fliss T

Hello

Please could you advise me as to whether it would be best for me to remove the dahlia tubers and store them over the winter or to leave them in the ground.
As well as enjoying the beautiful dahlia flowers which has given me and my friends and family so much please.

Dahlia Thomas A. Edison

Dahlia Thomas A. Edison

Hi there,

Please see below on how to care for your dahlias once they have finished flowering and how to overwinter them:

How to care for Dahlias

Aftercare/Overwintering

    • Once your dahlias have finished flowering and the first frosts have blackened the foliage, cut the plants back to the ground.
    • In well-drained soils, leave the tubers in the ground and mulch over to protect against frosts.
    • In colder climates or heavier soils, lift and store your tubers over winter.
    • If lifting and storing over winter, cut back foliage and carefully lift the tubers out of the soil. Allow the tubers to dry off naturally and then clean away any soil. Trim the stems back and cut off any fine roots. Make sure the tubers are completely dry before storing them into open trays or boxes. Pack with dry sand. Leave the crowns exposed.
    • Replant the following spring.
    • Must be kept frost free.
    • Once the risk of frosts have passed and you start to see signs of growth again, the mulch can be removed.
    • Water regularly during active growth periods.

Care:

    • Support Dahlias with canes on planting and tie in as growth develops.
    • When your Dahlias reach about 40cm in height, pinch out the growing tips with your thumb and forefinger or use a sharp knife. This will encourage branching.
    • Water once a week with a good amount not just a little sprinkle.
    • Deadhead flowers as they fade.

Overwintering:

    • Once the first frosts have blackened the foliage, cut the plants back to the ground.
    • If panted in the garden, in well-drained soils, leave the tubers in the ground and cover with a generous layer of bark chips or compost to protect them from frost.
    • In colder climates or heavier soils, lift and store your tubers over winter.
    • If planted in pots, cut back the entire plant to 4 – 6 inches. Keep the dahlias in their pot over winter. Keep the pot in a cool, dry, dark place that doesn’t freeze like a garage, shed or greenhouse.
    • Don’t water your tubers, just let them stay dry.

Lifting and Storing over winter:

    • Cut back foliage and carefully lift the tubers out of the soil.
    • Allow the tubers to dry off naturally and then clean away any soil.
    • Trim the stems back to 15-20cm and cut off any fine roots.
    • Make sure the tubers are completely dry before storing them into open trays or boxes. Pack with peat-free compost or dry sand. Leave the crowns exposed.
    • Replant the following spring.

 

The Hart Family

New to Dahlias

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This question was asked by
– Simon –

Hi, I have a raised bed 7′ x 4′ and would like to use it to grow dahlia for cut flowers.

The soil is sandy and has been dug over and weeded.

How would you advise if plant it…..how many tubers in this space please.

Any recommendations for a newbie.

Many thanks

Simon Town

Hi

Dahlias have specific spacing needs for optimal growth. Typically, most Dahlias require a space of about one square foot per tuber. This is to ensure that they have enough room to grow without competing with each other for resources. However, the Dinner Plate Dahlias, which are among the largest varieties, need a bit more space. They should ideally be spaced 12-18 inches apart. This additional space allows for their extensive foliage and large flowers to flourish. On the other hand, the more compact Dahlia varieties can share space comfortably. Multiple tubers can be planted together in each square foot, as these types don’t require as much room to grow.

Dahlias

Growing dahlias

The Hart Family

Dahlia advice

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This question was asked by
– John H – 

When buying Dahlias from you the alternatives are 1 tuber, 3 tubers etc.
how many do I need for each of 2 very large pots/planters?
For example “Bishop of Llandaff”

Thank you.

Dahlias do get quite big and if you pinch them out they spread out quite a bit too. I would advise planting 1 x dahlia tuber in a container that is at least 12” deep and 16” wide. The bigger the pot, the better. Each dahlia tuber needs 12” x 12” x 12” of space to grow well. Don’t plant too many dahlia tubers in one pot.

Bishop of Llandaff

Bishop of Llandaff

The Hart Family

When can I order Dahlias for planting next year

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This question was asked by
– Michael R

I want to order more dahlias for next year.
I was very pleased with the one’s you sent me in March.
Thanks Mike Robson.

Hi there,
We will be putting our Dahlias back in stock very soon. You can be notified by email when they are back in stock if you click on the button ‘tell me when this is back in stock’ on the product page.

Dahlias

Hope this helps.

The Hart Family

Planting of Dahlias

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This question was asked by
– Veronica M

I have just purchased from you 3 tuber “Little William”
I am planting these tubers in pots.
Could you please tell me how deep I need to plant them ?
Thank you. Veronica McLaughlin

Hi there,

Dahlias need planting just under the soil surface so cover your dahlia tubers with about 3cm (1-2″) of soil.

Dahlia Little William

The Hart Family

Thank you!

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This question was asked by
– Colin F

hi some time ago I ordered some dahlias from you and they arrived last week.just a thank you to all of your staff for the excellent service and delivery. Keep up the good work and once again many many thanks Colin.

Hi Colin

You’re very welcome. Thank you so much for taking the time to email us. We would really love to share your experience with other customers, if you get a moment we would really appreciate it if you would leave us a Trustpilot review. https://uk.trustpilot.com/review/hartsnursery.co.uk

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The Hart Family