Dahlia Grow-A-Long

Lifting Dahlias in Spring

Left to their own devices Dahlia tubers can strangle themselves in a vice of old and new growth.

This can result in a decrease of flower quality and production. Plants could even perish.

Every few years it’s a good idea to dig them up and regenerate them through division and cuttings.

This is step one. Videos are streamed live from the garden so stay tuned for the next step!

Dahlia Gall

Dahlias can suffer from Gall.

Spring is the ideal time to check your plants to make sure your stock is healthy.

Technically there are two types

Crown gall

Caused by bacterium Rhizobium radiobacter (synonym Agrobacterium tumefaciens) which causes the plant to grow in a disorganised way, producing swollen galls.

Leafy gall

Caused by bacterium Rhodococcus fascians, which again causes the plant o grow in a disorganised way, this time producing dense clusters of distorted, leafy shoots.

The latter seems to be the most common here in the UK. Both bacterium enter the plant through wounds in roots or stems. In this video I explain in more detail including examples.

Dividing Dahlias

After a few years Dahlia’ tubers can build up into congested clumps.

Old dead material from previous seasons growth is mixed with the new tubers created each season. As the clump ages the number of new tubers multiply, interlocking underground and can basically ‘strangle themselves’.

Ultimately congested clumps will effect the quality of the flowers and can cause the death of the Dahlia. You can reinvigorate these clumps by dividing these tubers, removing the spent dead material and releasing the new tubers into smaller clumps to be replanted as well as creating lots of new plants for free!

Dividing Huge Dahlia Tubers

Sometime dividing Dahlia Tubers can be a bit intimidating, in this video I tackle a huge Cafe Au Lait tuber.

Starting Dahlia’s ‘Pot Sizes’

Dahlias are very tender plants that can’t go out into the garden until after the last frosts, Light sensitive Dahlias really come into their own as the days start to shorten but you can get an extra month of flowers by starting them undercover now.

Watering Waking Dahlia Tubers

It can be very easy to overwater you Dahlias, especially when waking tubers up. They don’t have an ‘off switch’ too much water will rot the tuber.

Dahlia Tubers Finding the ‘eyes’

Dahlias shoot from swollen nodes we commonly called ‘eyes’. To be begin with spotting that can seem like a black art. In this video I explain what an eye actually is, why it’s so important. There are also lots of examples to compare against your own Dahlia Tubers.

Dahlia cuttings

Quick easy Dahlia cuttings

Pinching Dahlias

In this video I explain how and why we pinch dahlias with examples of pinched and unpinched plants.

Dahlia Cuttings Update

It’s been 4 weeks since we took our Dahlia cuttings.

Deadheading Dahlias (how to tell new buds and deadheads apart)

Simple way to check for spent blooms when deadheading Dahlias:

New buds are always round as a button

Deadheads or spent blooms are always a pointed cone shape.

Over Wintering Dahlias

How to lift and store your Dahlia tubers for the winter.

How to lift and store your Dahlia tubers for the winter

Rule #1 is keep your Dahlias dry while they hibernate

We don’t wash our Dahlia tubers until the Spring as we find this just discourages the likelihood that they will not freeze or rot.

Rule #2 gentle humidity and ventilation

Over the years we have tried many methods and have found that leaving them with a layer of soil covering them increases success significantly!

This stops them shriveling and getting wizened.

You can use vermiculite instead which works well but it would just be too expensive for us here at Swan Cottage.

Rule #3 steady temperature

Store in a garage, shed or outhouse.

It’s important that you don’t use a shed with a felt roof, these buildings can soar in temperature on sunny days even in January, this will quickly kill off your precious tubers.

Garden shed’s with felt roofs can cause problems when storing dahlia tubers

You need a nice steady temperature, not too hot or the Dahlia’s will try and wake up and not freezing or the tubers will burst due to the high water content in them. Just the same as you can’t freeze raw Potatoes or Tomatoes, they turn to mush on defrosting…

Pick up a Min/Max Thermometer and monitor your proposed storage place.

Storing Dahlia Tubers for the Winter


Pot Grown

If you have been growing your Dahlia’s in a pot, then you can just put the pot, soil and all into a garage, shed or outhouse.

We let the pot dry out completely, then add a scattering of organic slug pellets for super safety.

(Organic slug pellets contain Ferric Phosphate as an active ingredient. … If the pellets (or the slugs which have eaten them) are eaten by birds, mammals etc, they will suffer no adverse effects).

Garden Grown 

In warmer places with very free draining soil you may often ‘get away’ with leaving them in the ground, however you might not be getting away with it as much as you think and 3/4 of the Dahlia could be dying off each year leaving just enough to re-shoot…

Covering your plant in situ with a cold frame will dramatically increase the chances of survival, as long as this keeps the soil ‘dry’ it might not work on a slope or in clay soil…

Field Frames 

Our Dahlia’s planted out in the field under Neil’s frames can be left just where they are.

We have very free draining soil and a fairly flat site.

Once the frost cuts the plants down we turn these growing frames into cold frames by sliding reusable lids low over the plants. We can wrap the whole frame in packing wrap for the ultimate winter protection.

Storing Dahlias over Winter / overwintering Dahlia Tubers
Over Wintering Dahlias in the ground.

We had 100% success with this method even during -10C degree freeze of 2017/18


Dahlia’s that are planted around the garden and don’t have the protection of the frames are lifted!

Storing Dahlias over Winter / overwintering Dahlia Tubers

We lift with in November, lifting with all the soil that does not fall away, Tubers are packed in crates which have fully vented sides and lid so any moisture can easily escape.

Storing Dahlias over Winter / overwintering Dahlia Tubers

We then stack them our tin roofed outhouse (see Rule #3)

During cold spells we pull old blankets over the stack…

Whatever method you use remember to label!