What to do with your Dahlia Tubers when they arrive…
Dahlias are tender tubers, they vary greatly in size and shape and often look like a bunch of salamis gathered together.
Dahlias are very similar to Potatoes and if you freeze a potato, at first it appears OK, but will quickly turn to mush when it defrosts.
You must keep your Dahlias frost free and as dry as possible until the weather warms up and you can plant them out.
If they arrive during this cold spell the best thing to do is keep them in the box in your home and in a cool spot, NOT NEXT TO A HEATER!
Mine are in an unheated bedroom, we actually brought hundreds of our most precious tubers up from the shed last week just to be safe (Beast from the East)!
Cupboards are brilliant because they shut out the central heating to a large extent.
If they are stored in plastic just check the bags have ventilation….if not either open them up or cut some slits in the bags yourself.
Once a Dahlia has been brought into a warmer environment it must be kept in damp compost to prevent it drying out and shriveling up. This is how you ‘start them off’…
I start mine in generous pots in March and early April (make sure the Tuber has room to put out roots and grow.
Pots are like shoes for your plants… they need room to wiggle their toes!
They will have formed bushy plants by the time the last of the frosts are over.
You can hold back your Tubers by keeping them cool (and asleep) and then plant them straight out into the garden after the last of the frosts (mid May onwards here in Buckinghamshire) for flowers slightly later.
However you have started your Dahlias you will need to pinch out the tips of the main shoot as they grow.
Either use a sharp knife or squeeze between your thumb and forefinger, remove the main shoot down to the top pair of leaves.
You will also need to remove all but 5 shoots from the sprouting tuber.
This can seem a bit heart-breaking at first but it’s essential! Be brave!
We are encouraging bushy plants and with only 5 stems you will get strong vigorous growth that will produce a lot of flowers!
Too many stems diverts the plants energy into doing too much. As a result your stems will be too thin and floppy to support the flower heads.
Dahlias thrive in full sun, fertile soil with good drainage, if your soil is heavy then a good layer of grit under the tuber will help with drainage and stop the tuber getting waterlogged.
Sitting in water can lead to rot and the loss of your plant.
To plant them, dig a hole about 30cm square and 30 cm deep (12 in), but use your
judgement, some Dahlia’s are bigger than others and over-wintered plants can be much
much larger, you want them to sit comfortably in the bottom of the hole with space to fan out the tubers, not squished in!
Dahlias are also extremely hungry and thirsty plants, incorporate lots of good well-rotted
organic matter to get your Dahlia’s off to a great start.
Place a layer of well-rotted compost or manure in the bottom of the hole (on top of your grit on heavy soil) to give your tuber a comfortable cushion and it’s a good idea at this time to also add a stake (e.g. a Bamboo Cane) so you don’t accidentally harpoon your tuber later!
Note: it’s vital that the organic matter is well rotted, fresh manure or too much plant feed can lead to damage, the leaves will turn brown and crisp around the edges, leading them to look ‘Scorched’.
Back fill the hole with soil and more compost (or manure) and water in well, a full watering can! This will also settle the soil back around the tuber properly and give it a jump start so don’t skip this bit (even if it looks like rain)!
Dahlia’s need plenty of room and depending on the variety you need to space them to accommodate their eventual size and the tuber at least doubling in size of the season, about 45cm at least!
Most import, protect from Slugs! The juicy new growth is like caviar to these naughty
molluscs and they can mow your Dahlias down over night!!
The best slug control is snipping them in half as soon as you see them!
We’ve tried beer traps – Boddingtons was brilliant!
Nematodes are great but for us they would be too expensive so we use also organic slug pellets and put them out sparingly ages before you even think you need them to stop breeding in its tracks.
We also found Chickens are brilliant although you need a careful eye or they will be happily digging up your seedlings as they look for bugs!!
If you do a combination of all these then you can keep the problem under control.