What Size Pot To Start Dahlia Tubers. Place the tuber in the pot with the central stem upwards and cover with more compost. If you do choose to grow dahlia plants in containers the containers should be at a minimum 15 wide by 15 deep.
Can I pot up my dahlia tubers to give them a head start. Larger size pots would be appreciated by the dahlias but take up more room. Many varieties would do well in a 12- to 14-inch diameter pot which is also at least 12 inches deep.
First check your tuber.
I have found that potting in soil-less compost is not very good for tuber production and keeping and I prefer compost which is more open usually produced by mixing the peat base with John Innes No 3. These lower growths serve to store food for the plant and a plant can do well despite losing several of these. Start by half-filling a 2 or 3 litre pot with peat-free multipurpose compost. You need to start your dahlia tubers off in a 3 litre pot.