Everything you need to know about growing dahlias from tubers or seeds.  

Planting tubers

If you have tubers from last year or if you buy tubers.  Place tuber in half filled pot and fill around tuber with loose compost + perlite mix (leave in pot in somewhere frost free for 2-3 weeks and then plant in the ground once the last frost has passed).

Planting from seed in a tray

Tray of moist compost filled with 1/4 of an inch to the top. space seeds out about an inch apart then fill tray to the top with compost.

Planting from seed in pots

Fill small pots with lightly compacted compost leaving a small amount of space at the top. then place 2 seeds per pot and cover with a small amount of compost sifted in-between your hands to prevent lumps of compost

Watering seedlings

Use a fine spray bottle to ensure the plants don't dry out when they start growing

Potting on

Fill a medium pot 2/3 of the way full with damp compost. then take your small pot with the dahlia in it and flip it upside-down with having the stalk in-between your middle and index fingers at the base. then lightly squeeze the pot to release the plant into your hand. then flip the plant into the medium pot and fil around it with compost. then fill slightly above the base of the stalk with compost and lightly pack it down

Deadheading

Leave the round and more firm heads that will become flowers and remove the more pointy and squishy heads that will seed. we do this in order to make the plant not waste energy in producing seeds and more-so use that energy to create flowers