Oops, I seemd to have missed tips for April:
DAHLIA JOBS IN APRIL
Keep on taking cuttings until you have made sure that you have sufficient for your needs, although, the back end of April is getting a bit late for the plants to mature fully when planted out.
Prick out dahlia seedlings as soon as they are big enough to handle and put into trays or pots. Pot up the rooted cuttings into 90mm pots using a loam based compost such as John Innes No1. We advise customers not to use multi purpose composts as it tends to kill recently rooted, tender dahlia cuttings.
By mid-April some of the early cuttings will now be getting well ahead in their 90 mm pots; it's time to pot them on into 125 mm pots so that their growth is not set back. Especially important if you have bought ex-pot plants from a commercial grower.
Keep the hygiene programme going! Any plants found to be diseased should be destroyed (burnt) as quickly as possible to prevent spread.
Plant out divided tubers about the middle of April.
Dahlia jobs in May
All your plants should be in 5 inch / 125 mm pots by the middle of May. Stop plants when 5 to 6 inches, 125 mm 150 mm, tall or after 4 -5 pairs of leaves depending on the number of main flowering stems you wish to have. Plants, whether seedlings or cuttings, should now be in your cold house or frame hardening off; do protect from frost!, if real chill threatens a fleece covering will do a great job.
Take any late cuttings should you need to produce plants for tuber stocks. These will grow on but not begin flowering until, probably, late-August but will consequently go on longer if there are no frosts in late October / early November. Keep your hygiene programme going.
In the south and south-west start planting out dahlia plants when the weather is suitable and there seems to be no risk of a late frost. As things are at present with the weather I anticipate beginning the planting out around the 3rd weekend in May.
