[Janeymiddlewife]

This is my 1st year growing from seed. Probably a silly question, but I'm not used to growing flowers :blink:  I've got 50 Carnation superb series mixed and 50 cosmos sensation mixed.
Should I sow them successionally to get a longer flowering, or if i dead head and feed & water will they keep going by themselves - i want to grow them for cutting indoors.  Also about to sow some sweet peas - will try soaking them overnight;

• how tall should they be before i pinch out the tip
• When do they need planting out

• What's the best way to support them - with string like a raspberry support horizontally or up a bamboo wigwam

Thanks 

[Stripey_cat]

They all will flower for a long time, so long as you pick every single flower on the plant so it never sets seed.  So I'd not bother with successional sowing.

You can pinch out sweet peas as soon as they have put out three or four true leaves.  Alternatively, if you want really big flowers for cutting, you don't pinch them out, rub out any side-shoots, and restrict the number of flowers per plant at any one time.  They can be planted out once the soil starts to warm up: unless they're very leggy they will tolerate a bit of frost.

Supporting them is pretty flexible - you can grow them up trellis or let them scramble through shrubs, even.  If you grow them up canes (either wigwams or rows like for runner beans) you need to stretch twine horizontally every 6 inches or so, because they climb with tendrils rather than twining up a cane like a runner.

[Trillium]

I never bother soaking sweet pea seeds as they do fine straight in the garden, but they're a bit slow to sprout in cold soil so this year I'll put them in a bit earlier than usual. Do give them something to climb or they won't flower as well, and do keep picking them which prolongs the season a long time.
cosmos never tire of flowering so just keep picking and direct seed early.
Carnations are a bit pickier and should be sown indoors soon for spring planting.