I have wintersown delphs several times, not a big deal to transplant. Just be sure to take up all the roots, and don't bury the stems. They are sensitive to crown rot, so if you bury them too deep, they won't do well. They do like a fertile, moist soil, very hot temps or not to their liking.

outside in full shade for a few days ..

then a few days in morning or evening sunlight ...

then out into blinding sunlight..

its called hardening them off to sunlight .. nothing in the house compares ..

i would transplant on a cloudy or rainy day ...

the same for hardening off to temps.. for others.. as i assume you z8 is probably all set in that regard for this spring ...

ken

Hpny2, what size do you let them get to before you finally transplant? My seedlings are so small right now. They have true leaves, but are just tiny. Do you usually wait until fall when they're a bit beefier? I've been debating on when to plant them out.

If you have slugs and snails they'll need protection. Delphiniums are Gastropods caviar.