Hello Caroline, welcome to the GardenWeb. Lavender should be outside as soon as possible. I am sure it would have no trouble at all in May, in the UK. Congratulations on getting the good start. Lavender is from the Mediterranean area and likes a long hot dry summer, not likely in your area. Here in California it grows like a weed, and we grow a lot of it. Al

Just to reiterate, Caroline, harden them off (should only take a few days now) and put them outside. Plant them out when they reach a reasonable size e.g. 4 - 5 inches.

To harden off you could put them in the greenhouse for a day or two, then outside and in the greenhouse at night for 2 days, then out permanently. This is a very cautious programme. They'd probably be fine going out at once but I'm just being careful.

Although lavender is from the Med it grows fine in the UK as long as it is in soil which drains well. No need to feed lavender at all. You have enough for a hedge! Good luck.

Thanks very much for the advice, they've been in an un-heated green house for the past few days and they're looking fine even though there's been some cold night's. Will start hardening them off tomorrow. Just got to decide what to do with them all now!

Hi again Caroline. I looked up your member page to find your location, and mentioned the UK in my answer to bring out UK gardeners like Flora uk to also answer your post. If you would edit your name to show your location you would get more responses from gardeners in a similar location to yours. Al