Seed from an unnamed shrub seedling of 'Mme. Billy Boiler' planted on December 21 germinated on May 15. When To Transplant The seed flat, of course, will not accommodate the growing seedlings indefinitely. It all depends on the conditions of weather, space, time available, etc., as to whether to transplant the seedlings to individual pots or to open ground. In either case, they require more attention than while in the seed flat.
Potted seedlings require regular and frequent watering.
Also, it is not always easy to find a suitable location with proper temperature, humidity, light and air circulation for potted plants if you do not have a greenhouse. For instance, in March 1957 some of the seedlings in my flat were being damaged by growing through the wire frame covering them. I thought that it would be quicker to pot about two dozen of the tallest seedlings than to make a higher frame cover. I did so, then placed these potted seedlings on shelves in a work shop window. The outside temperature was unusually high during the latter part of March, and very few potted seedlings survived.