by John Martin
Stonebridge Farm
We plant in 1″ square cells that are 2″ deep. First we fill the cells fairly tightly, then press a finger into each to depth of about 1/4″. We try for 4 seeds per cell but more is OK too. They transplant very well so if we get a thick cell, we move them around to fill spotty germination. Then we sift soil mix to cover the plug flat, pat it down and smooth it off. At first, watering from below by setting the plug flat in a tray of warm water works best to keep from blasting the seeds out of place. Then onto the heat mat set at about 80° with a clear plastic top on until the seedlings break the soil. Once they emerge, we remove the cap, turn down the heat mat, and water from above. Any time they get longer than about 3 ” we give them a hair cut down to about 1″ with an old pair of scissors. The tops are good in salad and shortening forces thicker transplants and more root.
The plug flats aren’t important – but we have found that a deeper tray of some kind works better. We’ve also used boxes 2″ deep and put the seed into a 1/4 -1/2″ furrow – about 8-10 seeds per inch with rows about 2″ apart.
When it is time to transplant out – first two weeks of April for us usually – they can handle bare root treatment so we wet them thoroughly, break the plugs apart, press them in one at a time 4 1/2″ in the row and 9″ between rows, and water in immediately after transplant.
That works pretty well for us as long as the soil in the flats doesn’t freeze.