Regular sowing is necessary for regular cropping without gluts. We try to sow a few things every week or two throughout the growing season. This week we started with the cucurbits: summer and winter squash, melons, and cucumbers. I used a mixture of a free draining soil based seed compost with some organic peat free multipurpose, relieved of any large bits of woody material. Cucurbits are rather sensitive to excess moisture; the seeds will readily decay and the young plants collapse under damp conditions, which encourage rots and fungal problems. Whilst some moisture is obviously needed, the compost must be free draining and the pots should not sit in water. The seeds of squash, melons, and cucumbers, are somewhat flattened, and it is common practice to sow the seeds on their edge, supposedly so that moisture sheds from the seed more readily. Whether this really makes much difference or not I have not bothered to find out, but one might as well continue the tradition. The larger seeded squash are planted a good ¾” deep and the melons and cucumbers perhaps ½”.
Our next sowing was of various cipollini – delicious smaller onions of different sorts. Onions grown from seed are often sown earlier in the year, but for these more modest sized bulbs they can, in my experience, be sown until mid April and still produce a useful crop. Sowing from seed has various advantages, including a much greater range of varieties, less likelihood of bolting, and possibly developing better quality bulbs. It is, though, more labour intensive, so at the moment I still use sets for my main crop. I sowed the seed in modules with reasonably deep cells, two or three seeds per cell. I do not usually bother to thin these and plant out together as a clump. As our main onion beds are filled with main crop onion sets, garlic, and shallots, I plant those grown from seed in one of the borders. The main beds are fairly clean of weed now, but the borders are not yet in such good condition, and perhaps they will always be a little more weedy. I therefore wait until the onions have a good root system and strong top growth before transplanting to the border.
We then attended to our first sowing of leeks. This year I plan to grow two varieties, Musselburgh and Bleu de Solaise. This week we sowed Musselburgh and will sow Bleu de Solaise some weeks later. Leeks are one of the few seeds that I sow in seed trays. Perhaps somewhat unusually, I transplant my leeks twice. First I sow in a seed tray, then transplant to a larger, deeper, tray when they are robust enough to handle. These then grow on until they are a good size for planting out into their final positions. This system works well for me, and I prefer it to transplanting once, when the seedlings are inevitably rather weaker than using this system. We have certainly never failed to produce a good crop of leeks. Indeed, they are one of our most reliable crops, and a useful one too, being available for quite a long period from late autumn, through winter, and into spring.
Our final sowing this week was celeriac. Celeriac needs a long growing season, can be a little slow to get going and germination can be somewhat erratic. I would not want to sow after March, and they could perhaps have been sown a couple of weeks ago. Celeriac seeds are very small and I sow in module trays, two or three seeds per cell, thinning to a single seedling. Celeriac seeds need light to germinate, and it is often recommended that they be sown on the surface of the compost and then covered, for example, with a sheet of glass. However, one can add a thin layer of compost, and I have always done so, largely because I did not realise that they were so particular about light when I first grew them. Nonetheless, they do seem to germinate quite well with this light covering of compost, but certainly they should not be sown deeply.