It is too early to start sowing seeds for summer plotting, but the 21st December should be marked by a sowing of seeds of some kind. Today is the winter solstice; the shortest day of the year. From now on the days will get longer. Light levels at this time of year are low. If you start sowing maincrop seeds, however tempting, they will probably founder before you are able to transplant them outside.
But it is never too late, or too early to sow all year round Mesclun.
Mesclun is the French term for a mixed sowing. You will also see the term Saladini, which was coined by the doyenne of salads, Joy Larcomb. There is very little limit to what you can mix into such a salad basket. There are some lovely pre-mixed varieties available, or you can mix your own. It is a great way of using up left-over seeds. Because the leaves will be eaten early, you can use any of the beets, spinach, cabbage, roots, herb or lettuce cultivars. Consider also the Chinese groups of leaves like Mizuna, Chinese cabbage or Pak choi. There is also a host of cultivated weeds that grow well in winter that our ancestors would have recognised, but modern gardeners might not think of Good King Henry, Winter Savory, Salad Burnet and Golden Purslane.
Do not worry if the packet recommends that some of the seeds are sown deeper than others. Do not worry if some of the seeds take longer to germinate or come to fruition. The haphazard nature of the enterprise is part of its charm.
My winter mix last year was:
Basil - sweet
Lambs Lettuce Gala
Lettuce Lollo Rosso
Kale Nero de Toscano
I sow into small trays, which have been almost filled to the brim with two inches of potting compost. You can buy special trays, or modify supermarket trays by piercing a few drainage holes in the bottoms. Sprinkle the seeds fairly thickly, about 20 seeds in a pot, three inches by five inches will suffice. Then sprinkle a ¼” of fine compost on top. The seeds will not be fussy about growing medium, but potting compost does have more fertilizer in it than seed compost, so this will fortify the seedlings as they grow.
Water sparingly, but do not let the seeds dry out. Once the seedlings come they need very little water in winter. Once the sun gets up and condensation forms on the inside of cloches or plastic covers, they will gt a free drink every morning.
The books tend to recommend sowing once a fortnight, for a reliable winter supply. But I don't hold with that. It is better to sow a lot of seeds in September or October and just harvest them at different stages. Things like basil won't last long, but are delicious as micro greens, while stallwarts like lambs lettuce and Americal land cress will grow and grow.
Do not plant in a heated propagator. Normal room temperature, as long as it remains above 15°C * during the night, is fine. Remove the covering as soon as the seeds surface. Failure to do so may result in diminished light levels and spindly, etiolated seedlings.
Once the seeds start to show you can harvest them in a number of different ways:
Snip off the seedlings at the root of the stem once the first cotyledonleaves are visible. The leaves will be small and precious. At this stage they will be at their most tasty and nutritious.
Leave the plants a little longer, to develop their first true leaves and you can cut a more substantial leaf salad. At this stage the individual seeds may start to crowd one another out, so your first harvest can be a thinning out, taking say, every other plant. You can cut the leaves or carefully hook them out root and all. Imagine your tray divided into one inch squares. Leave one strong plant per square to develop further.
If some of the seedlings you root out look strong, they can be transplanted into small individual pots and grown on. An individual lettuce will grow to heart and can make a salad in its own right. If you are overrun with seedlings later in the spring, you can take the whole pot and transplant it outside. This picture shows a mix of Chinese Mesclun that I nurtured to maturity in 2011. The Russian Kale went on to form large individual plants which provided a useful addition to stir fries right through the summer. Instead of hardening off the tray, I transplanted each individual seedling under a jam jar. The bed looked a little odd, for a while, but everything endured well.
Later on my thinned salad leaves will grow bushy and I can give the whole tray a haircut once or twice. I leave the growing bud at the base of the leaves. That is a the part that will re-sprout. Feed with a dilute foliar feed between haircuts.
Allowing seeds to mature in-situ:
Even if you give the whole pot a haircut, you could leave a few plants un-cut, allowing them to mature in-situ. The pleasure of this type of gardening is that different things will take off at different times. In the depths of winter, a fresh cress harvest, grown in the space of a few days, will taste delicious. As the days lengthen, the leaf vegetables will start to develop. You will have lovely mixed leaf salads and you may be able to grow on some interesting lettuces or Chinese vegetables to early maturity. Later even plants like Basil and Amaranth will be capable of potting on and planting out, if you allow them a little heat.
*Rocket, Basil and Amaranth require slightly higher minimum temperatures for germination. 18°C is best, however if you leave the trays in too warm a room, the temperate lettuces will find it too hot for germination. Their maximum germination temperatures are about 25°C. If you plant a mix, then regardless of the temperature levels in your room, something ought to come up!