Sowing overwintering crops

Polytunnel cleared of autumn crops and ready for overwintering

I am generally rather bad at sowing for the late winter, and keeping such things as winter saladings growing, and I really need to improve that if we are to get diverse produce all year round. The polytunnel certainly makes it easier at this time of year, when outdoors it is becoming rather cold and miserable; the polytunnel can still be very warm even on cloudy, windy, and rainy November days. Although I have not bothered too much about general winter crops – I am bogged down with some house renovations at the moment – there are some vegetables that are ideally sown in the autumn for late spring harvests: peas, broad beans, Japanese onions, shallots, and garlic.

Although one can plant all of these crops in the spring, an earlier harvest should be possible by establishing them now and overwintering. For some crops, there are further advantages: broad beans, for example, are less likely to be affected by blackfly, partly because they will crop earlier, but also because the plants will harden up and be less amenable to sap sucking insects; garlic will also benefit from the winter cold, as a certain amount of chill is needed to encourage cloves to form. Some might advocate an earlier sowing of these crops, and admittedly November is on the late side, but it really depends on local conditions. For us, in our sheltered southerly location, and with the protection of the polytunnel, there is still plenty of time for them to get established before the poor light levels and harsh weather finally brings growth to a near halt. In any event, I cannot sow earlier as I need to wait until the autumn crops – particularly the tomatoes and peppers – are cleared and the beds improved with some manure, before they are ready for overwintering crops.

Although I have sown all of these crops outdoors in the past, I have now abandoned the idea. The broad beans can cope quite well with frost, but they do suffer if there is a prolonged sub zero period. The peas do rather less well, and having taken a battering, I am not sure that they recover sufficiently in the spring. Both can be ravaged by the winds unless steps are taken to shield them. Onions, shallots, and garlic, fare better with the cold, but the wet winter conditions, even on our reasonably free draining sandy loam, results in some losses to rots. If I did not have the polytunnel, I would certainly look to erect some protection – perhaps a wooden frame covered with a polythene sheet – although it is important that there is good air flow, as stagnant damp air is also likely to cause problems.

With the polytunnel, though, the prospects for a good harvest are much improved. The only possible issue is with the pollination of the broad beans, which will flower much earlier in the year, when there are few insects around. Poor pollination will result in only partially filled pods, and we did experience some this year. Thankfully, we seem to have healthy population of bumblebees, and a worthwhile crop can be secured even if there are a few half empty pods. For the onions, shallots, and garlic, the polytunnel will provide good growing conditions and, if it is anything like this year, an early harvest of very good quality bulbs.

All of the alliums were sown direct. This winter I am sticking to my best performing varieties from previous years: Senshyu Yellow onions, Jermor shallots, and Thermidrome garlic. We sow a double row of onion sets and shallots down the side beds, leaving enough space to plant out the tomatoes and peppers in between. The garlic was sown in three rows in the bed at the end of the polytunnel. Spacing of the onion sets can vary somewhat depending on how large one wishes the bulbs to become, but 5 inches is a good start. Similarly for the garlic. I allow 6 or 7 inches between shallots, as these can become quite large clumps next year. All are buried so that just the very tip is showing through the soil. Any soft or mouldy onion sets are discarded, and any spares sown in pots so that any failures can be replaced. With the garlic, it is only worth planting good sized cloves, discarding any that are small, soft or mouldy. In total, we sowed 196 onion sets, 40 shallots, and 48 cloves of garlic. There will inevitably be some losses, but, short of some sort of disaster, this should give us a great harvest next summer.

Although the peas and beans can be sown direct, I prefer to start the beans in pots and the peas in lengths of guttering. The latter is not something of my invention – I do not know who first suggested it, but it seems a common enough recommendation, and I have done it this way for some years. I have cut some old guttering to just over four foot lengths, to suit the width of our beds. Once the peas have germinated and developed sturdy young plants, a shallow trench can be drawn out of the bed and the entire row of pea plants slid into place, where they will establish themselves quickly and reliably. If guttering is not available, then seed trays or modules can be used, but planting out will be rather more of a chore. In any event, sowing in containers first allows the peas and beans to be more readily nurtured, and planted out when sturdy. They are also a little easier to protect from mice, which can otherwise destroy a sowing of peas. I use an organic compost – usually Vital Earth or Horizon, the former tending to have, in my view, a rather better texture – and add a sprinkle of fish, blood, and bone, as a slow release fertiliser. I sow broad beans one to a three inch pot, pushing the seed deep into the compost, so that it is covered by at least an inch. The peas are laid out roughly in a double row, quite close together, and just pushed below the surface of the compost and the soil ruffled over the top. The compost is thoroughly wetted and will be kept just moist. Germination should be fairly quick, as conditions are still quite good in the polytunnel. They will be planted out when suitably robust, and will then overwinter in the beds.


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