The polytunnel in September

This is the month of the equinox and just as the days get shorter so the polytunnel grower needs to make plans for the winter.

Many people don't use their polytunnel intensively during September to March, which is a huge shame considering the investment that has been made.

In my polytunnel I have now got purple sprouting broccoli which is a metre high and looking well. Whilst the soil remains warm it is worth feeding these plants and getting them to be as big and healthy as possible before the start of the worst cold weather.

As space becomes available sow spinach now, this will grow into small plants which will overwinter and produce a good crop early in the spring. Keep it well watered during the warm days but reduce watering as the weather gets colder.

The overwintering onions are in their modules waiting for the space to become available for them to be planted. Although the seed merchant says don't transplant I have never had a problem. I transplant the seedlings when they are very small, and try to get them planted before mid October. They then usually have a good month of reasonable weather to put on some growth, but don't expect them to look too substantial. It is quite astonishing how even quite wispy seedlings will tolerate extremely cold weather and go on to produce good sized onions.

Winter kale plants and lettuces get planted as space is cleared. The kale needs to be planted in the area reserved for this season's brassica plants, but lettuces and spinach can be planted wherever you like because you do not need to worry about rotation for these vegetables. However I still try to avoid areas which have been growing these plants recently. I tend to leave the labels in the ground so that I have a means of checking what has been recently grown in that area -  this only works if you put the date on the label and the writing doesn't fade! I find pencil lasts longer, and then when you do lift the label you can rub out the writing and reuse.

This year I sowed some leeks much later than usual (June), and these were put in the polytunnel. They are a nice pencil thickness now and growing strongly, I plan to use them as baby leeks during the winter. The outside ones don't overwinter well here and are difficult to lift as the ground becomes more frozen. I expect they will be used up by December, and then my indoor leeks should be a reasonable size and much easier to harvest!

My latest experiment involves asparagus. I have been promising my husband that I would grow asparagus for years. Fresh asparagus is incomparable to shop bought. Unfortunately the first crowns I bought struggled to survive and were finished off by the winter 3 years ago. I am reluctant to permanently give up significant space in the polytunnel to one crop, so I am trying a more ruthless method of production. This involves seed raised plants (I've chosen 'Connover's Colossal'), potting them on (now they are in 3 litre pots), and planting them out into their harvesting position this month. They are going into the sweetcorn bed. They are handsome looking plants with a number of ferns each, some of which are about the thickness of a pencil. The protection of the polytunnel and the slightly raised bed should mean they come through the winter quite easily, allowing you to harvest whatever grows. They grew very easily from seed, so much so that I have 10 to plant this year but some others will be kept in their pots, overwintered in the greenhouse, and grown on as 2 year old plants to be planted in the polytunnel next autumn. I will report on the success (or otherwise) of this experiment.

The carrots grown this year will remain in the ground and be used as required. Generally at least one row of them will have been finished by February which is when I will be looking for space for the first of the sugar snap peas. They will be started in pots in the greenhouse and then we are swinging around to the next season and the March equinox.