One of the best things about having a greenhouse is the possibilities it gives you to extend the seasons. It is at these moments in the year – when the seasons are starting to shift from one to the next – that mine really comes into its own. That thin layer of glass ups the temperature a degree or three, and in spring that brought summer on sooner, and allowed me to start some plants far earlier than I would have been able to outside, and so get the head start on the growing year that is coming to fruition now. And then at this time of the year it makes the difference between fooling my plants it is still high summer, and having to admit that autumn is almost here. There is certainly a big change in my garden, perhaps particularly marked by having been away for the middle two weeks of August. When we set off for Cornwall everything was green and growing rampantly, with just the hint of ripening here and there. It felt like the height of summer, because it was. On our return home the deepest red tomatoes were tumbling into our hands, the winter squash looked ready to harvest and cure, the swifts had departed and there were just the first tinges of yellow in the street trees. Summer is still hanging on, but something has shifted. We are suddenly in the foothills of autumn.
My mind quickly turned (after harvesting and eating many, many wonderful tomatoes, so ripe that the juice drips down your chin like you’re on holiday in the south of France) to what to sow next to make the most of the warmth of the greenhouse while it lasts. I’ve started off with a sowing of hardy lettuce ‘Green Oak Leaf’, which wont mind the dropping temperatures and will be quick, giving me something green and fresh from late autumn. This is actually a really good time for sowing lettuces, better almost than any other time. They hate heat and particularly struggle to germinate in hot weather, and if you sowed in summer and had patchy or minimal germination, that is why. A good trick for sowing them in summer by the way is to do so in the early evening. The critical moment – when they decide whether or not the weather is just right for them to germinate – occurs a few hours after sowing, so by doing it in the evening you make sure that this moment falls in the cool of the night, and you hopefully bag yourself some better germination. But even then, heat can make the young plants run to seed before they have put on much leaf, which is frustrating. As we are heading into cooling temperatures mine should germinate easily and then should leaf up well and make some good autumn salads.
I’ve also sown half a tray of mixed leaves which may not prove particularly hardy but should be even quicker, as I will harvest them when they are babies, cutting them an inch or so above the compost in the hope that they will re-sprout a couple of times. They should keep going as long as the weather doesn’t turn harsh too early, and it generally doesn’t here in Bristol.
Some other things you can sow now: oriental leaves, spinach, swiss chard, rocket, spring onions and winter purslane. All will germinate well in the gentle warmth of late summer, and keep growing as the weather cools. It is a good time to spend a few minutes sowing in order to ensure you have lots of interesting leaves to hand for winter and early spring salads and stir fries.