I am quite enjoying the sudden cool, and it is leading to a bit of a changing of the guard in the greenhouse. While this has until now been an incredible summer for anything that loves heat – tomatoes, chillies and even aubergines currently thrive in both greenhouse and polytunnel – there is one crop I have been struggling with, and that is lettuce. Lettuce isn’t keen on heat, and is best suited to the milder corners of the year. In a heat wave seeds fail to germinate, and existing plants go to flower and seed, their leaves becoming bitter to the taste. The couple of sowings I have made haven’t come to much, and now I find myself in the dog days of summer and without a lettuce to call my own. It’s a sorry state of affairs, but one that a spell of cooler weather should remedy.
There are tricks I could have employed to get my lettuce moving earlier, of course. Joy Larkcom suggests sowing them in the early evening if the weather is hot. The crucial moment for germination occurs a few hours after sowing, she says, I guess when the seed has soaked up sufficient moisture to be able to switch all its systems to go. If this critical moment happens to occur at midday in a heat wave then germination will be patchy at best, if it falls in the cool of the evening the seeds have a far greater chance of fulfilling their promise. The fridge can do the same trick. My auntie lived in Honk Kong for a while and had a tiny patch of allotment on the roof of an apartment block. Being far from home she yearned for some mild, sweet lettuce, but found it impossible to get going in the constant heat. She had to settle for the far feistier Oriental greens until I suggested she try sprinkling the lettuce seeds into a small bag of compost, wetting it, and leaving it in the fridge overnight before sowing properly in the morning. It worked.
But sadly I did neither of these things in the heat wave, just sowed and then looked on at my patchy germination, disappointed if not particularly surprised. I am making up for it now that the going is a little easier and I have been sowing pots and trays of lettuces in the greenhouse. I do this rather than sowing them direct at the allotment just because I want as short a spell as possible between harvest and eating, where lettuces are concerned. I know that when I harvest crops from the allotment they then have to make it home in a carrier bag and sit in the corner while I pull of everyone’s muddy boots, fetch drinks, tend to scratches and make a cup of tea, by which time my delicate lettuce is limp. So sitting outside in my mini greenhouse, near the back door, are some pots of mixed lollo rosso and little gem, and some trays of mixed lettuce (plus baby beet leaves, for colour). The trays are really for speed. I’ve sown them thick and will harvest them young, almost certainly in the next few days, cutting above the growing tip so that they shoot again, and I’ll get perhaps three cuttings of little 2-inch baby leaves from these trays alone. The lettuces in the pots I can then be a little more patient with, as I should be getting my lettuce fix soon. I will let the little gems develop their crunchy hearts, as this is the lovely thing about them, and the lollo rosso can ruffle prettily about them. Summer can’t be all heatwave: it’s not quite right without a bit of cool, a storm or two, and plenty of lettuce.