Sometimes, gardening questions arise that seem so obvious I wonder why no one has posed them before. A good example cropped up last week when I was asked why uneven or erratic watering – an expression that appears in numerous gardening books – is blamed for many of the ills that befall plants in the height of summer, and this scorching year especially. It refers to the practice of watering a plant assiduously for a period and then neglecting it – something done all too readily when busy gardeners have to contend with holidays and hot weather.
The most common consequence is for fruit and vegetables to split, and this happens because tissue growth proceeds slowly when water is in short supply, then rushes on apace when it becomes available again. Apples, plums, cabbages, courgettes, cucumbers and especially tomatoes are all likely to show the symptoms.
Tomatoes and peppers display another common effect of erratic watering: a disfigurement misleadingly called “blossom end rot” in which a dark lesion – not actually a rot – appears at the end of the fruit once occupied by the blossom. The way this symptom arises is different, because here the shortage of water leads to a shortage, in the fruit, of the element calcium: this deficiency directly results in the lesion (which, incidentally, does not affect edibility). In consequence, this is the time of year when many a tomato grower converts from using growing bags to ring culture beds in future, the former being quite the easiest way to induce blossom end rot, and the latter the best way to avoid it.
I am sure uneven watering will be unavoidable in most gardens this summer, but to help save water for those plants most in need of it, I shall repeat my oft-given advice never to waste valuable water on a lawn. Lawn turf is well nigh indestructible, whereas tomatoes and their like are not.
This summer brings us something else, frustrating and extremely common: bolting. We should not be surprised when plants fulfil their allotted role in life and bolt or run to flower and seed – but if they happen to be vegetables, it is hard to be sympathetic with them. Despite my best endeavours – incorporating masses of compost last autumn in order to aid the soil’s moisture retentiveness – and despite using my precious water almost exclusively on the kitchen garden, vegetable after vegetable has bolted.
Of course, I expect it of some of the onion tribe (shallots especially) and spinach, while lettuces, even the more bolt-resistant such as “Lollo Rossa”, shoot upwards eventually. But my beetroot “Boltardy” has also run prematurely to seed, along with rhubarb chard, endive and curly kale.
The commonest cause of bolting is that the plants have been exposed to cold temperatures at a critical stage of their early growth and nothing, not even prolonged exposure to high temperatures, can reverse this. In Oriental vegetables, which bolt at the drop of a hat, it arises from an inter-relationship between temperature and day-length, and is best circumvented by sowing fast-growing varieties after midsummer.
At this time of year, however, it is almost entirely the growth check brought about by the erratic availability of water that gives a signal to the plant that its survival is threatened. As with many other living things under such threat, the plants do the only thing open to them – and reproduce.
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This article appears in the 08 Aug 2018 issue of the New Statesman, The rise and fall of Islamic State