The summer of 2018 in England was the hottest since records began in 1910. For Dulwich gardeners with hoses, gardens could be kept watered as Thames Water didn’t institute a hosepipe ban. However, what was the effect of the long dry summer on Dulwich’s allotments, notorious for their clay soils?
The main challenge to keep the allotments green and productive was keeping them well hydrated. At Grange Lane allotments, mains water supply is augmented by rain, water from springs that periodically surface at the site, and streams which form the source of the Effra and Ambrook rivers, all of which is captured in communal water butts spaced throughout the 200 plots. Maureen Erny, secretary of Grange Lane, had to visit her plot to water every two days during the hottest spell of the summer, while June Marks, the plot holder at Rosendale Allotments who inspired this article, had to water daily. At both sites, watering is permitted by watering-can only -, hard work even during a normal summer, and especially good for the muscles in such hot conditions!
This sounds like a recipe for disaster for all but the most dedicated waterer. However, many crops thrived and those that were not so successful are not entirely predictable. The prolonged hot dry weather seems to have greatly reduced the perennial problem of tomato blight, with gardeners from both sites reporting bumper crops of early ripening tomatoes. Tree fruit seems to vary depending on when the trees flowered; a big storm at flowering time meant no apricots for Sarah Knight (lettings manager at Grange Lane). Peter Allen (membership secretary at Grange Lane) had his best-ever crop of almonds, although the weekend before he planned to harvest them, an opportunistic squirrel stripped the tree of all the fruit. Sarah Lyness at Grange Lane reported her first cucumber and fantastic sunflower growth, she had cut sunflowers on her kitchen table for two months without pause. And Patricia Hole, also a plot holder at Grange Lane, had very good yields of soft fruit: tayberries, loganberries, blackcurrants, and jostaberries (a cross between gooseberries and blackcurrants).
June Marks had abundant tomatoes, pumpkins, squashes and courgettes at Rosendale Allotments, but poorer potato crops (suppliers have indicated that seed potatoes and onion sets may be more difficult to get hold of next year).
For plot holders with more unusual varieties there were some great successes. Jan Davison at Grange Lane had wonderful yields of chillies, chickpeas and a variety of Charentais melon called ‘Emir’ - which produced eight ripe melons!
The dry weather was a great help in reducing the numbers of insect pests including aphids and blackfly, and slugs and snails over both sites. This was particularly welcome at Grange Lane where use of metaldehyde blue pellets to remove slugs is being strongly discouraged in order to encourage hedgehogs to the site (they perform the same service). However, at Rosendale an increase in the number of butterflies and caterpillars was noticed - very attractive but not very welcome when growing vegetables.
Aside from the direct effects of the heat and lack of rain on the fruit and vegetables, there were other effects. At Grange Lane some paths became dangerous to walk on as deep cracks developed in the clay soil. On the plus side, grass paths needed less mowing. At Grange Lane a manure ‘gold rush’ was reported - the horses normally in residence at Buckingham Palace, who provide a great deal of the manure used to fertilise London’s allotments, were taken out of London as the temperatures were too high for them. So when manure was delivered to the site, a stampede formed for the limited supplies!
Strategies for preparing for possible future hot summers centre on good soil preparation. Peter Allen practises ‘no-dig’ gardening at his plot, with raised beds with lots of compost and mulch, which helped the soil hold on to moisture. But all gardeners, diggers or not, can prepare their soil in this way. Winter soil preparation will become even more important; incorporating plenty of well-rotted compost or manure into the soil will help drainage in clay soils and maintain hydration during a dry summer. ‘Strulch’ (a proprietary wheat straw garden mulch) is very effective at preventing evaporation, as are mulches in general, ideally applied before summer. Other tips for vegetable plots are planting early to allow roots to develop and keeping growing areas free from weeds to reduce competition for water. Finally, if we continue to have very hot summers, the kind of crops grown may change, Dulwich may reliably grow chickpeas, cucumbers and melons such as those seen this year!