Hartley Magazine

All the latest news, hints, tips and advice from our experts

The Right Temperature & Greenhouse Tomatoes

Spring has been one of the best for years, after several mild winters when plants couldn’t decide whether to be dormant or grow, they’ve responded to a cold rest and sunshine by blooming beautifully, so our spring has been filled with flowers. One interesting feature has been the constant cold winds, which have been present for a month or more. Sunny days have raised daytime temperatures but lack of cloud coupled with a wind chill factor, meant that night temperatures have been surprisingly low and the soil has been slow to warm. The only solution has been to cover the soil with black polythene to raise the soil temperature before preparing seedbeds and sowing – something that I usually do for early crops. However, this year is different and I’m expecting to continue this for a while, until the cold wind disappears. ‘Hardening off’ has become critical too, putting plants outdoors in a sheltered spot during the day and bringing them in at night for two weeks before planting out, ensures that they are tough enough to survive the cold wind and covering them with horticultural fleece or creating a temporary windbreak, for a couple of weeks will help them establish, particularly on windy sites.

Greenhouse tomatoes are growing well now and it is important to remove the side shoots of ‘cordon’ varieties to create a single productive stem. Don’t cut out the side shoots with a pair of secateurs, simply break them off with your finger and thumb. Make sure that your plants are well watered, too, particularly if they are being cultivated in growing bags as the compost dries out rapidly; twice a day is ideal as one large soaking often leads to water-logging. Erratic watering causes calcium deficiency shown by ‘blossom end rot’, later in the season, when the end of the fruit furthest away from the stem, turns black. Lack of calcium can affect apples, too, particularly those with large fruits like ‘Bramley’s Seedling’ and ‘Newton Wonder’. The disorder, known as bitter pit, causes brown spots just below the surface and makes the fruit taste bitter. It usually happens during dry summers and can be resolved by watering well from before they suffer from drought stress, mulching, thinning crops to reduce calcium demands or spraying with calcium nitrate.

During the last bank holiday in May, I visited a local garden centre where customers were filling their shopping trolley’s with bedding plants for hanging baskets and containers. It is always better to plant them up around this time of year, too many people buy bedding plants during the Easter holidays and end up buying a second batch to replace those that were planted out too early and killed by the frost. Keep newly planted hanging baskets well watered, water at least twice a day as the days get hotter; early in the morning, evening and often at lunch time too. Feed your flowers weekly with high potash fertiliser and remove the spent flowers of most varieties regularly for a dazzling display. Happy Gardening!