Lucy Chamberlain’s Fruit and Veg
Want to know the secrets to the tastiest glasshouse tomatoes? Lucy Chamberlain explains why growing under cover is reliable, fun and easier than you think…
IF you’re lucky enough to have a greenhouse, chances are it’s full of these tangy fruits all summer. Not only a salad and sauce essential, tomatoes are also packed with lycopene, which is known to help fight cancer and heart disease. My retired smallholder parents grew thousands of glasshouse tomatoes each year, and this is where I cut my horticultural teeth. Now is the time to sow to ensure success with toms, so how do you ensure bumper crops?
Although you can buy plants from garden centres, many of us sow toms because it offers the widest selection of varieties. Germination is strong and swift: sow eight-10 seeds on the surface of a 31/2in (9cm) pot of well-watered seed compost, top with vermiculite and then place in a well-lit propagator at 18-22°C (64-72°F). Multi-directional light is vital to deter leggy growth.
Moving on up
Prick out into individual pots once 21/2in (6cm) tall, positioning at ever-increasing spacings in a 15°C (59°F) spot. As they grew taller, space them out more (again, to deter legginess). Then, as soon as the first tiny flower truss appears, they can be planted into the greenhouse earth. This was my parents’ trump card; many growers would use hydroponics, but soil cultivation does give a better flavour.
More vigorous ‘grafted’ plants are available, boasting bigger yields (up to around 75%) and improved disease resistance via a supercharged root system. However, these come at a price (often £5 per plant), so I still primarily sow instead. You can ensure a bumper root system by growing in the greenhouse border (my parents’ preferred method) or in large tubs or ‘planter’ growing bags.
Although most glasshouse tomatoes are trained as a single-stemmed cordon, you can also try double or even triple cordons, where two or three main stems are allowed to grow. With increasing stem number comes decreased fruit size, so use this for cherry types only.
Fluctuations in water or temperature can cause problems like blossom end rot and whitewall, whereas dry air can give poor fruitlet set or ‘cat-faced’ fruits. Automatic irrigation kits and auto-vents help to avoid extremes, as will irrigating overhead on hot days. With regular highpotash feeding to boost yields, this will be your year for top tomato action!
“Sowing tomatoes gives the widest range of varieties”