Gardening: Your guide to growing top-notch greenhouse tomatoes | Brian Kidd

We must consider whether to shade greenhouse tomatoes. If you decide to use the spray-on variety, the sun will never return and you’ll have the devil of a job cleaning it off.

Friday, 5th June 2020, 5:52 pm
Updated Friday, 5th June 2020, 5:52 pm
To shade or not to shade? That is this week's question for your greenhouse tomatoes. Picture: Shutterstock

Large sheets of newspaper clipped to the plants’ canes or strings are easiest. This can be done on mornings when it’s going to be hot and taken off when it’s dull. Keep the temperature moderate all summer and tomatoes will set properly.

Shading, particularly when the flowers appear, helps stop pollen overheating. Too hot and pollen grains – live cells – die and the flowers fall leaving pea-sized fruits.

As so many of you enjoy growing greenhouse tomatoes, this feature is about how to combat the problems we all have with tomatoes.

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Whichever planting method you use, try to water in the late evening from now. Plants absorb water far better at night.

Once the first truss of fruits are pea-sized, add a quarter-strength liquid food to the can at each watering to ensure even growth and quality fruit. They’ll be even tastier if you use food especially formulated for tomatoes.

Regular feeding also ensures the fruits aren't too acid tasting. They’ll have more flesh rather than a lot of seeds and hardly any flesh.

Keep windows and doors open when it’s going to be hot. Don't worry about a light breeze, it will help pollination, but the plants don't like cold draughts as rapidly-changing temperatures cause poor pollination.

At lunchtime give the strings or canes a sharp couple of taps and you’ll see pollen falling on to lower blooms.

If fruits turn brown around the scar where the flower was, it’s down to poor watering. Overcome it by watering in the evening rather than when you feel like it! Add a small amount of calcium nitrate.

Later in the summer leaves will show signs of deterioration. Look for brown patches which occur suddenly overnight. This is tomato blight. The remedy is spraying in the evening with copper fungicide..

Whitefly are the worst pest for tomatoes but they can be controlled. Yellow sticky cards at the tips of the growing plants and moved up every week, reduce the population. Remember, one whitefly on the sticky surface means you have stopped several hundred being born.

It’s better to leave leaves on the main stems all the time they are green. They produce energy to swell the fruits. Removing them does not help ripen the fruit, warmth and potash does this.

The final tip is to alter feeding during heatwaves. When it’s hot change the food to one for vegetables which is lower in potash. Continue with high potash feed and the tomatoes will be hard on one side or have unripened lumps in the middle.

This is all a bit serious but you might like to keep this article handy so you can remedy these problems. If you have one I have not included. please get in touch and you might see the answer printed in The News. Have a lovely week.

THIS WEEK’S TOP TIP

You will have certainly noticed that hedges of all types are growing like mad.

Try to cut them before the new growth becomes woody. Regular hedge-cutting takes far less time and is far less tiring too.