Our tomatoes are covered in whitefly, the fruit and leaves are becoming sticky and black and we have found nothing to control the attack, what can you suggest?

A severe attack will be very difficult to control.

Try spraying every two or three days with a fatty acid insecticide.

The eggs and nymphs will not be so easy to control it could take several weeks to reduce the infestation to acceptable levels.

When you clear out the tomatoes, spray the inside of the greenhouse well with an insecticide to reduce the chances of spreading the whitefly further.

Wash the structure down with Jeyes Fluid or similar during the winter.


What was the cause of our greenhouse tomatoes ripening to a mixture of yellow and red colour, and where under the yellow areas, the flesh was rather hard.

The condition is known as blotchy ripening, and is generally more severe in hot, sunny weather.

High temperatures, high light intensity and also high nitrogen and low potash all seem to encourage the problem.

To reduce damage, shade the greenhouse glass in the late spring and ventilate as much as conditions will allow.

Once the flowers set and embryo fruit appear, feed the plants with a high potash tomato fertiliser.


My outdoor cherry tomatoes all suffered from splitting skins,that left scars around the sides, what causes this ?

The splitting will have been caused by heavy rainfall or watering occurring after a period of drought.

Under dry conditions tomato skins become hardened and are then unable to cope with any rapid expansion of the fruits after sudden uptake of water.

Prevent this in future years by regular, steady watering during any dry periods.


How do you prepare growing bags for planting?

Keep the bags under glass/indoors for a couple of days prior to planting to warm up the compost.

Loosen the compost by plumping up each bag as you would a pillow.

Alternatively, before opening fold the bag in half, allowing equal amounts of compost to filter into either side of the fold.

Cut along the fold, roll down the surplus plastic to form a hem, you have now effectively formed two pots of compost.

Cut three drainage slits along each side of the bag about 12mm (½”) above ground level to prevent the bags (pots) becoming waterlogged.


My tomato plants seem to flower OK but the fruit does not form, what is causing this?

Poor pollination!

This is caused by too high temperatures, dry compost or lack of humidity.

Keep the greenhouse well ventilated, water regularly and mist the flowers.

Shake the trusses gently, preferably around mid-day to distribute the pollen.


The leaves on my tomato plants are twisting and curling up,what is causing this?

This is due to large differences between day and night time temperatures, and is nothing to worry about.


My tomatoes are splitting, why?

This usually happens because the compost has been allowed to dry out, causing the skin to harden before the fruit has finished expanding.

When the fruit starts to take up water after watering, the skin cannot expand as the fruit swells, so it splits.

Always keep the compost moist to avoid this problem.

On hot bright days, give at least 2 litres (3pints) of water per plant per day, on dull days, your plants may need less, say a third to half of this quantity.


My tomatoes are beginning to rot at the base of the fruit, what is causing this?

This is Blossom end rot sometimes caused by a deficiency of calcium, and/or irregular watering.

There is no cure, remove fruit from plant and destroy it (do not compost it)

Mist the plants each morning or dampen down the greenhouse paths to maintain humidity.

On hot bright days, give at least 2 litres (3pints) of water per plant per day, on dull days, your plants may need less, say a third to half of this quantity.

To prevent this in future, choose non-susceptible varieties bred to reduce this problem.


When and how often do I feed my tomatoes?

Commence feeding when the first truss has set, i.e. when you can see that tiny green tomatoes have formed.

Feed with a proprietary Tomato food mixed to the manufacturers specification once a week after first truss has set, twice a week after second truss has set, and at every watering after the third truss has set.


My tomatoes are not ripening evenly, and the tops stay green, what is my problem?

This is known as Greenback and is caused by too much direct sunlight or high temperatures and possibly not enough potash.

Some of the older varieties are more susceptible to this than the newer varieties, many of which have been bred to overcome this problem.

There is no cure for affected fruit, but the fruit is still edible providing you cut away the green area.

To protect the fruit, increase the shading and ventilation in the greenhouse.

Feed with a high-potash feed and water regularly, and more frequently in hot weather.


The leaves of my tomato plants are turning light brown/yellow, what is the problem?

This is caused by the lack of magnesium.

This is often the result of waterlogging at the roots, disease and/or high concentrations of salts in the compost.

The deficiency can be made worse by normal feeding with a high-potash fertiliser.

To control it spray the leaves with magnesium sulphate (Epsom salts).

Use 20gms (¾ oz) per litre of water (3oz per gal)

To ensure the liquid stays on the leaves add a wetting agent e.g. a spot of washing up liquid.

Alternatively, use a tomato feed containing magnesium.


I have a lot of green tomatoes at the end of the season what can I do with them?

You could try making Chutney with them, or try and ripen them indoors.

Place tomatoes in a tray lined with paper and place in a dark, reasonably warm, dry spot in the house, e.g. the airing cupboard.

It is said that by placing an apple in the tray this will speed up ripening due to the ethylene gas given off by the apple.

Check tomatoes regularly and remove any that have ripened, or any that may have started to rot.


Top of the Page