This week we are focusing on tomatoes as they are one of the top vegetables grown in our gardens.

These are one of my favourite vegetables to grow, ripe tomato fruits come in red, yellow, orange, pink or white and round, flat, plum or pear shaped.

Some may even develop unusual protuberances. Size varies from a 2-3cm diameter in the small cherry tomatoes to approximately 10cm in say beefsteak. All can be eaten raw or cooked.

Tomatoes grow best in a full sun position but sheltered from the wind. They grow best at 21-24˚C and do not thrive at temperatures below 10˚C or above 27˚C and do not tolerate frost.


The plants perform best if they are rotated with other vegetable crops to prevent a build-up of soil borne pests and diseases. If the soil is boosted with regular applications of compost and fertiliser then rotation may not be necessary. Tomatoes are also grown very successfully in containers and this is another popular option.

When planting out into garden beds the soil should first be prepared by working in plenty of mushroom compost, 'Natural Bark Poultry Compost' or other products such as 'Tui Tomato Mix', 'Tui Sheep Pellets'. Mix in the soil at least 30cm deep since tomatoes develop a deep root system in this range and are gross feeders.

Work in tomato fertiliser before planting; tomatoes need high levels of phosphate, but low levels of nitrogen. For tomato plants being grown in the garden I recommend 'Tui Tomato Fertiliser' and for plants being grown in pots I recommend 'Manutec Tomato Tablets', these are applied by pushing them below the soil surface on each side of the plant and will release food for up to 8 weeks that I have found to be very good.

Tomato Olgas Round Golden Chicken Egg
This variety has ranked highly in research by the NZ Heritage Food Crops Research Trust looking for tomatoes with high health properties. 'Olga' has very high lycopene levels which are properties that aid in cancer prevention. The golden coloured, rounded fruit is of medium size approximately 6cm in diameter and weighing in at 110-170gms.

It has great flavour and can be used fresh in salads, on sandwiches or for cooking.

Routine Care
All tomato types should be watered and mulched thoroughly once the soil is warm. Plants in containers need more frequent watering and supplementary tomato fertiliser to complement the loss of leached out nutrients, the additional liquid feed of 'Yates Thrive for Tomatoes' or 'Ican Fast Food' is recommended. Be careful not to over water or overfeed as this may reduce flavour. Also, avoid watering the foliage as this may lead to fungus infection, apply water directly to the soil over the root area or use a watering can, soaker hose, micro irrigation drippers or similar.

In mid to late summer some like to remove the growing tip (terminal shoot) to three leaves above a fruit truss to discourage further height and encourage the remaining fruit to ripen. Laterals should be removed about once a week, beginning about 3 weeks after planting. They readily bend and break off from a healthy plant.

Carry out this task when the plants are dry as there is less risk of disease infection. The same applies to unwanted foliage.

As leaves grow older they shade one another and the fruit. Removing some improves air circulation and further reduces the risk of disease and allows more sunlight to ripen the fruit. Grafted tomatoes can be grown without the need to have any laterals removed, as the more vigorous root system will support the larger plant. Multiple stakes or other type of support frame will be necessary so the plant doesn't collapse as the fruit forms.

Pests and Diseases
Some pests and diseases of tomatoes are; damping off of seedlings, mites, whiteflies, tomato caterpillars, bronze wilt, nematodes, fruit flies, tomato psyllid and tomato blight.

Tomatoes under cover are susceptible to whiteflies, mosaic virus, grey mould (Botrytis), tomato leaf mould, magnesium deficiency, boron deficiency, stem rots and root rots and blossom end rot. Many of the above mentioned problems are rare and can be controlled readily if observed.

The two most common problems in Whanganui are blight and tomato (also potato) psyllid. Blight is a fungal problem and can be prevented and controlled with the use of biogrow certified organic 'Growsafe Freeflo Copper' or 'Yates Tomato Dust'. The tomato/ potato psyllid is readily controlled by the use of bee friendly 'Yates Mavrik'.

Come and see us at the garden centre if you encounter any of these problems, we can advise on the best means of control.

Have a good week!

Gareth Carter is General Manager of Springvale Garden Centre