How to grow tomatoes

A good yield of tomatoes is subject to careful preparation and fertilisation of the soil in which the crops are to be grown.

Tomatoes are a popular commodity used in everyday recipes and as a complimentary ingredient in most salad dishes.

According to Agribank’s technical advisor for crops and poultry, Hanks Saisai, tomatoes are grown during spring and summer, from September to April, for their fleshy fruits, which are rich in vitamin C.

Saisai says that tomatoes are either determinant or indeterminate plants depending on which cultivar you choose to grow.

Determinant varieties grow into bushes while indeterminate varieties grow over two metres in height and yield about 40 to 70 fruits per plant.

Soil preparation and sowing

Saisai says that tomatoes grow in most soil types.

However, to achieve optimum yields, good soil preparation should be done two to three weeks before planting.

Simple but crucial steps to growing tomatoes include the tilling of soil to a depth of 20 to 30 cm. Incorporating cattle manure before planting may prove essential during the growing season.

Other steps are to plant tomatoes in seed trays containing Hygromix, which is a suitable growth medium for most vegetable seeds at a depth of at least one to two centimeters. Careful irrigation using a watering can in a nursery is recommended, and after 10 to 14 days, germination and emergence of the seedlings should occur.

"Transplanting can be done when the seedlings are about three weeks old and are about 12 to 15 cm tall," Saisai says.

He says the spacing between the rows must be at least 40 cm and that spacing within a row can be at least 20 cm from one tomato to the next tomato growing in the same row.

Caring for the tomatoes

Once the seedlings are transplanted, it is essential for farmers to support the growing tomatoes by staking a stick or any other support structure on which the tomatoes are tied.

"Staking prevents the plant from growing along the ground, keeps tomato fruits off the ground and reduces the risk of diseases. Whilst it is important to water the tomato plants, it is advisable to avoid using sprinkler irrigation when it is very hot as water on the leaves may result in the spread of diseases."

He says that watering can be done daily, but a careful consideration of soil texture may be of great importance.

Sandy soils drain faster, so one is encouraged to irrigate at least once a day. Furthermore, he says that weeding is a must for a tomato grower.

Pruning on certain cultivars of tomatoes is recommended to increase yield potential.

"Additionally, a good fertilisation programme is necessary for successful tomatoes. One can opt to use fertigation, whereby every third week NPK 2:3:2 (37%), which is water soluble, is incorporated into the irrigation system to supply the essential elements, towards the flowering stage."

In addition, farmers are encouraged to use potassium-rich fertilisers such as potassium sulphate via water-soluble mixtures.

Careful watch

Saisai also stressed that scouting throughout the growing season is a must for tomato growers as tomatoes are highly susceptible to diseases and pests.

He says that, depending on location and the prevalence of diseases and pests, a careful spraying programme is a necessity and must be done at least once a month.

Meanwhile, harvesting is expected 90 to 110 days after transplanting, and this can be done by hand.

"The fruits must then be washed and stored in a cool and dry place before being transported to the market."

When transporting them to the respective markets, it is essential to avoid exposing them to direct sunlight as it may negatively affect the shelf life of the fruits.

He concludes that a good investment in high quality seeds of the right variety must be made, and advises growers to follow the instructions on sowing season, sowing depth, and careful irrigation, which are essential for good seedling establishment.