One of the most exciting moments in tomato growing is when flowers begin to fade and the first little pea-like fruits appear. Each day they grow a little bigger until they reach their mature size when they start to change colour and become ripe tomatoes. They look almost too good to eat! However, temperatures and humidity have to be right for flowers to set fruit. If flowers fail to set, blossom drop is the result and those pretty little blooms wither and break off at the knuckle. To avoid blossom drop, mist and tap plants daily to help release pollen. If the weather is particularly hot and dry, also water around the base of plants to increase humidity.
Watering can be a tricky business when it comes to tomatoes especially if they are grown in containers. However, correct watering can help avoid blossom end rot, which is caused by a lack of calcium when the fruits are swelling and leaves a dark leathery patch on the underside of the tomatoes. The first aim should be to keep the entire root area moist by giving them a thorough watering once a week (especially when the fruits are swelling) and water moderately in between. The reason is that roots are only able to feed and absorb nutrients (including calcium) from areas of soil that are moist. If half of the soil that your plant is growing in is dry, calcium uptake may also be reduced by half.
One way to keep tomato plants healthy, especially when grown in a confined space such as a greenhouse or where they may be planted close together, is to increase aeration. This may be done by removing old, lower leaves below the first truss to improve air circulation.
Opinion about deleafing varies considerably. Some gardeners will leave most leaves on their plants which helps shield tomatoes from direct sunlight. Too much direct sunlight and heat can cause sun scald, greenback and blotchy ripening. Some growers, especially those who grow in greenhouses, remove all leaves below the truss that is producing ripe fruit. This enables plants resourses to be directed into the fruit rather than having to support lots of leaves. Plants grown in greenhouses do not usually have their fruit in direct sunlight for long periods, so avoid the problems of sun scald etc.
When watering, avoid splashing soil up onto the lowest leaves which may transfer soil infections into a plant through the leaves. Splashing water up onto growing fruit may also create ghost spot which is caused by grey mould soil spores and displays small transparent water-like rings. It’s also a good idea to pull off suckers, side shoots and leaf branches by hand rather than cut them because the blades of knives and scissors can spread disease from one plant to another.