One of the most grown foods in a London garden are tomatoes. When home grown, they are delicious and plentiful if cared for correctly.
When to fertilise ‐ The best time to fertilise is before the tomatoes are even planted. Fortifying the soil beneath the plants before the plants are added to it means that the nutrients are already there, ready to be unlocked, and run no risk of 'burning' or other adverse effects from fertilisation whilst the plant is growing.
If your plants are already growing, then use small amounts of fertilisers or use organics that do not burn, such as compost and light manures. A good rule of thumb is to side dress every month with a low nitrogen fertiliser. The best time of day to use most fertilisers is in the evening, when the sun is waning, or after watering/rain. Compost/light manure, such as chicken leavings or vermin‐compost can be used at any time. It should be spread lightly over the ground around the plants. Do not dig it in or disturb the soil as this can harm the tomato’s roots.
How to fertilise ‐ If the plants are not in the soil, then mix the compost in well with the upper layer. If not, spreading it over the top of the soil and allowing the rain and maybe your own watering to push it into the soil. If you compost/manure your soil in the week or two before planting and again after harvest before winter, within a couple of years you’ll have some of the best garden soil on the planet. Keeping up this regime twice yearly means there is no need for artificial spraying or fertilising without sacrificing yields.
Compost ‐ Compost is good for tomatoes at any time you want to add it. Quality compost, either made yourself or purchased, can be spread on the ground around the plants to add nutrition to the soil.
Compost tea ‐ Compost tea is probably the best way to inject nutrients directly into the plants without cutting into the soil. It can be poured directly onto the base of the plant to soak into the roots. Most compost tea is nitrogen and potassium rich as a function of how it’s made. Manure tea is also a good substitute if compost is not available for brewing.