All plants need nutrients to survive and grow. In the garden they will obtain most of their requirements from the soil but because the area and soil volume in containers is limited and because they are watered more frequently, container-grown plants need regular feeding to thrive and produce the best crops.
The three main nutrients required by plants are nitrogen, phosphorus and potassium. Nitrogen is essential for healthy leaf growth, phosphorus for the development of proper root systems and potassium promotes the production of flowers and fruit.
Plants also need a number of trace elements, the most important of which are manganese and magnesium. Nutrients are present in varying proportions in all fertilizers and foliar feeds and are marked on the label. A balanced fertilizer will contain them in equal proportions.
Growmore, for instance, is a balanced 7:7:7 formula that is widely used. A high potash (potassium) feed is excellent for tomatoes and fruit when the plants are mature and bearing fruit, but all tender vegetables, such as peppers, require high nitrogen feeds when they are growing to help to establish healthy plants.
Permanent plants need fertilizer incorporated in the compost when they are planted. If nutrients are not already present in the compost add bonemeal, Growmore, or fish blood and bone.
Don’t use fish blood and bone or bonemeal if you live in an area where there are urban foxes for they will dig the plant up time and time again. After planting, all plants should be watered with a weak solution of fertilizer.
Most small herbs will not require feeding other than an application of foliar food if the plants appear spindly or distressed. Vegetable crops, on the other hand, need to be fed generously. they require nitrogen-based feeds when growth starts in spring followed by potassium-based fertilizer as the plants reach maturity.
Apply fertilizers in liquid form during the growing season, use a liquid fertilizer or foliar feed. Slow-release granules, however, are invaluable. Add them to the soil at the start of the growing season and one application will serve many plants throughout the year.