Applying Fertilizer
Organic and inorganic fertilizers may be applied to plants and lawns by broadcasting or by simply placing around individual plants. There are also liquid fertilizers available that may be applied to the soil surface or directly onto leaves. This article looks at applying fertilizer to plants; our Lawns section discusses the application of fertilizer to turf.
Always make sure that you read the manufacturers' recommended application rates carefully; too much fertilizer could damage your plants.
Always use gloves when working with fertilizers, and take care not to breathe in any of the vapour or dust that comes from them.
Placement Fertilization
An efficient and economical method of feeding specific plants is to scatter fertilizer evenly around the base, making sure that you keep it away from the stems and leaves. The plant roots will spread quickly through the fertilized area.
Broadcast Fertilization
Broadcast fertilization involves scattering the fertilizer over the whole soil surface. This benefits the greatest area of soil and minimises the risk of plant injury from overfeeding.
Mark out your plot into square metres (or square yards) using garden canes. Fill a bucket or large container with the recommended amount of fertilizer for the entire plot. Measure out the right amount for each of your squares marking where this comes to on a small pot. Scatter this evenly by shaking it over each section of your plot, keeping the fertilizer clear of any plant leaves and stems to prevent scorching. Continue until you have covered each section, then lightly dig or rake the fertilizer into the top layer of the soil. Digging will help the soil take in immobile nutrients such as phosphate.
Liquid Fertilizers
Soil uptake of granular fertilizers may be poor in dry weather, and so in these conditions a liquid fertilizer should be used. However, you should avoid using them when rain is forecast as they will be easily washed away.
Foliar Fertilizers
Foliar fertilizers should be applied directly to the leaf surfaces of plants and is a useful and effective method for correcting mineral deficiencies. Research has shown that it is 4-30 times more effective to feed a plant through its leaves and there is no risk of ground water contamination.
The best time to foliar feed is 7-10 am or after 5 pm when it is cool and the plant's stomata (the small openings on the leaves) are closed. Avoid feeding the plant if the temperature is higher than 25° C (77° F) as the spray droplets will evaporate before the plant has time to absorb them.