Plant Fertiliser

The best time to fertilise plants is at the start of their growth period — usually in spring, as the weather begins to warm up after winter. For best results, trees generally like be fertilised in early spring, shrubs in spring and summer and lawn in mid to late spring.

Some plants such as grasses may have a second growth period during the summer. Adding fertiliser to the soil when you plant flowers and vegetables can help to maximise their growth.

The frequency of fertilisation will depend on the product you use and the particular plant — different plants have growth periods at varying times.

You can ask an All Green horticulturalist for specific advice on fertilising your plant species to ensure you get it right.

The best method of application depends on the type of fertiliser that you are using. Pellet fertiliser can broadly cover a large area such as a lawn or new garden bed using a drop spreader or hand rotary device to scatter the product. Granular or pellet fertilisers can also be applied by hand to individual plants around the plant base or in a strip parallel to the planting row for vegetables.

Water-soluble fertilisers need to be applied more frequently and provide immediate nutrition to plants. Application plant base or foliage using a watering can or hose attachment provides nutrients directly to the plant. Foliage application encourages rapid absorption of trace elements such as iron.

Most plant fertilisers contain the three essential elements required for plant growth: nitrogen, phosphorous and potassium. The amount of each should appear on the packaging of the fertiliser. Different types of plants prefer different nutrient ratios, so if you aren't sure, ask a horticulturalist for advice.

Many fertilisers also contain trace elements that plants need to grow well. Fertilisers may also contain inert materials that contribute to the consistency or shape of the fertiliser product.

Organic fertilisers can be formulated or may consist of composts or manures. These may be bulkier but are more likely to be free from any synthetic chemicals. Check the label and ask for advice if you are unsure which organic fertiliser is suitable for your garden.

The best fertiliser will depend on the plant species and how frequently you want to fertilise. Flowering plants like roses grow best with frequent fertilisation using a soluble fertiliser during the blooming season.

Granular fertiliser is suitable for most established plants. It is released slowly into the soil, so one application at the beginning of spring ensures the established trees and shrubs have the nutrients to grow well through the springtime.

When planting bulbs at the end of autumn, a bone meal fertiliser can encourage healthy growth. If you aren't sure which fertiliser will be best, ask for advice from the friendly staff at All Green.