Just like humans, most plants need feeding and watering; the method of application and regularity of feeding depend on both the type of plant and the type of plant food.

Plant food contains the nutrients required by plants – once dissolved in water and absorbed by the roots (or sometimes though the leaves), these nutrients are then transported inside the plant to the parts of the plant where they are required.

Nutrients required in major amounts are often referred to as the ‘major nutrients’ and include:

Nitrogen (N): promotes green leafy growth. Without it, growth is slow, leaves may become yellow (chlorotic) and any flowers and fruits will be small.

Phosphorus (P): essential for the development of roots, flowers and shoots. Without it, growth is retarded, leaves may fall prematurely, and any flowers and fruits will be delayed and small.

Potassium (K): supports overall plant health, flower and fruit production. Without it, fruits and seeds are of poor quality, leaves may scorch and roll up.

Other significant nutrients required include magnesium, calcium and sulphur, and nutrients required in small amounts (known as minor nutrients) include iron, manganese and zinc.

Types of Plant Food

General / Multi-Purpose Fertilisers

General multi-purpose fertilisers, sometimes known as compound fertilisers, contain a balance of essential nutrients with different balances having different uses.

A general fertiliser such as Fish, Blood & Bone has an NPK ratio that varies by product brand but is typically around 5-5-6 or 3-9-3, indicating the percentage of nitrogen, phosphorus, and potassium. This multi-purpose fertiliser promotes root development (phosphorus) and overall plant health, foliage, and fruit/flower production (nitrogen and potassium).  

Some multi-purpose fertilisers such as Fish, Blood & Bone are organic while others such as the Miracle-Gro range of fertilisers are inorganic.

The popular Miracle-Gro range of fertilisers includes both controlled release granular fertilisers which allow the nutrients to be released over a period of time, and liquid fertilisers which provide a more instant result.

If you’re growing fruit, vegetables or herbs, it’s essential to check the package wording carefully and only use fertilisers that are suitable for edibles. If in doubt, our friendly team will be happy to advise.

Straight Fertilisers

Straight fertilisers essentially provide primarily one major nutrient, although they may provide other nutrients in much smaller doses. They tend to be less frequently used than other fertilisers but are useful for correcting nutrient deficiencies. Examples include Sulphate of Ammonia for nitrogen, and Sulphate of Potash for potassium. 

Speciality Fertilisers

Speciality fertilisers are formulated for specific types of plants or conditions such as Ericaeous Feed for acid-loving plants such as Rhododendron and Azalea. It’s essential to use ericaceous plant feed for these particular plants as this specialist feed is enriched with the specific nutrients that these plants need to thrive, such as iron, magnesium, and sulphur.

Other popular speciality fertilisers include Olive Tree Feed and Acer Feed which have the benefit of providing all the nutrients required by each of these plants. Tomorite, being high in Potassium, is ideal for tomatoes - as well as many other fruiting and flowering plants including strawberries, peppers, chillies and bedding plants.

When and How to Feed Plants

When and how to apply fertiliser depends on the product you are using as well as the soil and ground conditions. Always follow fertiliser product instructions for the correct method of application, timing and dosage.

As a general rule, apply controlled release fertilisers in early spring before the new growth begins, as that’s when the plant will need most energy.

Liquid feeds are commonly used for outdoor bedding plants as they provide fast acting feed so should be mixed into water and applied during the growing season, from April to September.

Methods of applying fertiliser differ according to the type of plant food and include:

Base dressing – digging in the fertiliser before, or at the time of planting

Top dressing – scattering the fertiliser on the soil surface around the plants, preferably loosely forking or raking into the soil

Liquid feeding – diluting the fertiliser in water and watering into pots or around the plants in the ground

Foliar feeding – some fertilisers such as Maxicrop, once dissolved in water, can be applied as a spray to the leaves of the plant for a fast acting feed. Be sure to spray on dull days to avoid leaf scorch.