Fertilising a hedge: how to give your hedge plants the best care

Overview: Fertilising a hedge

• You should fertilise your hedge regularly to ensure that the plants receive an optimal supply of all the important nutrients.

• A soil analysis will provide information on the specific nutrient requirements of your hedge.

• Hedge fertilisers should be applied no later than the end of August so that the plants can prepare for the winter.
  

Do I have to fertilise my hedge?

A hedge consists of densely planted woody plants that require nutrients such as nitrogen (N), phosphorus (P) and potassium (K). Supplying the right nutrients will ensure healthy growth for your hedge plants as well as lush blooms for flowering varieties. You should therefore fertilise your hedge regardless of its age and also support seedlings during growth. 

Optimal nutrient supply will also help to fill gaps in hedges more quickly. You can tell whether you need to fertilise your hedge by looking closely at the plants; at a minimum, you should do this when you are trimming your hedge. For example, light-coloured leaves towards the bottom of the plant in particular, indicate a lack of nitrogen, which can be remedied with an appropriate hedge fertiliser.

Exceptional case: fertilising a hedge in autumn

You should generally avoid fertilising your hedge in autumn. This is because when summer is over, plants gradually begin to prepare for the coming winter. Fertilising them with nitrogen-rich hedge fertiliser at this time would lead to weak new growth, which could be damaged by frost in the winter. Newly-planted hedges are an exception, as you can dig in bonemeal around young plants in the autumn to stimulate long-term growth.

How often should I fertilise my hedge?

Hedges are normally not very demanding. Therefore, it is sufficient to fertilise your hedge twice a year. We recommend first applying a long-term fertiliser in the spring. This will supply your hedge abundantly with all of the important nutrients for around three months.

You should then fertilise for a second time in July. A fertiliser with a more short-term effect is practical for this second fertilisation, as it will only remain active until the end of August at the latest. This ensures that your hedges can prepare properly for the winter.

If you notice a nutrient deficiency during the growing phase despite having fertilised your hedge, you can re-fertilise it if necessary. However, you should always check how long the fertiliser you are using remains active so that your hedge can slow down to prepare for winter in good time.

Which fertiliser is best for a hedge?

Organic long-term fertilisers are best for hedges at the start of the new gardening season. These hedge fertilisers consist of plant and animal waste substances that are not harmful to the environment.

STIHL expert tip: use a mineral-organic fertiliser for re-fertilisation. The mix will supply the necessary nutrients to topiary hedges in particular in July without continuing to have an effect too long into autumn.

These nutrients are important for fertilising your hedge

Hedge plants generally require three basic nutrients: nitrogen, phosphorous and potassium. Nitrogen is responsible for long-term growth and is an important component of proteins in chlorophyll. The substance is very mobile within the plant. If a shortage of nitrogen arises, the upper leaves will draw the nitrogen upward, resulting in light-green leaves towards the bottom of the plant. You can correct a nitrogen deficiency by fertilising your hedge with a fertiliser that contains nitrogen. Bonemeal is ideal for this purpose.

Phosphorus gives hedge plants the energy they need to produce flowers and seeds. You should therefore ensure that your hedge has a healthy supply of phosphorus so that it can look its best when blooming.

Potassium is responsible for the water balance within the plant. When water transport is optimal, the plant produces firm tissue, which in turn makes it resistant to pests, hedge diseases and frost.

A soil analysis will help you find out which nutrients you should use to fertilise your hedge. This will help prevent unnecessary stress on the soil and will tell you exactly which nutrients your hedge needs.

Which fertiliser is best for which hedge?

Organic long-term fertilisers are generally very good for fertilising hedges. However, the ideal fertiliser may differ depending on the type of hedge you have.

For example, Blaukorn is relatively rich in content and has a visible immediate effect, but does not work for long. If you fertilise your hedge with Blaukorn you should avoid using organic fertilisers afterwards, as the plants will not be able to absorb the nutrients.

Applying Epsom salts ensures a rich colour in conifers such as thuja. The mineral salt is also fast-acting and loses its potency after a short time. The best time to fertilise a hedge with Epsom salts is in spring.

Finished compost is an excellent fertiliser for privet hedges. These undemanding plants only need a single application of compost in spring to be well-supplied all year round.

Compost mixed with bonemeal is the ideal hedge fertiliser for beech trees and cherry laurel. You can use this mix to fertilise your hedge in the spring and you will not need to fertilise it again in July.

Specialised conifer fertiliser can be applied between March and May as required. It is ideal for thuja and for yew trees.

STIHL expert tip: you should ensure good soil contact when fertilising your hedge. Work any hedge fertiliser thoroughly into the soil so that the nutrients can get to the roots of your hedge plants with ease. You can usually do this simply by raking the fertiliser into the soil after application.