Boxwood is a plant that needs a lot of nutrients to stay green. If the fertilizer dosage is low, the plant will grow unsatisfactorily and the leaves will become a pale yellow with yellow edges. A distinction needs to be made between fertilizing plants in the ground and potted plants. Our advice is based on experience in professional nurseries and based on average values. To get an exact advice you need to get a soil analysis. The nature of the soil is key to how much fertilization is needed: loamy and clay soils need less nutrition than sandy soils.
Combined fertilizers include different food components. Nitrogen (N), Phosphate (P) and Potassium (K) are the main ingredients. You can find the formula on the packaging. Magnesium (MgO) is also important because it enhances the green colour of boxwood. When you use seaweed calcium you also provide the necessary trace elements.
For the private gardener there are different systems:
Fertilization using organic fertilizer:
These fertilizers are made from organic raw materials and act gently ( little burn hazard when contact with leaves). On average they work for six to eight weeks. That is why you need to use them a couple of times a year.
- April: 10-15 kg/ 100m²
- mid June: 5-10 kg/ 100m²
- August: 5 kg/ 100m²
These fertilizers do not need to be mixed in with the soil. The extra magnesium in this fertilizer is responsible for a nice green colour. Example formula: 7-5-7 +2MgO
Fertilization using coated fertilizers:
These granules are coated so the nutrients are released slowly. There is no danger of injuring plant tissues. These fertilizers are eco-friendly because only a very small amount of the nutrients seeps to the ground water. They work for five to six months, depending on the formula. Using it one time a year will be sufficient in most cases. In some cases, a small amount of fertilization can be applied in August.
- March/ April: 7 kg/ 100m²
- If necessary in August: 3 kg/ 100m²
Example: Everris Agroblen 15-8-16 + 5%MgO
TIP: In gardens with a lot of hedges or large trees you need to up the dosage. Feeding can be done when the weather is dry, preferably after a shower or a downpour afterwards is ideal.
Fertilization in pots
Professional nurseries mostly use the coated fertilizer Osmocote for potted plants. Because of the special resin coating the nutrients are released gradually so the plants have sufficient nutrients during the entire growing season. The growth will be even. It works approximately for six months, depending on the chosen formula, so one feed a year is enough. There are practically no nutrients that are washed away to the ground water, which means the procedure is efficient and eco-friendly. March/ April: 30 grams per 10 litres (loose grains)or four tablets of 7.5 grams/ 10 litres (tablets)