Conifers and deciduous trees have very different nutrient requirements. The reason is that their annual growth cycle is different. They therefore need their main supply of fertiliser at different times.
Conifers initially require nutrients during the month of May, and a second, higher dosage from the end of July to the end of August. The cones and seeds form during this time. Distribution of the fertiliser quantities for conifers over the two fertiliser phases is therefore 35/65.
The concrete quantity of fertiliser is at first based on the nutrients already available in the earth. Garden soils tend to be rather over-fertilised. It is recommended to take a soil sample approximately every five years in order to determine the actual nutrient requirement of the garden plants. The actual fertiliser requirement of the conifers depends on their size. In the case of small conifers, approx. 30 grammes of compound fertiliser per square metre and year is sufficient. For maintenance fertilisation of trees and large bushes under the conifers, on the other hand, approx. 50-70 grammes of compound fertiliser per square metre and year is required.
To complete the information: deciduous shrubs mainly require their nutrients from early to mid-June and, for a second growth spurt, approximately from mid-July to mid-August. Therefore, do not fertilise after this. Deciduous shrubs should be given the first dosage of fertiliser (approx. 55 per cent of their annual requirement) in April, the second (45 per cent) in June. With fruit trees and roses, the figures change slightly. The dosage here is 50/50 or 60/40. As with the conifers, you can adjust the quantities. Only in the case of fruit trees, roses and rhododendrons, due to the higher nutrient requirement, you can go to the upper limit and use 100 grammes of fertiliser in the two periods mentioned.
Tip: Note that, for both conifers and deciduous shrubs, the nutrients must be available to the roots at the specified times. This means that if you use organic fertiliser (for example compost, horn shavings or granulated cow manure), you must allow for a run-up time – depending on soil moisture and heat – of up to three or four weeks for plant-available degradation of the dispensed fertiliser