What all the plants have in common is that, in addition to a range of trace elements such as copper, sulphur, magnesium and others, they all need four main nutrients: Nitrogen - a growth driver and the main component of proteins but also an important element of chlorophyll; magnesium - a key element of this chlorophyll; phosphorous - mainly to promote flowering; and potassium to firm up the tissue and ripen the fruit.
For balcony and pot plants I use a mineral soil such as a potting mix. The stored fertiliser can be easily raked through and is not washed out by frequent plant watering. The fertiliser reserve of a high-quality flower soil, normally added by the manufacturer, usually lasts for around six weeks. At this point at the latest, you need to add more fertiliser. I therefore add long-term fertiliser to the soil during planting - 2-3 grammes per litre of soil. This is how I provide basic food for my plants up until August/September. I also add a small dose of liquid feed each week - 0.1 to 0.2 parts per thousand - when watering (i.e. 10 to 20 ml of liquid feed for a full 10 l watering can). Again: Follow the manufacturer's instructions on the fertiliser packaging!
In shrub gardens, the extent of fertilising measures mainly depends on the size of the mass formed by the leaves and flowers of the plants. I only fertilise rockery shrubs here and there with a handful of hornmeal or a little compost (barely a litre per square metre). Strongly growing bed shrubs can be given around 50 grammes of compound fertiliser per square metre in spring (around March/April). Alternatively, you can give them around three litres of compost per square metre. Weaker growing shrubs only need 30 grammes or 1.5 litres. In mid-June you can feed them again with a second, slightly reduced amount.
In vegetable gardens, the extent of fertilising measures mainly depends on the type of plant, since because vegetable plants can be divided into strong consumers, including cabbage, medium consumers such as tomatoes and weak consumers such as lettuce. Here are some individual fertilising recommendations:
Weak consumers: Add 1 to 2 litres of compost per square metre and, if necessary, additional nitrogen (approx. 70 grammes of hornmeal per square metre) and potassium (approx. 35 grammes of potassium magnesium fertiliser per square metre).
Medium consumers: Add 2 to 4 litres of compost per square metre and, if necessary, additional nitrogen (approx. 120 grammes of hornmeal per square metre) and potassium (approx. 70 grammes of potassium magnesium fertiliser per square metre).
Strong consumers: Add 4 to 6 litres of compost per square metre and, if necessary, additional nitrogen (approx. 150 grammes of hornmeal per square metre) and potassium (approx. 100 grammes of potassium magnesium fertiliser per square metre).
To fertilise trees, you first have to differentiate between deciduous trees and evergreens. Their annual growth cycles are rather different, which is why they need fertilisers at slightly different times.