Nutrients for plants

Plants need nutrients in order to grow. While they need larger amounts of macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium and sulfur), small amounts of micronutrients are sufficient. Plants in containers need to be watered and fertilized more often than their garden counterparts because they have less root space available. Also, the substrate of container plants contains fewer soil organisms, so decomposition of organic material generally takes slightly longer.

„Substrate“: Usually industrially produced mixture of various mineral and organic materials used for growing and cultivating plants.

Which nutrients do my plants need to grow?

How many nutrients does my plant need?

High nutrient-demanding plants

Usually develop lots of fruits or produce large leaf masses
Need a lot of nutrients, which is balanced with fertilizer applied every 2-3 weeks during the growing period
Soil is also enriched with nutrients before planting
E.g. tomato, potato, cucumber, cabbage, zucchini

Medium nutrient-demanding plants

Have a medium nutrient demand
Soil is prepared similarly to the one of high nutrient-demanding plants
Fertilizer applications during the growing period do not need to be as regular but rather are based on need
E.g. kohlrabi garlic, onions, carrots

Low nutrient-demanding plants

Get by with few nutrients
Usually do not require additional fertilizer
E.g. herbs, arugula, peas, beans

What are the types of fertilizers?

Organic fertilizers

Organic fertilizers come from plants or animals and contain nutrients in bound form. Before the nutrients are available to the plants, the organic structures in which the nutrients are embedded must be decomposed by microorganisms. Therefore, organic fertilizers have a slow and long-lasting effect. For decomposition, the microorganisms need nitrogen. Therefore, you should pay attention to the C/N ratio of your organic fertilizer. Generally, the finer the organic components, the faster the decomposition. Organic fertilizers contain a variety of macro- and micronutrients and are good compound fertilizers. The nutrient concentration is lower than for mineral fertilizers, which is why overfertilization does not have such disastrous consequences. The use of organic fertilizers also does not cause soil salinization. On the contrary, organic fertilizers promote soil life and humus formation, which improves soil structure.

„C/N ratio“: Ratio of carbon (C) to nitrogen (N) in an organic mass. The closer the C/N ratio, the more nitrogen is present compared to carbon, and the faster decomposition proceeds. A good C/N ratio is 1:25.

Mineral fertilizers

With mineral fertilizers, the plant nutrients are present as salts that dissolve quickly in soil water and are immediately available to the plants. Mineral fertilizers bypass the natural cycle of nutrient recycling, which can easily cause a chemical imbalance and a pH change in the soil. Increasing salinity also inhibits the activity of many soil organisms. Too high concentrations of mineral salts can cause leaf and root burns! Generally, a distinction can be made between natural mineral fertilizers (e.g. wood ash or potash magnesia) and artificial fertilizers. The latter do not occur in nature, rather they are produced chemically.

Which fertilizers are at my disposal?

Basic dressing (or long-term fertilization)

Basic dressing is the application of plant nutrients before sowing or planting. It is advantageous to use compound fertilizers, or several fertilizers at once, to provide the plant with all the necessary nutrients. The following natural and commercial fertilizers are suitable for basic dresssing:

Nitrogen N %

Phosphate P2O5 %

Potassium K2O %

Compost

1-1,75

0,45-0,9

0,75-1,5

Compost

Nitrogen N %

1-1,75

Phosphate P2O5 %

0,45-0,9

Potassium K2O %

0,75-1,5

Coffee grounds

2,1

0,3

Tea grounds

4,2

0,6

0,4

Dung

Nitrogen N %

0,4-2,4

Phosphate P2O5 %

0,2-1,5

Potassium K2O %

0,4-1,7

Chicken manure

1,5-1,7

1,2-1,5

0,7-1,7

Rabbit manure

0,8-2,4

0,3-1,4

0,6-0,7

Horse manure

0,4-0,7

0,3-0,4

0,4-0,6

Cattle manure

0,4-0,5

0,2-0,3

0,5-0,8

Guano

11-12

2-2,5

Guano

Nitrogen N %

Phosphate P2O5 %

11-12

Potassium K2O %

2-2,5

Sheep wool

Nitrogen N %

10-12

Phosphate P2O5 %

0,1-0,3

Potassium K2O %

4-7

Sheep wool

10-12

0,1-0,3

4-7

Horn shavings

10-14

2-5

—

Horn shavings

Nitrogen N %

10-14

Phosphate P2O5 %

2-5

Potassium K2O %

—

Blood meal

Nitrogen N %

Phosphate P2O5 %

0,8

Potassium K2O %

—

Blood meal

0,8

—

Bone meal

2-4

21-30

0,2

Bone meal

Nitrogen N %

2-4

Phosphate P2O5 %

21-30

Potassium K2O %

0,2

Clover fertilizer

Nitrogen N %

3,5

Phosphate P2O5 %

0,8

Potassium K2O %

3,4

Kleedünger

3,5

0,8

3,4

Wood ash

—

1,5-4

6-10

Wood ash

Nitrogen N %

—

Phosphate P2O5 %

1,5-4

Potassium K2O %

6-10

Kalimagnesia

Nitrogen N %

—

Phosphate P2O5 %

—

Potassium K2O %

25-30

Kalimagnesia

—

25-30

Sheep wool pellets strongly swell and can thus absorb 3.5 times their own weight in water and store it sustainably.

Top dressing (or short-term fertilization)

Top dressing refers to the continuous supply of nutrients to the plants during the growing season. In addition to the liquid fertilizers listed below, which are particularly suitable for high nutrient-demanding container plants, you can also give the plants smaller nutrient boosts in between. Compost extract, worm tea or bokashi, for example, can be used for this. You can also water with cooking water from eggs and potatoes (without salt!) or with water which you have washed vegetables or fruit with. It contains micronutrients that benefit the plant.

Nitrogen N %

Phosphate P2O5 %

Potassium K2O %

Nettles

Nitrogen N %

Phosphate P2O5 %

Potassium K2O %

1-3

Nettles

1-3

Comfrey

2-3

3-4

Comfrey

Nitrogen N %

2-3

Phosphate P2O5 %

Potassium K2O %

3-4

Vinasse

Nitrogen N %

4-4,5

Phosphate P2O5 %

0,3-0,5

Potassium K2O %

5-7

Vinasse

4-4,5

0,3-0,5

5-7

Tomato fertilizer

3-4

1-1,5

4-5,5

Tomato fertilizer

Nitrogen N %

3-4

Phosphate P2O5 %

0,3-0,51-1,5

Potassium K2O %

4-5,5

„Molasses“: Viscous syrup obtained as a waste product during sugar beet production.

How to make slurry?

Half fill a plastic container (10-15 l capacity) with coarsely chopped nettle or comfrey leaves (1-1.5 kg fresh or 150-200g dried) and pour water over them so that they are well covered.
Stir the mixture well with a stick.
Add (primary) rock dust to bind odors.
Cover the container, but do not seal it airtight.
Stir every 1-2 days and re-spread new (primal) rock flour.
Slurry is ready after 2-3 weeks when it is dark in color and no longer foams.
Strain the liquid manure through a sieve or cloth.
Dilute it 1:10 with water for fertilizing (1:20 for more sensitive plants and young plants). As a general rule, the longer the slurry ferments, the higher the dilution should be.