How to fill a flower box correctly - instructions in 3 steps

How to fill a flower box correctly - instructions in 3 steps

Step 1: Drainage - effective challenge to waterlogging

If rain and irrigation water in the flower box (€ 13.18 at Amazon *) cannot run off unhindered, your valuable plants have little chance of survival. Root rot is inevitable in waterlogging. You can effectively prevent this problem if you fill a balcony box in the first step with a 3 to 5 cm high drainage made of inorganic material. Pottery shards, expanded clay, (€ 17.50 at Amazon *) pebbles or chippings are well suited.

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If necessary, re-drill the floor holes

In flower boxes (€ 13.18 at Amazon *) made of plastic, the important bottom holes are usually pre-punched. Please punch out these openings with a screwdriver before you fill in the drainage. Only then is it ensured that no waterlogging can build up in the planted balcony box.

Step 2: Spread out breathable fleece

In the second step, lay a thin fleece over it so that the soil on the substrate does not clog the drainage. Use a material that is permeable to water and air and not foil for this purpose.

Step 3: optimize the substrate and fill it in

Please do not impose cheap potting soil on your valuable plants from the discounter. Such substrates usually contain a high proportion of peat, which is questionable from an ecological and horticultural point of view. You should therefore use high-quality, low-peat potting soil in the store, which you can optimize and fill in as follows:

  • Enrich the potting soil to a third with Perlite respiratory flakes or quartz sand
  • Spread the substrate successively with your hands on the drainage and fleece
  • Fill the balcony box no more than halfway with soil

Set the remaining substrate aside. Now plant the potted perennials and flowers. Finally, fill the balcony box with soil up to 2 finger widths below the edge so that no water spills over when watering.


If you are building a wooden balcony box yourself, please cover it with foil first. Only then do you fill the container with the substrate recommended here. A cut open garbage bag can serve as a film. Of course, a thin pond liner is more durable. Cut the film in a cross shape above the holes in the floor so that rain and irrigation water can run off.