Practical 4: Planting and repotting houseplants
Many houseplants can be multiplied by a cutting taken from the tip of the stem. An adult cuts off a stem tip leaving three leaves. Half of each leaf is trimmed so the leaves lose less water. The cutting is put in a glass of water in a warm, bright place that is out of direct sunlight – there it grows roots. Once rooted, expanded clay (so water does not collect) is put in the bottom of a pot and potting mix above it. The mix is 1/3 garden soil, 1/3 peat and 1/3 biohumus. The plant is set in the pot and filled in with the mix; the soil stays 1–2 cm below the rim and covers the root collar. Then it is watered. If a plant stops growing and its lower leaves yellow, the pot has become too small and the plant needs repotting into a larger one. Tap the base of the pot gently and lift the plant out with the soil around its roots, rather than pulling the stem, so the stem is not damaged. A newly planted or repotted plant stays in a cool place for 3–4 days and then moves to a bright spot.
With an adult, root a cutting of one houseplant (for example geranium or tradescantia) in water and plant it in a pot a week later; record the root length every day in your notebook. Safety: only an adult does the cutting; work with biological fertiliser and soil wearing gloves and wash your hands with soap afterwards; some houseplants are poisonous – keep their sap out of your eyes, do not eat leaves or flowers, and keep them away from pets and small children.