Juurennus

Juurennus is a horticultural propagation method in which roots are induced to form on plant cuttings so that they can become independent plants. It is used to reproduce a plant genetically identical to the parent and can occur naturally when a stem or runner develops roots where it contacts soil, but in cultivation it is guided by selecting suitable material, substrates, and environmental conditions.

Cuttings and preparation: The material for juurennus typically comes from healthy parent plants. Cuttings are taken at appropriate lengths (for example, 4–15 cm for many species) and may be taken from softwood, semi-ripe, or hardwood stages depending on the plant. Leaves on lower portions are often removed to reduce water loss, and the cut ends may be treated with rooting hormone to stimulate root formation.

Medium and environment: Cuttings are placed in a well-draining rooting medium, such as a blend of peat, perlite, or sand, or kept in water for hydroponic rooting. Key environmental factors are adequate humidity, moderate light, and appropriate temperatures, commonly around 20–25°C for many species. Some woody cuttings benefit from bottom heat to encourage root initiation. High humidity helps prevent desiccation during the rooting period.

Timing, success, and care: Rooting times vary widely by species and method, ranging from a couple of weeks to several months. Successful juurennus depends on avoiding excess moisture that causes rot, providing sufficient air for roots, and protecting new cuttings from pests and temperature stress. After roots form, cuttings are gradually acclimatized to normal growing conditions and transferred to larger pots or the field.

Applications and relevance: Juurennus is widely used in horticulture and forestry to propagate ornamentals, fruit trees, and other valuable plants without genetic variation. It complements other vegetative propagation methods and is chosen based on species, desired speed, and available facilities.