A cloning (humidity) dome is a clear plastic cover over a seed or propagation tray. Cuttings have no roots, so they can only replace water lost through their leaves by drawing it up the cut stem; a dome keeps the surrounding air near saturation, typically 80-95% RH, so they lose very little.
In practice
Mist the inside, keep the medium damp rather than wet, and keep the tray warm (about 22-26 °C, 72-79 °F) under gentle light. Most domes have vents. Open them gradually once roots show, usually after a week or so, then remove the lid over a few days so the clones adjust to room humidity. Wipe condensation and remove dead leaves daily; stagnant, saturated air favours mould.
A heat mat under the tray speeds rooting by warming the medium more than the air.
Don't confuse with
- Aeroponic cloner: roots cuttings in mist, often without a dome.
- Hardening off: gradually lowering humidity is a form of it, but the term usually refers to moving plants outdoors.
Cloning is propagating a plant by rooting cuttings from it, producing new plants that are genetically identical to the donor.Relative humidity is the water vapour in air as a percentage of what it could hold at that temperature, so the same RH dries plants differently at different temperatures.Aeroponics grows plants with roots hanging in air inside a dark chamber, wetted by sprayed nutrient solution; low-pressure (LPA) systems use ordinary pumps and spray heads.Hardening off is gradually exposing plants raised indoors or under a dome to harsher conditions, such as sun, wind and lower humidity, so they adapt without shock.A cutting is a piece of shoot, usually a tip with two or three nodes, removed from a plant so it can be rooted into a new, genetically identical plant.
