Media is usually kept at 72-77° F while air temperature is maintained at 68-73° F. If bottom heat is not used, air temperature should be maintained between 77 and 80° F. Maintaining air temperatures lower than medium temperatures retards shoot growth while promoting root development. Excessive heat can damage cuttings.
To improve success with rooting of cuttings it is best to maintain media temperatures between 68-77°F; even cold tolerant crops such as pansy, dianthus, osteospermum, petunia, etc. prefer these media temperatures for rooting.
Especially with cuttings, it's often desirable to have a cooler (5 to 10° F) air temperature than root tempera- ture, which allows the roots to grow more quickly than the shoots.
Keep the atmosphere around the cutting warm (not hot), keep the humidity relatively high (>90%), and keep the root zone temperature warm (at about 25°C).
Storage of cuttings
It is best to harvest cuttings in early spring and plant immediately but if this is not possible, cuttings can be stored safely for about 4 months. Store cuttings in a cool, dark, and moist place.
Ideally, the temperature of the medium should be maintained slightly higher (5°F-8°F) than the air so that callus and root growth occur faster than shoot growth. To accomplish this, bottom heat- ing is required. Desirable propaga- tion temperatures are 73°F-77°F for the medium and 68°F-73°F for the air.
If daytime temperatures are above freezing during collection, cuttings should be refrigerated between 31°F to 40°F and 60 to 70 percent humidity. Frozen cuttings can be stored with a small amount of snow to help reduce drying.
Cuttings will root more quickly and reliably in warm rooting mix. Keep your cuttings between 65°F and 75°F, avoiding excessive heat. If your area is too cold, consider a heating mat or cable especially designed for this purpose.
Carefully remove excess leaves to reduce transpiration, so cuttings do not wilt. However, some foliage should be retained to allow photosynthesis to occur. Keep cuttings moist, cool and shaded (collecting in a damp plastic bag is a good idea) until you are ready to put them in a propagation medium.
The Ideal Environment
One must provide: Enough mist without saturating the soil. As much light as possible without raising temperatures. Media and air temperatures that encourage rooting but are not high enough to stress the cuttings.
Give cuttings bright light but not sun. Keep soil moist but not wet. The cuttings should root within three weeks. Admit air gradually to wean the cuttings from their humid environment, then pot singly before outdoor planting.
Cuttings are very delicate and vulnerable so pests, disease, the wrong growing conditions, too much water or too little water can all cause them to fail.
Light provides the energy for callus formation and the subsequent generation of adventitious roots. At the same time, light increases plant temperature and accelerates the drying of leaves, which can quickly dehydrate cuttings. (Under LEDs, this would be less of an issue.)
Using Water
Place your stem cutting in your vessel with enough water to cover the node. The water level will drop due to evaporation, so you should add water every 3-5 days as needed.
From stick to root development (Stages 1-3), propagators sometimes use too little water or moisture, but most often provide too much water, which leads to leaching and waterlogged propagation substrates (Fig. 1), uneven rooting and loss of cuttings due to rot (Fig. 2) or botrytis.
It's important that your water propagated plants receive some light, but bright indirect light with no direct sun is important. They are growing new root systems and are fragile.
Propagating plants from cuttings is an easy and common way to create new houseplants, but it works for many garden plants. In cold-weather zones, you can take clippings of tender annuals and root them indoors to prepare a supply of new plants for garden planting in the spring.
The reason cuttings rot is that over time, the oxygen level of the water drops unless it's moving or oxygen is added. Not only do plants need oxygen in order to grow roots (and, indeed everything else), but the bacteria that cause rotting thrive in low-oxygen environments.
In cold winters or regions hardwood cuttings may root better with protection from a coldframe, cloches or inside a frost free building. Cuttings will need to be protected from rabbits and deer if they are a local problem.
The sooner you can get your cuttings into a more normal environment with air flow and no dome, the better off they'll be. After about a week, remove the dome and monitor your cuttings to see if they begin to wilt. If they do, they're not ready to go dome-less, so try again in 1-2 days.