Several cuttings may be placed together in one container. Be sure to add fresh water as needed until the cuttings are fully rooted. Rooting will generally occur in 3-4 weeks but some plants will take longer. When the roots are 1-2 inches long or longer the cutting is ready to be potted up.
(Many plants will root successfully from cuttings without the use of rooting hormone, but using hormone can speed up the process, and it might be essential for some hard-to-propagate plants.) If you are using a powdered hormone, it helps to moisten the stem before rolling it in the powder.
Some plants will root in water, but cuttings will develop a better root system when rooted in a soil-less potting mix. Sand or perlite can also be used, especially for cuttings that need good drainage and may rot if kept too wet.
After two or three weeks, check to see if roots have formed by working your hand under the cutting and gently lifting (Figure 3). If no roots have formed, or if they are very small, firm the cutting back into the mix, rebag, and check for roots again in one to two weeks.
Too much or too frequent application of mist / fog keeps the growing medium saturated, excess water will flow from the bottom of the trays and rooting will be delayed. Applying mist / fog too infrequently will increase transpiration from the leaves and cuttings will lose turgidity and could die from drying out.
Try to wait until at least 50% of the cuttings have good rooting before potting them up; however, for some hard-to-root species, you may be lucky with only 10% to 20% success.
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.
Technically, you can transfer your cuttings to soil at any time. In fact, you can actually propagate directly into soil, however, it's much harder to do within your home. When you propagate in soil, you have to keep a good balance of soil moisture, air flow, and humidity.
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.
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.
Managing photosynthetic light during callusing is a balancing act. Enough light should be provided so cuttings can photosynthesize, producing the carbohydrates required to sustain the cutting as well as promote new growth, including root development.
Plant cuttings mistakes can range from using dirty tools to potting up your cuttings in the incorrect potting soil. Too much harsh sun, too much or not enough water, and using offcuts from plants that are sickly or flowering can also put your cuttings at risk.
Roots need air in order to grow. You should try and change the water with fresh tap water every 2-3 days or so for best results because oxygen in the water will be depleted.
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.
The basic principle behind applying mist to vegetative cuttings is simple. Without roots, cuttings cannot adequately replace the water lost to the environment due to evaporation and transpiration mainly. To aid them along the beginning of their life journey we must replace this water loss with water applications.
Erler prefers planting leaf cuttings in a standard indoor soil mix as soon as you cut them, because she says they can easily rot in water. If you're planting an unrooted cutting, she recommends watering the soil and using your finger or a pencil to create a small hole. Gently place the cutting inside.
Cover the pot with a clear plastic bag held in place with a rubber band or similar around the pot, to keep the compost moist. Place the pot on a well-lit position indoors, but out of direct sunlight. Keep compost moist and your cuttings should root in six to eight weeks.
Maintain high humidity by covering the pot with a bottomless milk jug or by placing the pot into a clear plastic bag. Cuttings can also be placed in plastic trays covered with clear plastic stretched over a wire frame (Figure 2).
Most indoor and some outdoor plant species can be propagated in water. The rule is simple - trees, shrubs, and herbaceous plants that grow in humid areas or reproduce vegetatively (for example, Aroids) can be propagated in a humid environment, i.e., water. Such plants as succulents can be rooted in water too.
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.
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.
Cuttings need water for hydration, but also enough oxygen for roots to respire and grow. Using a substrate with adequate air porosity, and using the 1 to 5 moisture scale can help to prevent overwatering that leads to slow rooting and increased risk of disease.
If you root your cutting in water, it develops roots that are best adapted to get what they need from water rather than from soil, Clark pointed out. If you move the plant immediately from water to soil, the plant may be stressed. Instead, add a small amount of soil to the water that you're using to root your cutting.