Cuttings use energy to form new roots. If the cutting has leaves, most of the energy comes from photosynthesis. Expose these cuttings to bright light, but not direct sunlight, during the rooting period. If you use hardwood cuttings that have no leaves, the energy will come from reserves stored in the woody stem.
The cuttings require sunlight in order to root. Put them in a bright spot, but not in direct sunlight, or they will dry up and wilt. Various factors, including the plant species and soil temperature, will affect how long it takes for roots to form on the cuttings. The ideal temperature is 25 to 27°C.
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.
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.
In general, the rooting medium should be sterile, low in fertility, drain well enough to provide oxygen, and retain enough moisture to prevent water stress.
Auxin, a naturally occurring plant hormone, stimulates root formation. Several synthetic forms of auxin are sold as “rooting hormone.” Though some plants will root readily without treatment, application of rooting hormone to the base of the cutting will often improve your chance for success.
Warm growing medium temperatures accelerate cell division which leads to faster callusing, root initial development and subsequent root growth. It also speeds up the dry-down rate of the growing medium, which also helps encourage better rooting. The best way to warm the growing medium is through bottom heat.
We recommend a photoperiod of 12-13 hours for the propagation of most annuals, especially for long-day plants such as petunia. Light Intensity. Desirable levels of light vary, depending primarily on the stage of root development.
The best light cycle for rooting cuttings is generally 18 hours of light and 6 hours of darkness. Do not supply cuttings with 24 hours of light without any dark periods because this has shown to slow the rooting process down as plants root best with a sufficient dark period each day.
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.
Keep the container in a warm spot in the house, ideally in an area that has indirect bright light. Don't put the cutting in full sunlight until new leaves begin appearing along the stem.
Insert the cuttings into the compost to just below the lowest set of remaining leaves and cover with a clear plastic bag, so they stay moist. Keep the compost damp, but remove excess moisture, if necessary; too much, and you will get mould. You will know the plant is rooting well when you see new leaves appearing.
You can replace the water every few days, or simply top off the vessel with fresh water when it's looking low—as long as there is no murkiness or fungi growing.
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.
A common rooting temperature target is 73 to 77° F. To accomplish this, propagators who grow on the floor use in-floor heating, which is usually installed when the greenhouse is built. This is usually an energy-efficient method to increase the root-zone temperature and second- arily, the air temperature.
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.)
Roots themselves are also light-sensitive, so despite the fact that they will absolutely grow in a clear container in sunlight, you will find more success and faster propagation as well as avoiding algae growth in a dark glass or opaque container.
Providing too much moisture during propagation can result in rot and cutting loss. A practice often observed during propagation of unrooted cuttings is frequent, heavy misting, which provides too much moisture and should be avoided.
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. You can watch the roots develop if you have chosen a clear vessel for your cutting.
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.
Auxins stimulate root formation on the stem cuttings, e.g., IBA, IBA-alanine, NAA. NAA is synthetic auxin while IBA is considered as both natural and synthetic.
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.
Roots are dynamic and their growth is strongly affected by the environmental conditions found in the root zone. To survive and grow, they need Air (gas exchange), Water, Non-limiting Temperature, Carbohydrates, Minerals, Space, Low Soil Density, Microbial Associations and Non-toxic soil chemistry.