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.
Most plants will not root well in full sun, so place the cuttings in a location where they will receive a 50/50 ratio of shade to dappled sunlight. For most plants, cuttings thrive on warmth and humidity, and the growing medium should be kept evenly moist but not drenched while roots develop.
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.
Roots grow in the dark soil to anchor the plant and to absorb mineral nutrients and water. It has been reported that light can penetrate less than several millimeters due to the rather high absorbance of soil (Woolley and Stoller, 1978).
Sprinkle rooting hormone powder on a saucer. Dip the cutting in the powder, which will encourage root growth once it's planted.
Clip off the leaves on the lower half of the shoot so you have a bare stem to insert into your potting mix. Then, if you want, dip the end of your stem in rooting hormone. This generally helps cuttings root more quickly.
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.
Full-spectrum light that mimics natural sunlight is the best for indoor growing. For controlling specific aspects of plant growth and flowering, combinations of higher intensity light in the red and blue wavelength ranges are useful.
Blue Light Spectrum (400–500 nm)
It's essential for seedlings and young plants during vegetative stages as they establish a healthy root and stem structure – and especially important when stem stretching must be reduced.
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.
You will also need a warm, light windowsill on which to put the cuttings, or a greenhouse – either way, they must be kept out of direct sunlight. Once the stem loses contact with the roots, it starts a rapid process of wilting, so cuttings should be taken in the morning or evening, but never in midday sun.
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.
Most crops benefit greatly from what Stuppy Greenhouse Regional Account Manager Armando Echavarria calls “warm feet and a cool head.” This means heating soil at the root zone, which promotes seed germination and accelerates rooting and growth in young plants.
Add fresh, tepid water when needed. 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. If the water is murky, we recommend replacing it for the health of the growing root system.
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.
Cover the Pot With Plastic
Place the container with the cutting into a plastic bag. The bag will keep the humidity high and hold in heat. Do not seal the bag completely because some airflow is necessary to prevent fungal rot.
Light Color
Red light stimulates vegetative growth and flowering (but if a plant gets too much, it will become tall and spindly). Blue light regulates plant growth, which makes it ideal for growing foliage plants and short, stocky seedlings (but too much will result in stunted plants).
Blue light helps plants produce chlorophyll, the pigment they need to grow. It also helps encourage germination and root development in young plants and seedlings. Red light regulates plant growth and helps plants produce flowers and fruit. Green light helps maximize photosynthesis.
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.
The problem is if the cutting is too long the plant is more likely to wilt and stress. If the cutting is wilting it's far more likely to fail and not generate roots. Smaller cuttings will lead to better success rates and overall better outcomes for you and your cuttings.
Phosphorus potassium &Nitrogen are the essential nutrients to support root growth for plants. They encourage plants to put down a dense collection of new roots and strengthen existing roots as they develop. Phosphorus helps establish healthy root systems at the beginning of growth.
Similarly, cinnamon also does not contain any rooting hormones. Cinnamon has some antimicrobial properties so it might help prevent bacterial growth that could harm your cutting. But it will not help your cuttings to create roots.
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.