Old egg cartons with the tops cut off make great planters! People have long used them to start seedlings, but they also make awesome containers for propagating cuttings. They are perfectly separated so that you can transplant them in to bigger planters once they develop sufficient root systems.
Clean, coarse construction-grade sand may be used for rooting cuttings. Avoid very fine sand because it has poor aeration, which hampers root formation. A mixture of half sand and half peat moss is a better rooting medium. Vermiculite, a lightweight expanded mica product, is suitable for rooting cuttings.
A long time ago, I wrote about my plastic clamshell salad container propagation box. You know, the ones that the mixed greens come in? I usually didn't keep the lid on it, but I kept it in Ramona's bathroom window. It still did an amazing job of helping plants root.
Quick tip: While you can theoretically use almost any small container to water propagate, clear glass is preferable because it allows you to easily monitor the root growth and water level/quality. Plus, it's fun to easily see those roots developing!
Clear glass vessels are actually better for supporting root growth—and they look pretty, too. However, you can propagate vigorous new plants from cuttings with an opaque container like a ceramic vase or even a coffee can.
Six-inch pots work well as a container. They can hold several cuttings and are a good size that will fit on a windowsill or under a grow light. You can also use cell packs, flats or even egg cartons.
Mason jars are another great option for smaller cuttings. Once you can see a few inches of roots, it's time to plant in soil. Clear containers are always best for this type of process so you can see what's going on. As mentioned above, any plant you can locate a node, will be great for this.
We recommend using clear glass for these plant propagation techniques because it will allow you to track root growth more easily, but any tall, skinny, watertight container will work in a pinch.
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.
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.
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.
Plant pots (PP, LDPE, HDPE) are lightweight and cheap, but difficult to recycle once broken. Alternatives include terracotta, coir, fibre, Vipots, bamboo and waste cardboard. Single-use biodegradable containers are widely available.
Allowing plants to dehydrate
Another way to reduce water loss is to keep the cuttings in a humid atmosphere – place a clear plastic bag over individual pots or use a propagator with a lid.
Don't underestimate temperature either, most cuttings root dramatically faster if you keep them around 24°C to 26°C. Keep the container small. The plant naturally creates its own hormones to stimulate the growth of roots.
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.
Cuttings planted in soil will grow roots more slowly. Make sure to keep soil / moss moist. This is easiest if you tent with a plastic bag or use a covered container such as a clean, lidded take-out food container. Check the plants weekly for moisture and growth.
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.
Most softwood cuttings are taken in spring and early summer, from the tender new growth of the season. If potted by mid-summer they will develop sufficient roots to survive the winter, otherwise pot up in the following spring.
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.)
In nature roots grow in the dark and away from light (negative phototropism). However, most current research in root biology has been carried out with the root system grown in the presence of light.
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.
You can place multiple cuttings from different plants in the same container as long as the root nodes of each are fully submerged in the water while any remaining leaves are free above the water. You could also place some rocks or pebbles in the container if the cuttings need to be secured in place.
Put your cuttings in a jar of tepid water and put the jar somewhere that receives bright, indirect light. Within a few days, you should see tiny roots sprouting. Replace the water once a week or so, when it looks like it's getting grimy, and top it off when the water level gets lower.
You can leave the container uncovered or cover it with glass or plastic. If covered the container will create a micro-climate so that the plants will not require watering unless the container is in a sunny spot. If the glass clouds over remove the cover and leave it off until the condensation disappears.