Making Plant Babies: Propagation Tips
By Lois Hoffman
Ron has a viburnum bush in his backyard. Each spring it has the most beautiful and fragrant snowball-like blooms that have such heavenly scents. I want a start of one from his bush. Here lies the problem.
Unlike lilac bushes that throw up new shoots each year where you can merely dig one up and replant it wherever you would like, the viburnum doesn’t produce shoots. So, before delving into this process of propagating plants, I was all set to graft a new one. However, there are distinct differences between grafting and taking a cutting. Each process works better for different varieties.
Taking a cutting requires no time or money but a lot of patience to root a branch to grow a new tree. It is the simplest method of propagation and can be used for both deciduous and evergreens. Branch cuttings become a complete, new plant that is identical to the parent plant. Branches less than one year old work best and cuttings usually grow better than trying to start the tree or bush from seed. They also mature faster than from seed, developing roots within a few months.
The first step is to prepare the planter. Multiple cuttings can be grown in one planter, just make sure that you select a space that is large enough. Fill the planter with sterile, soil-less potting medium and then water it until it feels moist all the way through and settles. Then make one-inch diameter holes for each of the cuttings. Taking multiple cuttings ensures a greater rate of success.
When selecting a branch, choose a healthy one about 10 inches long that includes leaves. Cut it from the tree or shrub on a 45-degree angle using clean pruning shears. The rule of thumb is to take softwood cuttings in spring from new stems; cut semi-hardwood in summer or fall from current-season stems; and hardwood cuttings are taken from the previous season’s growth in winter.
To prepare the cutting, remove leaves and needles from the bottom two thirds of the stem and then wound the bottom couple of inches of it by making vertical cuts on each side with a sharp knife, taking care to stay in the surface wood. This allows more rooting hormone and water to be absorbed while increasing cell division.
Pour one teaspoon of rooting hormone into a clean saucer. Dip the wounded end of the cutting into the hormone, rolling the bottom wounded part of the stem in it until it is coated. Shake off the excess and place the hormone-covered part into one of the holes in the potting medium. Build the mix around the cutting to hold it into place and mist the soil and leaves.
Place a few sticks into the planter around the potting mix and cover with plastic film or lightweight greenhouse plastic to trap humidity. Set in indirect light and keep the temperature around 65 degrees.
Keep the soil moist all the way through and mist the leaves daily. Check the cutting daily for root development by gently tugging on a branch to see if roots have started. When roots have formed, plant the new plant in a 4-inch planter filled with sterile potting soil. Place it in indirect sunlight and keep the soil moist. Slowly harden it off to outdoor conditions after one year of growth before directly planting it in the ground.
Although taking a cutting is a pretty simple process, there are a few tips that will help to ensure success. Water the tree deeply the day before the cutting. This will make sure there is plenty of water in the branches. Process the cutting right after taking it to prevent it from drying out. Dip pruning shears in a solution of 10% bleach and 90% water to prevent the spread of disease. Be patient, sometimes it takes up to three months for roots to develop.
Grafting is one of the most difficult types of propagation. Essentially, it is joining parts from two or more plants so they appear to grow as one plant. The offspring are genetically identical to the parent plant. The nitty gritty is that a piece of a mature tree, called a scion, is joined to a seedling, which is the rootstock. The scion will become the new trunk and branches while the rootstock will become the new root system. There are two distinct types of grafting, veneer and cleft.
In veneer grafting, bark is removed from one side of the scion and then bark that is roughly the same size is removed from the rootstock. The flap of bark should be left on the bottom of the rootstock to hold the scion in place. Both of these cuts should be made at a 45-degree angle so they will fit together nicely. The exposed cambium, the active layer of cells located between the bark and woody portion of the stem or branch, of the scion and rootstock should be placed together and held in place with grafting tape.
It is critical that the cuts be smooth and flat so they can become a good fit together. Using a grafting knife, which is beveled only on one side, is best for this process.
Cleft grafting is basically the same process, but a different type of cut is made. The top of the rootstock is cut and then a cut approximately a half inch deep is made down the middle of the rootstock. The scion is prepared by cutting a thin wedge at its base which fits into the cut in the rootstock. Again, grafting tape holds the two parts securely in place.
Both types of grafting should be complete within four to seven weeks. When the graft is successful, the new plant will begin to grow leaves.
Both processes, taking cuttings and grafting, are done to grow new plants. Much of the time in grafting, the purpose is to take the best properties of two or more plants and combine them into a new plant, hopefully one that is superior to the single plants. This is big business in the fruit industry.
Either way, it is fun to try this on your own. Animal breeders do it all the time, to make a breed stronger, bigger, better. It is the same with plants. As for the viburnum bush, it is next on my bucket list…to see if I can make a new plant baby!
Images courtesy of Getty Images
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