The cost of purchasing a plant reflects the time and effort it has taken to start the plant and grow it to a salable size.
Annuals are inexpensive as they propagate easily by seed or cuttings. In some cases, the seeds are light sensitive, which means that the seeds either need to be exposed to the light or kept in the dark for germination to occur. But for the most part, they germinate within a week or two in greenhouse conditions.
Greenhouses have been starting more annuals from cuttings as plants from cuttings tend to mature faster than seeded plants. In the competitive plant market, a few extra weeks of heating a greenhouse during the winter can make a huge difference to the bottom line.
There are perennials that start easily from seed. Greenhouses that sell a small variety of perennials have started them from seed.
Trees and shrubs can be started by seed, sexual reproduction or cuttings, asexual reproduction.
When seed is used, the DNA within the plant varies, producing slightly different plants. Characteristics such as shape, colour and rate of growth will be noticeably different. Other characteristics, such as disease resistance, will only come into play when the plants are subjected to a disease.
Plants from cuttings are all exactly the same. Any difference in size, shape and rate of growth comes from differences in the environment. They will either all be resistant to a disease or not.
Nature protects seeds by keeping them dormant until perfect conditions are achieved for them to germinate. In the case of trees, shrubs and many perennials, it often involves periods of wet, cold stratification, followed by warm conditions. This can be achieved by placing seeds in a moist, sterilized soil mixture and putting it in the fridge for up to three months, then transferring it to a growing media. As each variety of plant is different, it is best to research the variety before attempting to germinate the plant from seed.
In the spring just before the leaves appear, willows and dogwood plants are easy to start from cuttings. Select a healthy plant and take cuttings from last year’s growth that is thin and flexible, without any side branches. The cutting should have five to seven nodes. Place the cut ends into soil in a container or section of garden that has loose, moist soil. Press the soil down around the cuttings, removing large air pockets. Water well and keep the soil moist but not wet throughout the summer. The cuttings will callus over, put out roots and then leaves. By fall, the new plants will be ready to transplant.
Young tree and shrub branches that lean down and touch a moist ground can develop roots and become a viable plant. This process is called layering and often happens in nature and is easy to duplicate.
Start by choosing a young, flexible branch with few if any lateral branches that easily reaches the ground. Take a knife and cut away the bark on the bottom of the branch under the node. Dig a hole approximately six inches (15 cm) deep that aligns with the area on the branch where the bark was removed.
Set the cut area of the branch in the hole and backfill with soil that contains organic matter. Anchor the branch in place using a U-shaped pin. Keep the soil moist throughout the season. Do not check to see if roots have formed until the next spring. It can take two growing seasons for a sufficient amount of roots to develop to support the new plant.
Once roots have formed, cut the branch back to another branch or node and dig the new plant.
Trees and shrubs can be propagated at home but patience is needed as the plants will take two to five years to reach the size of what is sold in stores.
Linda Tomlinson is a horticulturalist who lives near Rocky Mountain House. She can be reached at email@example.com.