Propagating plants

Easy ways to get more from your plants
Photo 1
The small tree, behind the yellow flowers, is a sucker of the large tree. The root from which it sprang has been cut and the little tree is growing on its own.

Don Parker
Photo 2
White-flowered sweet alyssum is growing in Tom Spear’s Hard Rock & Dynamite Railroad in Denver.

Don Parker
Photo 3
A small hosta is being divided using a sharp spade to cut out chunks of plants with some soil.

Joyce Parker
Photo 4
This small thyme (Thymus vulgaris ‘Silver Posie’, Zones 5-8) is a good candidate for making cuttings.

Don Parker
Photo 5
Sharp scissors are being sterilized in alcohol before cutting off the desired branch ends.

Don Parker
Photo 6
The cut end of the little branch has been coated with powdered rooting hormone and is being “stuck” into a hole made by a pencil in the cutting medium.

Don Parker
Photo 7
The pots containing the moist, soilless medium and cuttings have been placed under a plastic bag to maintain a humidity of 100%.
Don Parker
Photo 8
After two weeks, the cuttings have rooted and the bag has been removed.
Don Parker
Photo 9
Samples of moss and a cup of buttermilk are ready to be blended.

Don Parker
Photo 10
The buttermilk-moss mix is being poured onto three different kinds of rocks.
Don Parker
Photo 11
Fine moss growth has formed over most of the surface of the porous piece of brick on the left. Chunks of the moss have coalesced to form a colony on the right-hand rock. The smooth granite rock behind it failed to grow any moss.
Don Parker
Photo 12
Fine seeds can be more easily sown by placing them on a folded piece of paper.
Don Parker
There are ways to get more of the plants that you already have without buying them. Getting more for less is not only economical, but relatively easy. In this column I’ll describe how you can propagate plants by dividing, making cuttings, and saving seeds.

The easiest way to get more plants is to let the plants do their thing. For instance, groundcovers often spread by underground runners (rhizomes), flowering plants by seeds, some woody plants by layering (growing roots and a new plant where a branch touches the ground), and some by suckering (new plants growing from roots). An example of the latter is shown in photo 1, where a Washington hawthorn tree, grown in a pot to keep it small, produced a sucker from one of its escaped roots.

Sweet alyssum (Lobularia maritima) is a nice, flowering groundcover grown as an annual (photo 2). It often reappears the next year from seeds it drops, without any effort on our part. Seeds can be saved by collecting the older flower heads and planting the seeds elsewhere the next spring. The sweet alyssum Wonderland series is quite compact (3"-4" tall) and comes in a variety of colors.
When groundcover plants have spread further than you want, you can dig out chunks of soil containing the excess plants and move them to where you want to grow more. Other plants, hostas, for instance, can be divided by pushing a sharp spade into the clump and cutting out a small portion of the plant (photo 3). These divisions can be replanted in a new location where the soil has been prepared. The separated plants should be kept moist with wet paper towels or cloths, kept in the shade, and planted as promptly as possible.

Starting plants from cuttings
There are some important guidelines for making cuttings. First, cuttings should be taken from a healthy plant (photo 4). The plant should be watered well several hours before taking the cutting. Use a sharp blade that has been sterilized to reduce damage to the plant and to prevent infection (photo 5). Cuttings should be taken from the outer 4-5" of a branch that is actively growing; i.e., in the late spring or early summer. The branch tip should be supple (green bark), not a stiff, woody twig. Place the desired number of cut branch ends between damp paper towels.

Cuttings should be rooted in a soilless medium, which should be well draining and loose, to allow oxygen to penetrate to the newly forming roots. This medium can be perlite, vermiculite, sharp sand, or a combination of peat moss and any of the previous items. Place the medium in a small container deep enough to support the new root depth and water it well. Let it drain so that it is moist but not soggy wet.

Cuttings usually benefit by using a rooting hormone. Synthetic rooting hormone is most available in a powder form. There has been a concern that breathing the powder may have some health hazards, so using common sense and caution is wise. Although the powder form is easy to use and effective, there are also liquid synthetics and organic rooting substances. Honey and willow extract are two organic forms. Willow extract is available commercially, but may require some searching. Honey doesn’t give successful results as quickly as the synthetic stimulants and willow extract.

Put a small amount of the powdered rooting hormone on a piece of waxed paper and dip and roll the cut end in the powder. Make a hole in the soilless medium with a pencil and stick the treated cut end into the hole to a depth of about 1 to 1 1/2" (photo 6). Firm the mix around the cutting. Place a plastic bag over the container and put it in an indirectly lit area at room temperature (photo 7). Open the bag daily to allow some air circulation and make sure the medium stays moist with a mist of water. Check for root formation in two weeks by gently pulling on the cutting. If it resists movement, it is growing roots. Some plants will be ready in 10-14 days and other may take a month or more. Take off the plastic bag and continue growing the new plant in the rooting medium (photo 8). Repot the plant in potting soil when the root system is well established and there are signs of new leaves developing.

Propagating moss
You can get moss to grow on a rock in a shady, moist spot with a little encouragement. Here’s a tried-and-successful way to propagate moss. Collect moss from an area with plenty to spare. Place several chunks of it in a blender with a cup of buttermilk and blend well (photo 9). The buttermilk creates an acidic environment with enough nutrition to help the tiny fragments of moss take root and grow. Pour the buttermilk/moss mix over the desired rocks, place the rocks in a shady spot, and mist with an atomizer every few days, unless it rains (photo 10). In photo 11, the moss has colonized on the piece of brick and the rougher rock, but did not take on the smoother piece of granite. The photo was taken after the rocks had been outside all winter. Moss will colonize more quickly in warmer weather.

Seeds can be started indoors under grow-lights, or outdoors in their desired location. Plant seeds outdoors after the last average frost date and when the soil has warmed (night temperatures 50°F or higher). The soil should be soft and humusy or loose and well-draining, depending on what kind of plant you are growing. If the seeds are very fine, it is helpful to put them in a folded piece of paper to control the rate of dropping into the soil (photo 12). Keep the soil moist while the plants are germinating and during early growth. If the new plants are too crowded, you can transplant the extra ones to another site. Just make sure there are four true leaves already formed before attempting to move them.


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