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By Michael O’Brien, Advanced Extension Master Gardener
A plant runner is usually a horizontal long thin stem that grows outward from the mother plant. The long stem creates widely spaced new shoots, which can then become new plants. If the runner grows underground it is called a rhizome. Although it is underground, like most plant roots, a rhizome is not a type of root, as roots do not grow shoots. Many different types of grasses grow rhizomes. If the runner grows leaves and has photosynthesizing abilities it is called a stolon. If the runner is not a stolon it must remain attached to the mother plant. The runners develop roots to become a new daughter plant and, when it is old enough, it will develop runners of its own. A plant that creates runners can quickly spread over a wide area and can choke out other plants.
So, what’s are the benefit to a plant that develops runners? These plants don’t have to create large amounts of energy to develop seeds, though it doesn’t mean they won’t create seeds too. A well-known example of a plant that develops runners is a strawberry plant, Fragaria × ananassa. A mother plant will develop runners and those runners will continue to grow. As that runner is growing, new daughter plants are developing. The daughter plants will be an exact replica of the mother plant. The mother plant will also produce fruit and the seeds will then grow on the fruit. Another example is the Spider plant, Chlorophytum comosum. The Spider plant creates daughter plants and flowers. These flowers, when pollinated, will develop a seed pod though no edible fruit.
A good example of a plant that grows stolons is the Boston fern, Nephrolepis exaltata. The Boston fern will develop a stolon and several new daughter plants. Again the daughter plants are identical to the mother plant. However, if the stolon breaks off the mother plant the stolon can continue to grow which will continue to produce more daughter plants. Ferns, in general, grow stolons.
If the rhizome is broken from the mother plant, it can continue to grow. This type of plant can become a real problem when tending a garden. Each broken piece of the rhizome can continue to grow until the garden is filled with this plant, can be referred to as a weed.
This picture shows a Longhorn Sumac, Rhus typhina, growing many daughter plants. It’s easy to see how this can quickly become a problem in a garden.
Michael O’Brien, Advanced Extension Master Gardener
In the previous article about runners, stolons and rhizomes, if these plant parts are left to their own they will quickly take over a large area. In the same respect these three characteristics create an opportunity to make new plants that can grow in places where they are desirable.
With runners, a few daughter plants are growing on a long stem of the mother plant. As these daughter plants are starting out, their roots are not developed enough to grow independently of the mother. If runners are in the garden, place soil on the runners and around any daughter plants and lightly water regularly to encourage growth. When the daughter plant begins to grow vigorously, it will develop an independent root system from the mother plant. When the daughter plant grows a strong, healthy root system, the runner will die. At this time the daughter plant can be gently dug up and replanted in a desirable spot in the garden.
Otherwise, take a small planter and fill it with potting soil. Dig a hole in the ground near the daughter plant. Insert the planter in the newly dug hole and lay the daughter plant on top of the potting soil in the planter. Place soil on the runner and around the daughter plant to anchor it in place. Water gently and frequently. When the runner dies off, the planter can be dug up with the daughter plant. It is now growing independently of the mother plant and is well established.
Also in the previous article, I talked about the Spider plant, Chlorophytum comosum. The Spider plant is a fun plant to experiment with different types of rooting techniques. When selecting a daughter plant, choose one that has some root nubs on the bottom of the plant. Cut the daughter with a section of the runner. The remaining nutrients in the runner will help to feed the daughter plant while it’s alive so make the cutting long enough to help the new plant. Using a small planter filled with potting soil, place the daughter plant on top soil and lightly push it into the dry soft soil. Make sure the root nubs make good contact with the soil. Lightly water the soil: never drench the soil with water. Keep in lightly lit area.
There is another technique that can be used with water. Select the daughter plant with root nubs. This time the runner is cut as close to the daughter plant as possible without hurting the plant. Using a small cup fill about 1/3 of the cup with water. Place the daughter plant in the cup, the water should be just touching the root nubs. Check daily because the water will evaporate quickly, especially when the roots begin to develop. Using a nutrient solution instead of water can quicken root development. The nutrient being mixed with water should have a ratio of 10-0-0. That is the N,P,K ratio that shows on the nutrient label. An educational experiment for kids to see root development. A cotton ball can also be put in the bottom of the cup with the daughter plant sitting on top of it. The cotton ball wicks the water right to the root zone while creating enough air too.
Stolons are a little different in regards to creating new plants. Stolons can break off the mother plant and remain alive. Usually daughter plants have no roots but stolons do. As mentioned previously with runners, stolons can be buried with soil surrounding the daughter plant. Water gently and frequently. When the daughter plant is growing vigorously it is now safe to transplant. Keep in mind the stolon is still alive. It is important to cut the daughter plant off the stolon before moving this plant.
The Boston fern, Nephrolepis exaltata, was also mentioned in the previous article. The Boston fern has long stolons hanging down the plant. The daughter plant doesn’t have any roots at this time. Gently cut a piece of the stolon along with a daughter plant. Lay the bottom of the daughter plant on top of some lightly moistened, never wet, potting soil. Moistened soil has a nice balance of water and air which entices the plant to grow roots. Place some moss, it can be sphagnum moss, around the plant to hold it in place. Give the new plant a very small amounts of water weekly and keep it in cool lightly lit area. When the new plant begins growing new shoots, roots will be growing too. In roughly a month’s time this plant can be transplanted to its new location.
Working with rhizomes is a little bit different. While looking at the garden it is easy to see a string of young daughters growing out of the ground. Using the picture from the previous article, the plant growing in the picture is a Longhorn Sumac, Rhus typhina with daughter plants. Begin by gentle loosening the soil to avoid damaging too many roots. Once the rhizome is exposed and loosened from the soil, cut the rhizome before and after the daughter plant. Make sure the daughter plant has roots. Replant the daughter plant in its new location in the garden or in a planter with potting soil. If the daughter plant is put in a planter, be sure to water it well enough to get the air out of the soil. If there is too much air in the soil the roots will dry out and the plant will die. The planter should have drain holes to allow excess water to drain out. If the daughter plant is planted in the garden, then water well after it has been planted. The new plant should be lightly shaded to avoid stress.