Layer_(PSF)All plants propagate. Otherwise, they would go extinct. They all have the potential to propagate by seed or spores. However, some are more efficient at vegetative propagation from stems or roots. Of the later, a few propagate by seed so rarely that it is a wonder that they can evolve, since vegetatively propagated plants are clones, or genetically identical copies, of the original plants.

A single coastal redwood can live for thousands of years. Before such a tree dies, it clones itself by producing adventitious stems from its aging root system. These stems mature into new trees that can live for thousands of years more, only to repeat the process indefinitely. There is no opportunity to generate and share any slight genetic variations that are necessary to natural selection.

Well, this is probably more information than any of us need for our home gardens. It is only relevant to demonstrate than many plants are happy to propagate themselves vegetatively, or are at least conducive to simple vegetative propagation techniques. This is why most nursery plants are grown from cuttings, which are merely pieces of stem stuck into media and forced to grow roots.

For those of us who are not in the nursery industry, there is a more practical way to propagate a few copies of certain favorite plants. Sprawling groundcovers and vines like iceplant, knotweed, jasmine and ivy know all about it. So do many low growing succulents. Their lower stems develop roots where they lay on the ground, and grow into new plants. The process is known as ‘layering’.

Some low shrubby plants that might not layer naturally might be coerced to do so simply by getting a few of their lowest stems buried just below the surface of the soil, with a few inches of the tips sticking up. It helps to scratch off a patch of bark about a third of the way around the buried section of stem, and apply rooting hormone. Sturdy stems can be held down with rocks if necessary.

For most plants, layered stems can be buried about now, left through winter, and should be ready to be separated from the parent plants by next summer, just after any new growth matures. New plants will of course need to be watered generously until they develop enough roots to be self sufficient. Most plants with pliable stems that reach the soil can be layered. Junipers, euonymus, euryops, marguerites, boxwoods and carpet roses are some of the more popular candidates.

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12 thoughts on “Propagation Is No Big Mystery

  1. I would think that even with clonal propagation there will be some genetic changes due to accidental random mutations but these would be orders of magnitude slower than sexual reproduction. I have no idea if this is indeed true and would be interested to know if it is so.
    Thank you for the article. Informative and thought provoking as usual.

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    1. Mutation is very rare with cloning. It sometimes happens with genetically unstable plants that are prone to mutation anyway. For example, variegated andromeda reverts to plain green during propagation, but no more commonly than it does out in the nursery on in a landscape. Layering is a very reliable propagation technique, although it is not practical for producing large volumes of plants. Many plants are not true to type if grown from seed, and many of the most extensively bred plants do not make viable seed.

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  2. What a timely article! I was thinking of doing this very thing (layering?) with a flowering quince I have. In the past, I notice that my forsythia has done this naturally, via it’s low-growing branches. Can you suggest a brand of root hormone that you feel is most successful?

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    1. Flowering quince often does it without any help as well. It can form thickets of basal stems that can be divided almost like a tough perennial while dormant in winter. However, it seems that some of the contemporary cultivars do not develop such congested thickets. Anyway, I do not know if any of the rooting hormone products are any better than any other. I use the cheapest.

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    1. That is a good question. Both cherry and pineapple guava are very different. Both can be layered, and the new plants will fruit. However, the cherry is grafted. The layer (new plant) will not be grafted, so will lack whatever advantage that the understock provides. For example, if the understock is a dwarfing understock that keeps the original tree compact. The layer will might grow larger, with more open and awkward growth. (Winter pruning can help with open and awkward growth.) If the understock is more resistant to a particular soil-borne disease, the layer will lack that resistance to the same disease. It is all a matter of what the understock does for the parent tree. My peach is not grafted, and had done just fine on its own roots since 1985. (It is finally getting old now.) The pineapple guava is not grafted, so a layer would be genetically and physiologically identical to the parent tree. Because they are SO difficult to propagate by cuttings, and also because you probably do not need to propagate too many of them, I recommend layering. Just be aware that they are difficult to propagate by layering as well. They really do not want to form new roots. I would get an early start on layering, as soon as the rain starts (or even earlier if you do not mind watering it). Please do not be disappointed if it does not develop roots. They can be very stubborn. You will have serious bragging rights if it works.

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