Detailed Explanation of Flower Layering Propagation Techniques, Easily Master the Operation Methods

1. Definition Layering propagation is the practice of wounding a section of a branch still growing on the mother plant, burying it in soil, and after it roots, cutting it away from the mother plant to make it an independent new plant. This method is mostly used for flowering shrubs whose stem nodes and internodes root easily naturally, or for woody flowers that are difficult to root by cuttings or grafting.

Advantages: Easy to succeed, simple method; branches that fail to root can be layered again the following year, so propagation material is not wasted.

Disadvantages: The plant's organism cannot be completely renewed, growth is not vigorous, and the number of plants produced is the smallest, so it is not suitable when producing large quantities of plants.

2. Methods (1) Simple layering method This method is divided into single-branch layering, continuous layering, and serpentine layering, etc.

① Single-branch layering: This method is mostly used for tree-type flowers, such as peach, cherry blossom, plum blossom, crabapple, magnolia, redbud, and hall crabapple. When propagating a small number, vigorous water sprouts on the main trunk can be used for single-branch layering (water sprouts are very long and relatively soft, so they are easy to bend down to the ground).

When layering, bend downward a one- or two-year-old branch or water sprout of the mother plant that is close to the ground, then wound or girdle the bent-down part; if conditions permit, apply 2000x10-6 NAA, then bury it in soil (about 15 cm deep), and use hooks to secure the part buried in the soil. At the same time, leave the tip portion of the layered branch exposed above the ground and tie and secure it with a bamboo pole so that it grows upright. After the wounded part has rooted, it can be cut away from the mother plant and planted separately.

② Continuous layering: This method is mostly used for vine-type flowers such as honeysuckle, crape myrtle, Boston ivy, banksia rose, Chinese trumpet creeper, and grape. These flowers and trees have very strong rooting ability; when they encounter moist soil, they root naturally, and the axillary buds at the nodes can also sprout at the same time and send up new shoots.   

When layering, first gently wound the node portions of branches of the mother plant that are close to the ground, then shallowly bury the wounded parts in a previously dug trench, with a depth not exceeding 3 cm, so that the branch tips are exposed above the ground. After a period of time, the node portions buried in the soil can sprout new roots, and soon the axillary buds on the nodes will also sprout and emerge through the soil surface. After the young plants are mature, use a sharp knife to reach deep into the soil layer and cut apart the internodes of each section. After more than about half a year of cultivation, they can be transplanted.

③ Serpentine layering: This method is mostly used for flowering shrubs such as rose, winter jasmine, and forsythia. Their axillary buds cannot tolerate waterlogging, so continuous layering cannot be used to bury the entire branch in soil, otherwise the axillary buds often rot and cannot send out new branches.

The correct method is to bury the branch in a wavy manner node by node in the soil, with one node buried in the soil and one node exposed above the soil surface. At the same time, secure the portions buried in the soil with wire or similar materials to prevent them from springing back. Generally no wounding is needed. After 20 to 30 days, roots can develop, and at this time cut apart the exposed internode portions section by section.

(2) Mound layering method This is mostly used for flowers and trees whose branches are difficult to bend, that are strongly clump-forming, and that produce many root suckers, such as elm-leaved spirea, pearl bush, spectabilis, and Amur honeysuckle. Because these flowers and trees have weak branching ability, no obvious nodes on the branches, inconspicuous axillary buds, and relatively thick and sturdy branches, it is quite difficult to bend them down. However, after hilling up soil, the branches can be softened and induced to root, and a large number of plants can be obtained at one time. This method is best carried out during the peak growing season.

Select perennial clumping old plants as mother stock. First carry out girdling on the lower part of the branches at 20 to 30 cm above the ground, then mound soil to bury the lower half of the entire clump. After burying, keep the mound moist regularly. After a period of time, new roots grow from the latent buds at the girdling wound. Wait until before sprouting in early spring of the following year, dig open the mound, cut off each one below the new roots, and then transplant.

(3) Air layering method This method is used for evergreen flowers and trees whose branches are difficult to root and are also not easy to bend, such as white orchid, Aglaia odorata, Michelia figo, croton, bougainvillea, camellia, rhododendron, and kumquat. It is generally carried out during the peak growing season.

This method does not bend the branch down onto the ground. Instead, select a well-developed two-year-old branch in the canopy. First make a deep wound below a node in the middle of the branch, preferably peeling off a ring of bark 0.3 cm wide. Then use a plastic bag (or bamboo tube) filled with peat soil, mountain soil, moss, etc. to wrap around the branch, water thoroughly, tie and secure the bag opening (or bamboo tube), and supply water promptly afterward to keep the growing medium moist regularly. After rooting, cut it away from the mother plant below the bag (or tube), remove the wrapping material, plant it with the soil into a pot, and place it under light shade for care. After a large number of new shoots sprout, expose it to full light.