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Proper Plant Propagation – Part II

In this installment we will discuss the various types of layering, division, separation, grafting, and budding.

Layering

Plant stems, still attached to the parent, may form roots where they touch rooting medium. When severed from parent plant, the rooted stem becomes a new plant. This method is highly successful as it prevents the water stress and carbohydrate shortage that plague the various cutting methods. The rooting medium should provide aeration and a constant supply of moisture.

Division

Division may be thought of as a modification of layering, because the new plants are formed before they are detached from their parent plants.

Separation

Separation is a term applied to the propagation of plants that produce bulbs or corms that multiply.

Grafting and Budding

Both grafting and budding are methods of propagation that join parts of two different plants so that they will grow as one. They are used for propagating cultivars that don’t root well as cuttings or whose original root system is inadequate. You can add one or more new cultivars to existing fruit and nut trees using these methods. The portion to be propagated is called the scion, consisting of a piece of shoot with dormant buds that will produce a stem and branches. The rootstock will provide the new plants root system and sometimes the lower portion of the stem.

When the scion is grafted onto the rootstock the cambium (a layer of cells located between the stem’s xylem and phloem) of the two must touch. New xylem and phloem cells will originate from the cambial tissues. Four conditions must also be met for successful grafting:

  1. Rootstock and scion must be compatible
  2. Each plant must be at the proper developmental stage
  3. The cambial layers of rootstock and scion must meet
  4. Graft union must be kept moist until the wound heals

Cleft Grafting – is most often used to change the cultivar or top growth of a shoot or young tree, usually a seedling. It can be especially successful done in early spring. Collect scion wood that is 3/8 to 5/8 inch in diameter. Cut a limb or small trunk of the tree for the rootstock perpendicular to its length. Make a two-inch vertical cut through the center of the first cut, being careful not to tear the tender bark. Use a small wedge to keep this cut open.

Prepare two scion pieces three to four inches long. Cut lower end of each scion piece into a wedge; insert the scions at the outer edges of the cut in the stock. Tilt the scions’ tops slightly outward to ensure cambial layers of the scions and rootstock touch. Remove the wedge that is keeping the slit open and cover all cut surfaces with grafting wax.  When grafting, cut back all of the limbs of rootstock. Also, as the new cultivar increases in leafing out, gradually reduce the leafage of old cultivar. Over the next two years, the new one should completely take over. Removing the foliage from old cultivar all at once will greatly increase the chances of shock for your grafting and causes excessive suckering.  The scions may also grow too fast, causing them to be susceptible to wind damage, so go slow.

Bark Grafting – this can be preformed on large limbs, unlike most grafting methods. Collect scion wood that is 3/8 to 1/2-inch in diameter when the plant is dormant; wrap wood in moist paper toweling and place inside a plastic bag in your refrigerator. Saw off a limb or the trunk of the rootstock at right angle to itself. In spring, when it is easiest to separate the bark from the wood, make a ½-inch diagonal cut on one side of scion and 1- to 1½-inch cut on the other side. Leave two buds above the longer cut. Cut through bark of rootstock a little wider than the scion. Remove the top third of the bark from this cut area and insert the scion with longer cut against the wood. Nail graft in place with flat-headed, wire nails and cover all wounds with grafting wax. Cut back selected limbs of old cultivar as described under cleft grafting.

Whip or Tongue Grafting – often used for material that is ¼ to ½ inch in diameter. The rootstock and scion are usually the same diameter; however, the scion may be narrower. This is a strong graft type, as it heals quickly and provides excellent cambial coverage. Make one diagonal cut, 2½ inches long, at the top of the rootstock and a matching cut on the bottom of the scion. On the cut surface, make a slice downward into the rootstock and a matching one up into the scion so that pieces will interlock. Fit pieces together, tie the splice, and cover the union with grafting wax.

Care of Grafts

Two to three weeks after preparing grafts, inspect wax for cracking and rewax if cracks are present. After this, the graft should be strong enough that no further waxing should be needed. If using strong cord or grafting tape, cut it shortly after new growth appears to prevent girdling and possible death to new cultivar. Rubber budding strips have small advantage over other materials, as they expand with growth. They do not need to be cut because they will deteriorate and break with time.

Budding

Budding is the union of a rootstock with a scion containing a small piece of bark and one bud. It is useful when scion material is limited. It forms a stronger union and heals faster than grafts. It is common in the propagation of roses.

Care of Buds

Make bud grafts in August. Next spring, force buds to develop by removing the stock three to four inches above union; tie the new shoot to the stub to prevent wind damage. When the union is proven strong, cut the stub off close to the budded area.

For more information, including which plants respond best to each type of propagation, visit the links below:

https://plantpropagation.com/

https://www.mastergardenproducts.com/gardenerscorner/new_page_4.htm

https://www.uaf.edu/ces/districts/tanana/mg/manual/chapters/4-Plant-Propagation.pdf

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