COMPETENCIES TO DEVELOP

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102

C O M P E T E N C I E S T O D E V E L O P

After studying this unit, you should be able to: list five plants commonly propagated by hardwood cuttings. select, collect, and label mature cutting wood from one of the five identified parent plants. make and store 10 hardwood cuttings. line out cuttings in the field or greenhouse at the proper planting time. keep accurate records of the percentage of cuttings that root.

M A T E R I A L S

■ cutting wood ■ string to tie bundles ■ storage area ■ propagating knife ■ labels and waterproof pen or pencil to mark labels

O B J E C T I V E

To perform the six steps in taking hardwood cuttings so that success in rooting 60 to 80 percent of the cut-tings is achieved.

K E Y T E R M S

bare root callus deciduous dormant hardwood cutting lining out

C O M P E T E N C I E S T O D E V E L O

J E C T I V E

Hardwood Cuttings

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PROPAGATION by hardwood cuttings is one of the easiest and least expensive methods of vegetative or asexual propagation. Cuttings are prepared in the dormant winter season when time usually is more available to the propagator. Hardwood cuttings may be shipped long distances or stored for long periods of time. Expensive misting equipment or rooting benches are not needed, and the necessary cold storage may be done outdoors in low-cost facilities if temperatures are 50°F (10°C) or lower. Many decidu-ous woody plants are easily propagated by hardwood cuttings. Figure 8–1 lists deciduous and narrowleaf evergreens propagated by hardwood cuttings.

Propagation by hardwood cuttings differs from softwood and semihardwood cuttings in several ways:

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the time of year in which the cuttings are taken,

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the hardness, or maturity, of wood used for the cuttings,

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the usual absence of leaves on the cut-tings, and

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the storage of cuttings instead of immedi-ate planting.

Selecting the Cutting Wood

Wood for hardwood cuttings is generally taken from current season’s growth, as is done with softwood cuttings. The wood is cut from the ends of branches or from long shoots that grow from the base of the plant (Figure 8–2). This material may be gathered soon after the plants become dormant. Plants that are dormant have lost their leaves and are preparing for the win-ter rest cycle. Cuttings may be taken throughout the winter months. The wood taken is current year’s growth, but it is now mature or hardwood. Plants that are healthy, vigorous, and grown in full sunlight yield cutting wood with more stored carbohydrates and more vigor in rooting.

FIGURE 8–1 Deciduous and narrowleaf evergreens propagated by hardwood cuttings.

SOME DECIDUOUS PLANTS GENERALLY PROPAGATED BY HARDWOOD CUTTINGS

blueberry mock orange

currant (ribes) mulberry

deutzia Persian lilac

dogwood plum

euonymous pomegranate fig privet

forsythia rosa multiflora gooseberry spirea

grape weigela honeysuckle wisteria kerria

SOME NARROWLEAF EVERGREENS PROPAGATED BY HARDWOOD CUTTINGS chamaecyparis spruce hemlock thuja juniper yew pine

P r o c e d u r e

Six Steps in Taking Hardwood Cuttings

1. Identify the plant to be propagated and select proper cutting wood.

2. Collect wood for cuttings. 3. Make the cuttings.

4. Store the cuttings.

5. Line out or plant the cuttings.

6. Determine rooting percentage of the cuttings.

G R E E N T I P

Using a natural hardwood cutting program for your plantings is not only economical, but the program provides greater control of the plants overall health, thus, reducing the need for chemical spraying. You will have higher producing plants, and you will protect the health of the surrounding plants.

Collecting the Cutting Wood

Using a sharp knife or hand pruner, cut the selected wood from the parent plants. Because the wood has no leaves, drying out is not as

Delmar/Cengage Learning

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Taking Cuttings

Cuttings, usually 6 to 8 inches long, are made with a sharp knife or pruning shears. The bot-tom cut is made just below a node and the top cut about 1 inch above a node or bud (B of Figure 8–3). Make the bottom cut (end toward the base of the plant) at a 45-degree angle and the top cut at a 90-degree angle so that cuttings can be planted bottom down. The diameter of cutting wood is not extremely important. Medi-um-sized wood, however, tends to survive stor-age and root better than wood that is very thin.

Cuttings should be made early enough so that they may be stored 6 to 8 weeks prior to planting.

Storage of Cuttings

The cuttings are treated with a rooting hor-mone for better growth. The finished cuttings are then tied in bundles for storage. They should be placed so that all the tops are on the same end of the bundle and buried in moist sawdust or similar material. The bundles should not be tightly sealed; the cuttings are alive and need oxygen to remain healthy. A tight seal could also cause excess moisture to collect, resulting in rotting.

The storage period allows the cut ends of the cuttings to callus and the rooting process to begin. Callus formation, which occurs dur-ing storage, is an advantage when cuttdur-ings are placed outdoors for rooting under drying con-ditions because callused cuttings root more quickly. New roots begin to grow during storage and may be visible at this point.

The cuttings may be buried outside in sand-filled containers in a well-drained area. Outside temperatures must be cold enough to prevent growth beginning at the tops of the cuttings during the storage period. During the first 4 weeks of storage, the temperature should be 50 to 55°F (10 to 13°C). This relatively high temperature is favorable for callus formation. After callus has formed, the temperature may be lowered to below 40°F (4°C) but never below 32°F (0°C). This lower temperature prevents growth on the tops before the cuttings are lined out (planted).

much of a problem as it is with softwood cut-tings. Label the cuttings according to variety name and date collected. The wood may be made into 6- to 8-inch cuttings for immediate use or stored in a cool moist place (below 50°F [10°C]) for later use (Figure 8–3). If stored, the branches should never be allowed to dry out or become too wet. A covering of moist (but not wet) sawdust, sand, or peat moss works well to maintain moisture. There should be little variation in temperature during stor-age because temperature variation tends to hasten drying.

FIGURE 8–3 (A) illustrates grape hardwood cutting wood as collected from the plant. (Stems are longer than shown in the photograph.) (B) shows hardwood cuttings cut to the proper length and ready to be tied in bundles and stored.

FIGURE 8–2 Strong, reddish-brown young shoots growing from the base of a blueberry plant. These shoots (located to the left of the parent plant) make excellent hardwood cuttings. Notice that the leaves have all dropped off the plant; this is because the plant is dormant.

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Lining Out Cuttings

As soon as the soil is ready in the spring, the cut-tings are planted outside. This process is known to nursery workers as lining out. Before lining out the cuttings, the soil must be prepared. A well-drained, sunny site with some wind protec-tion is best.

Rows are dug deeply enough so that the cut-ting can be covered with soil with only the top bud remaining above the soil level (Figure 8–4). If they are to be left for only 1 year, the cuttings are placed 6 inches apart in rows 1 foot apart. When the cuttings are to be left for more than 1 year or when especially fast growing plants are involved, the cuttings are spaced 9 to 10 inches apart and in rows 2 to 3 feet apart.

A small shovel or other tool is used to break the soil. The cuttings are placed in the soil at the depth described above. The cutting should not be pushed into the soil under pressure; this could damage the tissue or break the cutting. After the cutting is placed in the row, the soil is pressed firmly around the cutting. The soil sur-face may then be mulched to help hold moisture and control weeds or cultivated for weed con-trol. The soil should never be allowed to dry out around the cuttings. Provision should be made for watering as needed.

The number of plants that will eventually root depends upon the variety of the plant. How-ever, between 60 percent and 80 percent of the cuttings can be expected to root and grow.

As the weather becomes warm, the cuttings develop leaves and shoots although they may not yet be rooted. However, if growth continues into the summer months, it is almost certain

that the cuttings have rooted. The care required beyond this stage varies with the plant being propagated.

Narrowleaf evergreens propagated by hard-wood cuttings are often very difficult and slow to root. In general, the slow-growing Juniperus species root easily, the yews fairly easily, and the upright junipers, spruces, and hemlocks with diffi-culty. Pines are extremely difficult to root. Rooting hormones with high concentrations of indole-butyric acid (0.8 percent to 1.0 percent actual chemical solution or powder) are usually benefi-cial. These cuttings are taken from late fall to late winter and are best rooted in a greenhouse under high light intensity and in high humidity. This is achieved by placing the cuttings under plastic or using a misting system as specified for softwood and semihardwood cuttings. Cuttings should also be dipped in a fungicide such as captan to prevent rotting. Rooting media and other environmental conditions are essentially the same as those for softwood and semihardwood cuttings.

Hardwood cuttings of deciduous plants do not require the extensive care given to soft-wood and semihardsoft-wood cuttings. Because no leaves are present in the initial rooting stages, the demand for moisture is not high, and these cuttings need not be placed under plastic or in a mist system. The evergreen hardwood cutting, which does have needles at the time of rooting, must be handled as softwood cuttings are.

Rooted cuttings of deciduous plants are usu-ally dug for transplanting when they are dormant and without leaves. They may be dug bare root. Evergreens, however, that have needles should be dug with a ball of soil attached to the roots. Care must be taken to keep the root ball intact.

FIGURE 8–4 When cuttings are lined out in the nursery row, only one bud should be above ground level. At least one (preferably two) buds should be below ground level. (A) shows cutting directly after planting; (B) shows root development and initial top growth.

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S u m m a r y

Hardwood cuttings are an easy, inexpensive way to root some plants such as grapes. Rooting occurs outside or in a greenhouse and much of the work can be done in winter when more time is available. This method does not work well for many plants.

S t u d e n t A c t i v i t i e s

1. Visit a local nursery to observe a demonstration of hardwood cutting techniques.

2. a) Select at least one plant commonly propagated by hardwood cuttings. Perform the six basic steps to produce at least 10 cuttings.

b) Set up a calendar to determine

1. the storage temperature and dates to change temperature. 2. the approximate date for lining out certain cuttings.

3. inspection dates so that things such as moisture conditions, temperature, and rooting date can be noted.

c) Line out the cuttings in a nursery row in the spring and follow up to determine rooting success. Keep a record of observations, including dates when shoots and roots first develop.

3. Start a small nursery on the school grounds or at home in which to propagate and grow plants for future use. This is an inexpensive way to keep a supply of laboratory materials on hand.

4. Search the Internet using the following terms: asexual reproduction; stem cuttings.

S e l f - E v a l u a t i o n

s h o r t a n s w e r

List three differences between hardwood and softwood cuttings.

m a t c h i n g

Complete each statement on the left with the proper term on the right. Include both the letter and the word in your answer.

1. Ideally, hardwood cuttings are ______ long.

2. Hardwood cuttings are stored for the first 4 weeks at a temperature of ______.

3. Wood of ______ thickness makes the best cuttings.

4. Cuttings should not be sealed airtight because ______ would be excluded, causing rotting or even death.

5. After the first 4 weeks, cuttings are stored at a temperature of between _____.

6. A storage temperature of between 32 and 40°F prevents cuttings from growing ______.

7. A soft wound-healing growth called ______ forms on the basal end of the hardwood cutting.

8. It is best if cuttings are stored a minimum of ______ weeks prior to planting or lining out.

9. Cuttings are planted so that only the top ______ is above the soil level.

10. In any group of cuttings that are properly cared for, between ______ percent of the cuttings should root. (a) oxygen (b) 6 to 8 inches (c) medium (d) 2 (e) 32 to 40°F (f) bud (g) 6 (h) 60 and 80 (i) tops (j) 50 to 55°F (k) callus (l) 4 to 8 inches (m) moisture (n) 80 and 100 80392_08_Unit08_p102-106.indd 106 80392_08_Unit08_p102-106.indd 106 2/26/10 9:04:49 PM2/26/10 9:04:49 PM