Last month we discussed treating cuttings with growth regulators. This month we willn choose a few more plants to propagate but before doing that let's talk about "wounding" cuttings.

Root production on stem cuttings can be promoted by wounding the base of the cutting. This has proved useful in a number of species, such as Juniper, Arborvitae, Rhododendron, Maple, Magnolia and Holly. Wounds may be produced in cuttings of narrow-leaved evergreen species, such as Arborvitae, by stripping off the lower side branches of the cutings. (Illustrated) Stripping the basal leaves off a cutting has also been used as a method of wounding. The benefits of stripping basal leaves is species-dependent; (Berberis) and (Juniperus) cuttings benefit whereas (Spirea), (Forsythia) and (Weigela) do not. Stripping basal leaves of cuttings reduce the propagation bench space required for some species, allows the propagator more flexibility to work with different size propagules, may serve to improve the contact area between the cutting and media and can potentially improve absorption of rooting compounds. A common method of wounding - making a verticle cut with the tip of a sharp knife down each side of the cutting for an inch or two, penetrating through the bark and into the wood - may be ennough.

Larger cuttings, such as magnolias and rhododendrons may be more effectivelly wounded by removing a thin slice of bark for abour one inch from the base on two sides of the cutting, exposing the cambium but not cutting deeply into the wood. For the greatest benefit, the cuttings should be treated after wounding with one of the root-promoting compounds, either a talc or a concentrated solution dip preparation, working the material into the wound.

One type of wounding to avoid is accidentally crushing and damaging of basal cutting tissue with dull shears. It is from the basal tissue that both the flow of water from the propagation media must occur for cutting survival, as well as root initiation for regenerating new plants. Finally, always use sharp shears and periodicallly disinfect them.

Now that we have covered the topic of wounding, let's choose our plant of the month. This month we will learn the proper method of propagating (Holly) (Ile x spp).

Holly can be propagated by seeds, cuttings, grafting, budding, layering, and division. Most hollies are dioecious. The female plants produce the very desirable decorative berries if male plants are nearby for pollination. In seed propagation, bot male and femalle plants are produces in ratios of one female to three, or sometimes up to 10, male plants. Sex cannot be determined, however, until the seedlings start blooming, at 4 to 12 years.

Seeds. Germination of holly seed is very erractic; those of some species, I. crenata, I. cassine, I. glabra, I. vomitoria, I. amelanchier, and I. myrtifolia, germinate promptly and should be planted as soon as they are gathered. Seeds of other species, I. aquifolium (English holly), I. cornuta (Chinese holly), do not germinate until a year or more after planting even though stratified, probably due to rudimentary embryos at time of harvest.

Seeds of I. aquifolium, I. opaca, and I. cornuta should be collected and cleaned as soon as the fruit is ripe in the fall and then stored at about 40 C (400 F) until spring in a mixture of moist sand and peat moss. Germination in these species generally does not occur until a year later, and then growth is very slow, two seasons being required to bring seedlings of I. opaca to a size large enough to be used for grafting.

Cuttings. This is the method most used commercially, permitting large-scale production of choice clones. Semihardwood tip cuttings from well-matured current season's growth produce the best plants. Cuttings taken from flat, horizontal branches tend to produce plants having this type of growth and those from upright growth produce upright plants.

Timing is important; best rooting is usually obtained from mid- to late summer, but cuttings may be successfully taken on into the following spring. Wounding the base of the cutings helps induce root formation. The wounding induced by stripping off the lower leaves may be sufficient.

The use of a root-promoting chemical, particularly IBA at relatively high concentrations (8000 to 20,000 ppm), is essential in obtaining rooting of some cultivars, such as I. opaca 'Savannah' (10,000ppm IBA liquid), whereas 2500 ppm IBA is sufficient for medium-difficult species such as I. cornuta(15). I. vomitoria 'Nana' are direct stuck into 6-cm (2-1/4in.) liner pots using 3000 ppm K-IBA to spring-summer (Alabama) and 5000 ppm K-IBA fall-winter (62). Bottom heat at 21 to 240C (70 to 750F) is beneficial. The maintenance of a high relative humidity is essential. The use of intermittent mist in a greenhouse, where high temperatures can be maintained, provides good rooting conditions. A 1 perlite:1 peat moss or 3 pinebark:2 peat:2 perlite rooting medium is satisfactory.