Making Cuttings From Rhododendrons

PICK A SITE: Rhododendrons prefer a not-too sunny location; no direct sun in the hot part of the day as a general rule. The north side of a building or wall, a site in afternoon shade, or under 50% shade cloth or lath are usually good choices. Too dense a shade, however, will inhibit flowering. Plants in coastal locations that rarely, if ever, experience 100F days, can often tolerate full sun depending on the variety. Ask your nurseryperson how sun tolerant your variety is.

PLANTING: Follow the scheme suggested by the sketch above. Plant high in the ground. If you have poorly draining soil, skip the hole and plant in a pile of sawdust on top of the ground. Stake for support the first year. Some gardeners even grow their rhodies exclusively in containers as they are well suited for this. Rhododendrons are shallow rooted and want a light, loose planting media with plenty of tiny air spaces around their roots. We recommend a straight redwood sawdust or bark ("gorilla hair") as that's what we use at the nursery. No sand, no dirt, no potting soil or planting mix, and most importantly no fir sawdust; all of these tend to decompose too rapidly and turn the soil to "mush" (no air spaces). If you just can't resist, a little peat moss (up to 25%) can't hurt. Get yourself about 4 cubic feet of sawdust for each 5 gallon rhodie. Redwood sawdust is conveniently sold in compressed bales as "redwood soil conditioner" or "redwood mulch" at most nurseries and garden centers. It and redwood bark are much cheaper, however, when purchased from a bulk landscape materials supplier.

WATERING: Because of their shallow root system and airy soil requirement, rhodies should be watered lightly and frequently, not deeply. We water every other day in hot weather and maybe once or twice a week in cooler months. A plant in a container will want water more often than one in the ground. You should always be able to feel moisture just under the soil surface when you scratch with a bare hand. Good quality (low conductivity) water is important; if you suspect your water is too "hard", leach your plant once or twice monthly to keep the root zone "salt" level as low as possible. Don't use "softened" water however, as it just contains a different set of "salts" than does "hard" water. Be careful that a newly planted rhodie is still getting water into its root ball and not just the surrounding sawdust; drip the hose right at the base of the trunk if it begins looking wilty Also watch out for long interruptions between rains in winter months.

FERTILIZING: Get yourself a box of acid plant food or rhododendron, azalea, camellia food and follow the directions on the box. There are fancier other ways but this is the simplest and is certainly adequate. The box instructions are not usually written with California gardening in mind, so "cold weather" pre-cautions don't really apply to most of us; keep fertilizing at a much reduced rate right through winter.

PRUNING: Rhodies lend themselves nicely to pruning for size and shape. Always prune back to the outward side of a growth node; new foliage buds should break from the old wood just below your cut. Pruning should be done in spring or summer while there is still time for new growth to sprout and harden before cold weather.

MULCHING: Once a year spread a new layer of redwood sawdust or bark 1-2" thick inside the drip line of your rhodie. Pine needles work very well for this also. This much conserves root zone moisture and replenishes that material which has decomposed over the last year.

PROBLEMS:

- No Flowers - too much shade or too little fertilizer

- Leaf Burn - Marginal burn is from poor water quality or (rarely) too strong on the fertilizer; try leaching. Burn in the center of the leaf is sun scorch.. Both these conditions are made worse by too dry a root zone. Some varieties are more susceptible than others.

- Insect Pests - In recent years foliage thrips have become a serious rhodie problem. Thrips form colonies on shady lower leaves and their damage is seen as a silvery or grey mottling on leaf upper surfaces. They can eventually kill your plant if ignored. We recommend spraying Orthene in two application 2-3 weeks apart midsummer for best control. Other pests include: snails eating flowers, caterpillars and katydids eating soft new leaves, and sometimes aphids get on newly emerging leaves and stems but don't seem to do much permanent damage. Hand pick snails, caterpillars, and katydids; spray for aphids if they bother you.

- Diseases - Root rot is by far the most prominent. Avoid soggy root conditions; plant in coarse redwood sawdust or bark and mulch yearly. A plant that is "sinking" into the ground or its container because of decomposition is almost certainly going to perish eventually.

- Die Back - Sometimes a shoot or even a whole branch will just die off (look for dull, wilted leaves). These must be cut back to healthy wood as soon as they are discovered. If allowed to progress too far, the whole plant can be killed.