Thrills, excitement, and dreams come true—that’s what is in store for the home gardener who decides to try his luck at making cuttings by the fog mist propagation method.
With a minimum of effort and equipment, he can produce any number of fine, sturdy little plants from the choice of trees, shrubs, and evergreens.
We did it last year using two old cold frames and an ordinary, standard-nozzle garden hose. And we were working under extremely difficult conditions, for where we live in St. Louis County, Missouri, the summer of 1953 was the hottest and one of the driest ever recorded.
Yet we ended the project with more plants than we could use ourselves, and the inventory of the results reads like a veritable Who’s Who of trees and shrubs.
With the easy, almost sure-fire fog mist method, we could use large, well-branched cuttings to have husky little dogwood and magnolia trees and fine, bushy yews, boxwoods, and azaleas.
By rooting large cuttings instead of small slips, saving between one and three years of growing time for many plants is possible. Furthermore, larger cuttings are sturdier.
They form exceptionally strong root systems and can be carried through the first difficult winter with less protection and care.
Constant Mist
Many years ago, “constant mist” was tried experimentally on greenhouse cuttings at Ohio State University, Columbus. Dr. L. C. Chadwick, professor of horticulture, rigged up a system of overhead pipes and nozzles for the greenhouse benches.
Thanks to the misty spray, he got a very high percentage of rooting even from such reluctant plants like hollies, lilacs, crabs, Leucothoe catesbaei, and Viburnum burkwoodii.
The success of his experiments eventually resulted in various systems of “fog mist” propagation. By substituting water for shade, cuttings can be given ample sunlight. The cool, misty spray protects leaves from burning and keeps cuttings from wilting.
The unbeatable combination of ample sunlight and ample moisture produces almost magic results.
The leaf factories of cuttings can use the full power of sunlight to manufacture food needed for the difficult task of forming a new root system. Moreover, an abundance of water also seems to stimulate root formation.
Fog Mist Cuttings
Fog mist cuttings are remarkably vigorous and practically free from disease. In other years, when we used heavy shades or “sweat boxes” of greenhouse sash, we found it a ticklish problem to maintain a high humidity without encouraging various roots and leaf spots.
At one time, we used a fermate dip to control the diseases that attacked our azalea cuttings. The dip seemed helpful, but it interfered with rooting.
Open sun, plus the air-conditioning effect of a cooling spray, provides ideal growing conditions for the cuttings and, luckily, makes a very hostile environment for most plant diseases.
Injurious fungi and bacteria like high humidity but also need high temperatures and darkness. In extremely hot weather, we were careful to stop spraying in the late afternoon to give leaves a chance to dry out thoroughly before nightfall.
Since cuttings made by the fog mist method do not wilt, it is possible to make cuttings in early summer from deciduous trees and shrubs such as dogwoods, magnolias, and viburnums.
Pliable young shoots that can be rooted early in the season become downright obstinate if allowed to grow until late summer. Furthermore, cuttings rooted early in the season can grow and harden a bit before the first severe freeze.
Slips can be taken from deciduous trees and shrubs just as soon as new growth has firmed up enough to have a little body.
However, extremely young growth will not be satisfactory, for very soft, tender stems, and leaves contain too much nitrogen. Sappy little shoots lack the vigor needed to form good roots. They make spindly little plants.
Proper Timing is Crucial
Although it is important to take cuttings when a tree or shrub is at the proper stage of development, proper timing is not such a critical factor when the fog mist method is used.
Some accommodating plants, like Euonymus kiautschovicus or E. fortunei, can be rooted almost from April to October.
On the other hand, the rhododendron is a miffy prima donna that is most particular about timing. We rooted about 75 rhododendron cuttings, the part taken on August 15 and the rest from one to two weeks later.
Pinch Terminals In Early Summer
For best results with rhododendrons, magnolia grandiflora, and some other plants that develop tough stems, it is advisable to pinch off a few terminals (or end) buds in early summer. This encourages the growth of numerous young side shoots that make fine cuttings in mid-August.
Since there is very little information on plant propagation that can serve as a reliable guide for the home gardener, we did quite a lot of trial-and-error experimenting.
Among cuttings taken from July 1 to 10 that rooted well were dogwoods, azaleas (old and new wood), Magnolias soulangeana, liliiflora nigra, and grandiflora.
We were not as successful with white redbud or deciduous azaleas. Perhaps these plants would have responded better if we had taken cuttings two or three weeks earlier.
In Mid-August
We filled the frames with a variety of evergreens: yews, metasequoias, leathery viburnums, Pieris japonica, Pachystima canbyi, various kinds of boxwoods, and about a dozen kinds of hollies.
More than half of these cuttings were potted up in September, but some were left to winter in the frames. Hardy cuttings can tolerate a lot of colds, but during the winter months, we added lath shades to protect the evergreens from winter burn.
We quit using the “constant mist” when cooler weather came in early autumn. Frames were watered occasionally since the cuttings must never dry out.
Different plants have different timetables. Allowances must also be made for climatic variations. Here, near St. Louis, we can take cuttings at least two to three weeks earlier than in Chicago or Des Moines.
Experiment With Rooting Powders
We also found it necessary to experiment with rooting powders of various strengths. For tender little tips of azaleas, dogwoods, Pieris, and pyracantha (and also for roses), we used either Rootone or Hormodin No. 1.
We tried Hormodin No. 2 and 3 or Rootone’ 10 for heavier branchlets and old-wood cuttings of azaleas.
Hormodin No. 2 works well with euonymus and Japanese hollies, but we always used No. 3 on yews, boxwoods, rhododendrons, and larger cuttings of magnolias.
If there was any doubt, we treated the cuttings with the weaker powder since the synthetic hormones are toxic to many plants. We often tried powders of different strengths on two or three lots of cuttings from the same plant.
Preparation of Frames
The first step in preparing frames is to provide rapid drainage for excess moisture. Cuttings that stand in pools of water will suffocate for lack of air. At the bottom of each frame, we used a 4-inch layer of coarse cinders topped with about 2″ inches of sand.
In the smaller frame, we used an 8-inch layer of sand and Canadian peat (50 percent of each by volume) as the propagating medium.
Since we wished to experiment, we divided the larger frame into three sections for three different mediums: sand and peat, vermiculite, and pearlite. Pearlite is an expanded volcanic lava sold for horticultural use as “Krum.”
We tried to put an equal number of cuttings in each medium. All of the cuttings rooted very well, but many of the more difficult rhododendrons and dogwoods, for example-showed, a decided preference for the pearlite.
Although cuttings can be taken from the frames as soon as the first tender rootlets appear, we prefer to give them a chance to develop a strong, extensive root system. We, therefore, pot them up in a light soil mixture, covering the roots with a sandwich layer of vermiculite or pearlite.
This protects the brittle roots from injury and lets them take their time about pushing out into the soil. The plants seem to prefer this gradual transition period to the abrupt shock transplanting usually entails.
Potted Cuttings
Potted cuttings must be pampered a bit in hot, dry weather. The dogwoods were particularly resentful when moving from the cool spray into the arid August heat. We grouped the pots beneath lath shades and cooled them off with occasional shower baths.
Although cuttings can be wintered in pots, we had fewer losses than those transplanted into a little nursery bed.
We mulched these little plants with a heavy layer of manure or leaf compost topped with airy dry leaves or marsh hay covering. A whiter shade of laths or evergreen boughs is also desirable.
It sounds like incurable optimism to admit that we are still making cuts like mad, even though we may be going into our third straight drought year. In April, we rooted quantities of Vinca minor alba—we like this white form—and the Missouri Botanical Garden’s wonderful Bulgarian ivy.
By May 1, the frames were again filled with various kinds of euonymus, Korean boxwood, yews, and Ilex crenata convexa — all dividends from early pruning.
There’s a rainbow in that spray!
Images:
Wounding stem (using a very sharp knife to slit skin or outer layer of bark) helped some plants root faster; helped rhododendrons and magnolias develop heavier roots. Cuttings will not root at all, however, if the cut is so deep that it damages the inner woody tissues.
Until they were safe in a cold frame, the author protected cuttings by keeping them cool and moist on a cushion of damp sphagnum moss in a wet-burlap-lined carton or (right) in a plastic bag in which ice cubes were placed. The model in these photos is the author’s daughter.
Cuttings were prepared, a few at a time, in a cool dark basement. A pet way of propagating double white dogwood was to make heel cuttings by pulling a branchlet from the stem, as pictured here. “Water shoots” pulled from tree trunks are also rooted easily.
Cuttings, in a sharply draining frame, were bathed in the constant mist that acted as a gauzy curtain against the sun and so reduced shock and prevented wilting. By this method, it is possible to take cuttings earlier in the season and to root difficult trees and shrubs.
Cuttings may be lined out in a cold frame or a bottomless wooden box. A layer of sand and cinders 6 inches or thicker must be laid beneath that bed to drain quickly. Then a 10-inch layer of a rooting medium, such as perlite or sand
The author made cuttings during a prolonged drought in the hottest summer on record. When cuttings showed leaf burn, she covered the cold frame with a lath screen propped on an old glassless sash.
The author grew cuttings in pots for a few weeks before moving them to the garden. She placed sphagnum moss in the bottom of the pot and used one-third of each soil, peat, and (for azaleas) oakleaf mold. Pearlite or vermiculite was placed directly around the roots, as shown above. The Center photo shows cuttings in the ground being prepared for winter outdoors. Before the ground froze, a thick mulch of leaf compost was tucked around small cuttings and tossed over larger ones with a shovel. Tiny azaleas (as at right) were mulched with oak leaf mold and, in some cases, with a layer of pearlite, too. Often, to keep rabbits off and prevent burning and winterkill, flower pots were placed over the cuttings.
44659 by Eleanor Mcclure