“Propagation 101” ~ A short, comprehensive guide to starting plants from seed, tip cuttings, hardwood cuttings, softwood cuttings, soil layering and air layering
Certain seeds, like petunia and geranium, are notoriously slow to germinate and progress toward maturity at a veritable snail’s pace. A quick check on the seed packet, in the seed catalog or with the garden center staff, should reveal which seeds require an early start.
Containers: Plastic trays, fitted with inserts are ideal and allow each plant an individual compartment in which to mature. Some plants benefit from transplanting, once or twice, getting progressively stronger. For these, broadcast in a flat and transplant when the first “true” leaves appear (first set are generic looking seed leaves). Handle seedlings by the leaves, to avoid crushing delicate stems. Peat cubes, pellets and pots, along with small plastic pots, round out the container selection, which is based upon your own preferences. Soil: At least for the first phase, choose a soilless seed starting mixture of peat, vermiculite and perlite. Later, transplant to a light blend, which includes all of the above, in addition to an organic base (usually decomposed bark). Finely milled sphagnum moss is ideal for lightly covering the sown seeds, lessening the chance of damping-off.
Water: Tepid water, allowing the filled inserts to absorb water from the bottom until the top surface is dampened - drain excess water from the tray, immediately. As seedlings progress, light, topical watering may be preferred. Light: With very few exceptions, light is not critical for germination, but bottom heat is... which is why many of us place our covered seed trays (I lay folded grocery bags across them) atop the fridge and let the “free” heat circulate up around them, to hasten germination. Keep them lightly damp and check frequently, uncovering the flats and moving them to a light source, as germination commences. Thereafter, a sunny, south-facing window (near a source of bottom heat, if possible) will suffice, as long as the trays are turned 180o each day, to prevent leaning and stretching. Alternatively, a hooded fluorescent fixture, equipped with grow bulbs, wide spectrum or cool white bulbs (a combination of 2 different types usually works well) should be maintained at a distance of 3-4" above seedling tops. Raise the fixture as seedlings progress, maintaining the same distance.
Bottom Heat: Thermostatically controlled heating mats, that accommodate from 1-4 seedling trays, are widely available to hasten the germination of seedlings or the rooting of cuttings.
That’s a quick, thumbnail approach to seed starting. The garden center staff is just a phone call away, should you have cultural questions or product inquiries. The seed racks await your perusal!
Propagating the Indoor Oasis... Air Layering ~ a useful technique, for indoors or out! Depending on your locale, you may very well be engaging in the first gardening chores of the season, while continuing to tend that indoor oasis. It's often at this point, that overgrown indoor specimens demand our attention.
Rather than severe pruning that leaves unsightly stumps, or treating such large-scale prunings as cuttings (a risky proposition, at best), consider performing an air layer. While some of the larger foliage plants with which we accent our home interiors, may have become overgrown and leggy, this becomes the ideal way to handle the pruning. At the same time, we gain a young, healthy, well-rooted plant to add to our collection or give to a gardening friend.
An air layer is a method of inducing the top portion (one or several stems may be air layered at the same time) of the plant to produce roots, while still receiving sustenance through its root system. Suitable specimens for this method of propagation are schefflera, dracena, yucca and ficus, including weeping fig and rubber plant. At a point where the main stem is still somewhat green, usually about 10-20 inches back from an actively growing tip, is the best place to attempt an air layer. Select an area immediately below a leaf or leaf scar. Place a small bamboo stake (about one foot long) alongside the area to be cut and secure it, above and below, with twist ties. This will act as a splint, preventing the air layer from snapping off before it's rooted.
The materials you need for this operation include long-fibered sphagnum moss (soaked in warm water), rooting hormone powder, artist's paint brush, a sharp knife, plastic wrap and more twist ties. Make your incision, at the aforementioned point, along the stem. There are two acceptable methods of cutting into the stem. Girdling the entire stem, by cutting into the inner wood, will often stimulate root production. The other way, which I've found most successful, is to cut out a notch on one side of the stem, which extends about 1/3 of the way into the inner wood. This becomes a very weak point, which is why that "splint" was so important.
With a small brush, dust the cut surfaces thoroughly with the rooting powder. This will hasten root production and guard against possible fungus problems. After wringing excess moisture from the long- fibered moss, pack it into the cut and form a ball of sphagnum around the area. Wrap the ball with plastic, tying off above and below with twist ties.
Check the moss several times weekly for moisture, sprinkling lightly, if needed, then replacing the top tie. After about six weeks, you should notice small, white roots expanding into the moss ball. Your new plant should be ready to stand on its own. Sever it just below the moss, remove the plastic and pot it in a loose, well-drained potting soil, adding a small stake for stability.
The stump you leave behind can be re-trimmed to a more appropriate point, just above a leaf or leaf scar, from which new growth will eventually emerge. December-March are ideal months to attempt an air layer. If you wait until indoor plants become more active, in April/May, the incision may heal over quickly, without ever producing roots. I've experienced this several times, while trying to root a rubber plant.
By making an incision, you literally shock the plant into trying to propagate itself, and so, roots are produced. While actively growing, the sap flows freely and the plant's ability to heal a mechanical injury is greatly increased; hence, the increased failure rate of air layers performed on indoor plants, during the growing season. However, an air layer can be a very successful way of propagating some of our woody ornamentals in the spring... rhododendrons and azaleas respond well.
Soil layering ~ A propagation technique that happens naturally, as the low, bottom branches of forsythia, rhododendron, holly and other specimens come in contact with the soil... every gardener has witnessed this natural phenomenon. Take advantage of this common rooting tendency, performing soil layers throughout the landscape to propagate favorite plants. The advantage of this technique, as well as the above air layers, is that the minimal shock involved - water and sustenance still reach the prospective new plant, all during the rooting period. A trowel, sharp knife and weed fabric pin are the only accoutrements you need for this propagation project.
Tip Cuttings ~ Normally we harvest the top 3-5” for cuttings, making a sharp diagonal cut, just below a leaf node. (Re-cut the remaining stems of the stock plant, at a 45o angle, just above leaf nodes.) After trimming off excess foliage, dip each cutting end in rooting hormone (Rootone, Hormex, etc.), shake off surplus powder and insert into rooting medium. Geraniums and certain fleshy-stemmed cuttings require callusing for 8-10 hours, before insertion into medium. Rooting medium may consist of perlite, vermiculite, milled sphagnum moss, very well-drained soilless mix, sand, or some combination thereof. It depends on the plant’s natural preference, as well as the gardener’s individual success record with various mediums. Hasten the rooting period by employing a seedling heat mat. Tent plastic, or use a high plastic dome, to recirculate humidity (be sure to provide ventilation)... keeping the cuttings evenly moist. Bright light, but no direct sun during this period. Pot up rooted cuttings, moving slowly from one pot size to another. Rose and mum cuttings can be rooted right out in the garden, in spring - summer!
Leaf Cuttings ~ An easy way to propagate succulents, hens and chicks, Christmas cactus, African violets, etc. Begonia leaves are laid across the medium and pinned to the surface, before slicing their veins... you’ll have a new plant at nearly every incision.
Hardwood cuttings ~ A reliable method of propagating deciduous shrubs and vines. Cuttings are harvested at the end of the season, after the first night that temps dip down to freezing. One branch will yield multiple cuttings... the tip, plus current season’s growth. Obviously, the close-set buds of a forsythia branch will yield more cuttings than a grapevine, with its widely spaced buds. Depending on the species you’re propagating, cuttings will be about 6-8” long.
Make a flat cut just below the base of a dormant bud and an angled cut about 1⁄2” above a dormant bud... water will be shed from the angled cut in the future and you can easily differentiate between top and bottom. Cutting just below a node causes callousing and more reliable root formation, subsequently. Dip the bottom ends of all your cuttings in the appropriate rooting hormone. Bundle them up, with butt ends even, tie together and bury upside down in a 10” deep hole. This prevents them from sprouting over the winter and the sun warming the soil above the bottom ends is helpful in callous formation.
Wait until all danger of frost is past, before unearthing and planting out your cuttings. Buds will be swollen and tender, so use care during this process. Dig a trench in a sunny, well-drained area in fertile garden soil, and place your cuttings about halfway into the trench. Leave about 2-4 buds above the soil, backfill the trench and tamp the soil. Keep your cuttings evenly moist during their rooting-in, but avoid over-watering. They’ll produce foliage during the growing season, as they continue to develop roots. Your rooted cuttings can be moved after they go dormant in that first fall, or moved the following spring before they break dormancy. Alternatively, follow the instructions up to the point of bundling and line them out in a trench that first fall. As long as you can dig, before the ground freezes, you can continue harvesting and burying or directly planting those cuttings.
Softwood Cuttings ~ Usually wood is harvested during June and July, and sometimes into August. We are looking for semi-ripe wood... old woody growth is difficult to root and tender, new spring growth usually rots before it roots. If it’s green and bends, the stem is too young to root. If it’s woody, it will not bend. The semi-ripe wood we’re looking for will actually snap when bent and has entered the desirable softwood stage. Harvest the top 3-5” for cuttings, making a sharp diagonal cut, just below a leaf node. (Re-cut the remaining stem, at a 45º angle, just above a leaf node.)
After trimming off excess foliage, dip each cutting (butt end) in rooting hormone, shake off surplus powder and insert into rooting medium. Bottom heat (provided by a seedling tray heating mat), and high humidity (tent plastic wrap or employ a vented growing dome, or use a mist system) are essential to success with softwood cuttings. They will normally root in about six weeks.
Note: During March, we give an indoor start to broccoli, cabbage, cauliflower, Chinese cabbage, lettuce and peas. This is the month, also, for transplanting broccoli, cabbage, cauliflower, celery and lettuce. Things to consider? Raised beds warm up sooner in spring, their height making planting and maintenance easier on the gardener. When space is limited, trellis vining veggies and/or grow them in containers…look for an ever-increasing array of bush veggies like squash, cucumbers and eggplant.
“Corliss Culture Sheets “ written by Deb Lambert for Corliss Bros. Garden Center & Nursery - 31 Essex Road
(Rte.133) Ipswich, MA 978.356.5422/ www.corlissbrothers.com