Taking Cuttings
Cuttings provide a cheap and often easy method of reproducing a desired specimen: a certain shrub or favourite rose. However, the new plant is a clone of the first, is genetically identical, and shares the same weaknesses and strengths of the original plant. Thus, your rhubarb or rubber plant may be identical to your neighbours', and importantly, can be equally susceptible to the same problems.
This section covers general principles for taking cuttings.
Growing from cuttings is easiest for non-woody plants. Deciduous trees and shrubs are also fairly easy in spring; hardwoods and some evergreens may prove difficult.
Most plants are reproducible in this manner, though some coaxing may be needed. Plants that have been pruned in the previous growing season produce the most vigorous shoots and are most likely to root well. Rooting hormone can significantly aid with difficult plants.
Use only new growth from young specimens, if possible. Plants should ideally be pruned back the previous fall, so that the new, healthy and very vigorous stock may be used as material for cuttings. Use a sharp, clean knife. Keep cuttings moist and cool until ready to pot up, and ideally take these in the early morning, an hour or two after watering.
Softwood cuttings taken in the spring usually work best; plant immediately. Grow in good indirect light, temperatures of 60-80F/15-27C, and in a humid atmosphere: mist frequently, or enclose the pot in a plastic bag, allowing it to breathe several minutes daily. Bottom heat may help.
Semi-hard or semi-ripe cuttings are taken from mid-summer to early fall, and are harder to grow, but share the same requirements.
Hardwood cuttings are taken at the start of the dormant season, when leaves have dropped, and as such, humidity is less a priority. These are often overwintered in a cold frame, with new growth expected the next spring.
Grow cuttings in a rooting medium consisting of well-draining soil or peat mixed with sand, perlite or vermiculite. Peat mixtures especially will be sterile and protect against disease. Cuttings, especially if harder to root, may be tied into small bundles prior to planting. Protect, and watch for fungal infection.
Inspect regularly for growth, and pot up into small pots. Rooted specimens should resist a gentle tug; if not yet rooted, stick back into the medium. Remove and discard rotting specimens.
Some cuttings will even root in water (plant up if roots are 1" long), or reproduce by runners which may be rested onto fresh, moistened compost until the new plantlets grows roots, after which they are severed from the parent plant.
Sowing Seed
All seeds may be sown outside in late spring, or started earlier indoors. Hardy trees and shrubs, perennials and bulbs may also be sown in fall; cold will assist in germinating these. Houseplants can be sown any time of year, though ideally in spring or early summer for most rapid growth.
Note that many seeds have specific germination requirements: special tricks are described below, and the needs of many species are described in the alphabetic listing. Make sure you have ample seed if using trial and error.
The following table suggests general germination temperatures for various kinds of seed. Note that the requirements of individual species may vary considerably: do not commit all your seed to any trial of germination. More specific information is given under individual plant listings.
type of plant typical germination temperature
cool temperate perennial 55-65F/12-18C
temperate trees and shrubs 55-60F/12-15C
warmer perennial 65-70F/18-21C
tropicals, including trees and shrubs 70F/21C
garden vegetables 70-75F/21-24C
Ideal temps are given, though I've easily germinated plants expecting 80F/ 27C in 65F/18C conditions. However, expect slower germination, a lower percentage of germination, or both at less-than-optimal temperatures. Also, seedlings are more likely to do poorly with temperatures that are too high than too low.
Use a sterilized growth medium of some sorts, the finer, the better. For example, mix sterilized soil with equal amounts of peat and fine vermiculite or perlite, for a good starter medium, or use some other mix as described under Growth Media.
Potting soil itself may be too rich in nutrients and can actually damage seedlings. Still, many people use such soil, often without obvious penalty. If a soilless mix is used, then feeding with fertilizer, fish emulsion, or similar is required once seedlings reach the two-leaf stage.
Level soil without compacting it. Dustlike seeds are left uncovered: mix these well with a larger quantity of sand to spread them easily and evenly. Fine seeds are covered with a fine of layer of soil. Otherwise, bury once to twice the depth of the diameter of the seed.
Conventional wisdom held that most seeds prefer to germinate in the dark, and seeds are often covered for that reason, though most will germinate in light or dark. Ideal is subdued indirect light, unless otherwise specified. If germinated in the dark, uncover with first germination, and expose to air.
Initially, plant into already somewhat moist (not wet) soil, and where possible, water from below, by standing in tray of water for 20 minutes. Use plastic bags tented over the pots, or specially-designed propagaters, to prevent moisture loss by evaporation, watching that the sun does not bake seedlings in this enclosed environment. Use wicking systems as a good alternative method of providing water.
Humidity is also needed for germination; about 50% works well. Too much moisture, however, encourages damping off, an often lethal fungal infection. Be careful, and uncover seedlings immediately with the first germination. From this point on, use a small fan to provide gentle air circulation directly to the seedlings, to help prevent fungal problems, and also build sturdier plants.
Soil warmth often greatly helps germination: set seeds above the fridge (if light is acceptable), on a heating pad, or use temperature-adjustable soil heating cables. Note that moist soil is cooler than the ambient temperature.
Good light is required, i.e. a south-facing window, greenhouse, or proper artificial lighting. Provide at least 14 hours of good light a day, and if used, keep fluorescent tubes as close to the plants as possible.
Prick out seedlings into individual pots when the first true leaves have appeared and they seem robust enough. Handle gently by their leaves, not stems. Free roots without traction, make a hole in new, moist compost with the butt end of pencil and lower in place, then firm around. Young seedlings may benefit from a mixture of soil, compost, optional vermiculite and bone meal.
Keep cool at 65F/18C, in good indirect light. Perennials especially prefer cooler temperatures, down to about 40F/4C at night. Water lightly, from below or with a fine mist. Give seedlings plenty of room to minimize the number of transplantations; many plants should not be transplanted after this first move.
Feed seedlings after the second set of leaves has developed, with diluted 10-52-10 or 20-20-20 solutions, compost tea (if not too rich in nitrogen) or fish emulsion, or simply transplant into rich organic growth medium.
Plants destined for outdoors should be gradually introduced when the weather warms up: place in a protected spot for two hours one day, three the next, etc., and decrease night time temperatures gradually. This hardening off should take place over 1-2 weeks.
Fall-sown seeds can be started outdoors; for better protection in harsher winters, sow into a cold frame, in the shade. Always mark where sown.
For cacti, water from below after germination, especially if seedlings are very small, and allow to dry out between waterings. Bottom heat and warm ambient temperatures, 75F/24C daytime, 70F/21C at night, ideal. Seed and young seedlings should be protected from the midday sun.
Do not prick these out until the second year after sowing, when bodies are some 1/4" thick, and distinct roots and spines have formed. Succulents grow much quicker and may be transplanted within weeks or months.
Transplant into light, porous medium, being careful to protect the tender roots. Long roots may be trimmed but roots should never be bent; the neck of the roots must be at the soil surface. Water for several days after transplanting; transplant only during the growing season.
Bonsai-destined seedlings are sown into gritty well-drained compost, and usually grow faster, and are more vigorous, if these are started outside. Water several hours prior to transplanting.
Finally, many seeds go dormant if not sown immediately upon ripening. If unsure how to break dormancy, try several methods with each type of seed, using a small amount only. Often shiny hard coats need chipping or soaking, soft seed coats only stratification.
Dividing Plants
Division reproduces plants asexually, resulting in genetically identical offspring, with all the original desirable and undesirable attributes. Many plants naturally reproduce by division, some much more readily than by seed. It is also easy, and produces more mature specimens quickly.
Water plants well for the two days prior to dividing. This is best done in cooler weather or later in the day. Divide after the plants have finished flowering, or in spring, for fall-flowering species.
Knock plants from pots, or dig up, and pull the rootball into sections, each containing part of the crown and a few good roots to support it. The rootball often falls easily into a few discrete clumps: use nature to guide you. A knife or pair of pitchforks may be needed to separate tougher root systems, and with some plants, such as Astilbe, an old saw may be needed to cut them apart.
Both long leaves and long roots should be trimmed back, and dead or diseased parts of the clump discarded. Each new section needs both healthy roots and shoots. Replant immediately and water well, and protect from strong light and cold for several weeks.
Rhizomes or tubers can often be cut into pieces, each with one or more shoots, buds, or bud eyes. Replant, and protect several days. Suckers may also be cut or pulled off, each with a good root network, and should similarly be protected.
Plantlets produced on runners may be rooted while attached to parent plant, or be freed then planted into warm moist soil. Protect from sun for a week or two.
Layering
This technique basically consists of burying a section of a branch and allowing roots to form on the buried part, prior to severing the new plant from the parent. Select a young, healthy, low-growing shoot, ideally one pruned the previous season, and from early spring to mid summer, dig a shallow trench in well-worked, well-draining soil, to layer it into.
Remove side shoots and leaves from the branch, except from its very tip. Next, cut a small strip of bark, 2" long, from the branch some 10-12" from its tip, and brush with rooting hormone. Bend the branch into the trench and peg into place, taking care not to bend it so much that it will break. Bend the tip of the branch so that it points up out of the soil. Stake the tip in an upright position.
Note: while this is the recommended technique, often just bending the branch down and burying some part of its length will suffice to root this branch.
Keep the branch well watered until rooted, and sever from parent in autumn. Check late autumn or the following spring if good root development has taken place, the layer is ready for transplantation.
Grafting
Grafting is an old and well-established technique by which parts of two separate plants are joined and then grow into one. The lower part, called stock or rootstock, typically provides a hardier or more disease-resistant basis to the plant, or may limit the mature size of the specimen, while the scion, grafted onto the stock, consists of the desired fruit or flower-bearing portion.
Stock and scion must be compatible: unrelated plants cannot be randomly joined together. The closer related species are, the more likely one is successful. Thus, wine grapes can be grafted onto North American grape rootstock, multiple apple varieties onto one apple tree base, desirable tomatoes onto disease-resistant stock, even tomatoes onto their potato relatives.
Collect unfrozen, healthy scions, each 8 to 12" long, during the winter, a few weeks before grafting actually takes place. Store in the fridge, in damp peat moss and enclosed in plastic; soak a few hours before grafting. Then make fresh cuts to trim scions to their desired length; leave at least 4 buds. Don't touch the cut ends, and when grafting, ensure that the original orientation of stock and scion remains the same, that is, that up stays up, and down stays down.
A very sharp blade is used, so that plant tissues are cut, not crushed. For healing to occur, the cambium of the scion, a thin layer of plant tissue found just below the bark or skin of the plant, must be linked to the cambium of the rootstock; it is from this layer that the xylem and phloem, which carry water and nutrients, derive. Thus, the outer tissues of both plants must be lined up before being held into place.
Ordinary tape is as effective as anything else, in terms of holding scion and stock together, until the plant heals. However, enclosing the graft site in plastic may be helpful; it helps prevent the site from drying out. Remove tape once the scion shows signs of growing and the callus at the graft site seems to strain against the tape.
If moving a grafted specimen, make sure that the bud union stays at least 2" above soil level, so that the scion cannot itself grow roots directly into the soil. Should this happen, desired rootstock properties may be lost altogether.
Four techniques are described and illustrated in sketch form: bud grafting, whip grafting, side-veneer grafting, and cleft or wedge grafting.
Bulbs
Various techniques involving division of the actual bulb, may be used to propagate some of the species that grow from them, i.e. lilies, Alliums, Fritillaria, Hyacinthus, and others. Bulb scaling, bulb chipping, and twin scaling techniques cannot be used interchangeably: if in doubt whether a technique may be used, then consult the individual listings for more information. Also, do not commit all of your bulb material to one of these procedures, since success is never certain. In particular, fungus can easily ruin the experiment. | 
