Cuttings and tissue culture are the best way to go to reproduce the exact plants that have been successful. There are two books that we recommend on plant propagation. The first is Plant Propagation Made Easy by Alan Toogood from Timber Press. The second is The New Seed-Starter’s Handbook by Nancy Bubel from Rodale Press. For both softwood and hardwood cuttings we recommend using an organic potting soil that has had extra volcanic sand or other coarse textured pieces added for increased drainage. One of the successful tissue culture operations in Texas is Magnolia Farms in Houston.
Many herbs, annuals, perennials, vegetables, and even tropical plants can be started from cuttings. Take them when the plant is actively growing for best results. Water the plant a few hours ahead of the time you plan to take the cuttings, so it will be full of water. Cuttings from young plants may be taken anywhere there are sprouts long enough to be removed. If the plant is old, choose a young sprout. Herbaceous cuttings are usually from three to six inches long. A smooth, clean cut will form a callus and heal better than a ragged one. Cut the bottom end on an angle to allow more surface area for rooting. Pinch off all flowers, flower buds, forming seeds, and all except two to four small leaves before inserting it in the medium.
Insert the cuttings into a moist, well-drained rooting medium, such as damp granite sand or a combination of granite sand, coconut fiber, and fine textured compost. A mixture of peat, compost and volcanic rock powders or sand is also good but peat moss is expensive and antimicrobial.
A fleshy growth will form on the cut end of the cutting. This is the healing over of the cambium layer and called callus. It often, but not always, precedes rooting.
Most cuttings should be stuck into the medium as soon as they are made, so they won’t dry out. A blunt pencil or a dibble is a handy instrument to make a hole for inserting the cutting. Don’t insert the cutting before making a hole first, or you may bend or damage the cut end. Insert the cutting upright so the bottom end is about one inch below the surface of the medium. Keep the medium moist, but not wet, provide a temperature of 70 to 80 degrees F., and keep the cuttings out of drafts.
Plants with heavy, sticky sap content such as geraniums, pineapples, cacti are less likely to rot before they root if they are spread out on newspapers in the shade and allowed to dry for a few hours before they are inserted in the rooting medium.
Cuttings can be treated with rooting hormones first, but it’s not essential. Homemade rooting hormones can be made from natural apple cider vinegar in water or willow water, which is made by soaking 6-8” willow stems in water overnight. Human or animal saliva works even better.
Many plants can be started from cuttings. Most groundcovers, vines shrubs and perennials are started this way. Most trees are now started from cuttings to give true genetics to the new plants. As apposed to starting plants from seeds, each of the new plants will be genetically identical to the mother plant. "Hardwood" cuttings are taken during the winter dormant season. "Softwood" cuttings are taken from succulent new growth in late spring. "Semi-hardwood" cuttings are taken from partially matured new growth in the summer. Timing will depend on the type of plant being rooted. Cuttings should be 4 to 8 inches long, depending on the plant. They are best taken from the youngest growth s of healthy, vigorous shoots. Strip the leaves off the bottom 60 - 75 percent of the cutting. Some species root easier if the cuttings are wounded by removing two thin slivers of tissue on opposite sides of bottom of the cuttings. Some recommend dipping the cuttings in rooting hormone powder or willow water. Asprin dissolved in water has been reported to work. Our tests have shown that most of these are not really worth the trouble on most plants. What does work, believe it or not, is saliva. Unless working with a poisonous plant, stick the base of the cutting in your mouth. Stick the cuttings into pots or flats filled with some type of rooting medium- peat moss and perlite, sand, compost, etc. The best medium for propagating most plants is a compost-based potting soil.
Keep the cuttings warm and moist and in bright light until they form roots. It usually helps if you cover them with clear plastic such as dry cleaners' bags to keep the humidity up. It will help greatly if you have a greenhouse with a mist system to maintain 100 percent humidity. Cuttings will root in 2 to 8 weeks, depending on the species, at which point you can dig them carefully and pot them individually.
Softwood Cuttings - Softwood Cuttings, “slips” or “greenwood cuttings” are taken from vigorous, growing plants at a stage when the stem breaks with a snap when it is bent. Young, healthy, vigorous plants provide the best cuttings.
Late spring and early summer are the best times to take cuttings. Plants are making their fastest growth at that time, and the potential for root growth is the best. No cutting should be allowed to completely dry out, but softwood cuttings are especially perishable. They are best taken in the cool morning, and kept in water for a half-hour or so, before they are stuck into the medium.
In making a softwood cutting, cut it from the plant at an angle, rather than straight across. Softwood cuttings six to ten inches long root better than three or four inch long cuttings. More serve energy is stored in a larger branch, which aids initially in fast, heavier rooting, and better growth once rooting has occurred.
Herbaceous Cuttings – Geraniums and many other house plants and perennials, as well as some annuals are propagated by herbaceous cuttings. The cutting should be made in the spring through summer. They are usually 2”-4” long cut diagonally at the end just a little below a node and plunged in cold water for half an hour unless a milky juiced cutting or a geranium. Put under glass or plastic after placing in the propagation medium.
Leaf Cuttings – Many house plants can be propagated by merely starting leaves, with or without the leafstalk. Plants such as the African violet, sedums, hens and chickens, artillery plant, and peperomia can be started by simply cutting off a leaf with its stem attached, and burying the stem in a propagation medium.
Long, narrow leaves such as those of the sansevieria may be sliced into one to two inch pieces and stuck vertically in the medium. Keep the pieces top side up.
Hardwood Cuttings – From deciduous woody plants, are hard to root unless kept under mist spray. Hardwood cuttings are taken when the wood is dormant. Because these cuttings require very little equipment, it is convenient for home gardeners. Grapes, willows, spireas, cotoneasters, shrub roses, hydrangea, honeysuckle, mock orange, and numerous vines, can be started from hardwood cuttings. Take cuttings anytime from early spring when buds are beginning to open.
Malcolm Beck accidentally discovered that grape, especially mustang (Vitus rotundifolia), rooted best if cuttings were taken in early spring when buds were breaking pink. He suggested this to a vineyard operator who tried this and he got his best rooting rate ever. Howard experimented and discovered the same with grapes and figs but other types of hardwood cuttings didn’t work as well when taken at bud break. This is when the most energy is in the buds and tip growth of the plant. Select only healthy wood that grew the previous summer. Cut the top end on a slant, slightly above a bud. Cut the bottom end on a slant also, to expose more cut area to form roots. Make all the cuttings of each variety the same length, between five and twelve inches and tie them in small bunches. Bury the bundles in slightly moistened sand or vermiculite and store where they will stay cool but won’t freeze. By spring, the cuttings begin to from a thick callus on their bottom ends. Dip the callused ends in a rooting powder or soak in willow water and plant them in light, rich soil in a protected spot with morning sun and afternoon shade. As soon as the roots have started, give them some liquid natural organic fertilizer such as Garrett Juice.