Depending on when the first freeze reaches your area, the time to take hardwood cuttings has begun or soon will be here. Even in tropical zones, some evergreens and deciduous shrubs are best cloned from hardwood in winter while they are as close to truly dormant as they ever get. It seems to me that you who live in the temperate zones have it the easiest when it comes to working with hard wood. Here’s what to do.
After an early freeze or when the weather is as cold as you expect it to get, take cuttings from healthy plants. Most of the time we prize tip cuttings, but those are the least helpful here because they dehydrate quickly. Instead, select pencil-thick stems or canes and direct your attention to the bumps along its length. These are the nodes that push out leaves and can be persuaded to do the same for roots. Look at the stem and in most cases you will see where this year’s growth begins. It is usually slightly lighter in color than the wood behind it. That wood – below the tip and above the very mature wood – makes the best hardwood cuttings and often there is enough for multiple cuttings from just one stem.
This year I will be rooting roses and an old Pfizer juniper from hard wood. The first is a lark, since I root roses most of the year already. And I’m testing the theory that older juniper branches will root this way and produce larger specimens for a spot in the garden that I need to fill. One serious prerequisite for hardwood cuttings is getting the right strength rooting hormone for the plants and Hormex has both the information and the products you will need (http://www.hormex.com/products/rooting-powders/what-strength-should-i-use/).
Resources differ slightly on how best to make the cuttings from the selected wood. I was taught the way I’ll describe here and have used it successfully, but I’m sure there are other ways that work as well. Two factors play into my way, the need to keep the wood right side up and to create as big a rooting surface as possible. Hardwood forms roots after it makes callus. The more area that can form callus, the more space there is for roots so I cut the base of the wood on a diagonal about half an inch below a node. I make the next cut 3-5 nodes above and slice it straight across to keep top and bottom visibly different. Make 2-3 inch diameter bundles of cuttings of about the same size and taken from the same plant. As you bundle, dip each base in the appropriate Hormex Rooting Powder and secure the group with rubber bands or jute string. Add a nametag!
Now comes the fun part. If you live where the ground freezes, fill a box with damp vermiculite or sand and bury the bundles entirely. Store it cold but not freezing, such as in an unheated shed. In warmer climates, I can recommend 2 storage methods. Bury bundles in thin-walled plastic pots filled with damp sand and nestle the pots in a pile of leaves or a mulch bed on the north side of your house. Since my house is on piers, I slip them under it in the cold shade. Another approach is to dig a 6 inch deep trench and bury the bundles in damp sand or leaf mold there. I gave up trenching when I moved onto clay soil, but it works where conditions are better. A friend in Arkansas puts hardwood bundles into 5 gallon buckets of his garden soil and leaves them in the barn. However you do it, get the bundles into cold but not freezing conditions so they can form the wonderful callus that gives rise to roots.
Most books and articles say to wait until spring to take the bundles out of hibernation, but I do it at the same time I prune roses in February. Dig a shallow trench or half-fill quart size pots with good garden soil, dip each cutting in Hormex Liquid Concentrate, and plant each one so half its stem is above the soil. Remember as you space them that the stems will put out leaves as well as roots in this last phase of propagation. I put a dusting of leaf mold over the soil like mulch and the result is cuttings ready to root yet protected from wind. By fall or winter, the new plants are ready for the garden and it is time to start the process again.