Propagation: Growing New Bonsai from Seed, Cuttings and Air Layers

You don't have to buy every tree — you can grow bonsai material from a seed, root a snipped branch, or use air layering to turn an awkward branch (or an ugly tall trunk) into a brand-new tree with a ready-made root system and taper.

The main ways to make material

Each method trades speed for control:

Seed — cheapest and most plentiful, but slow: years before you have a workable trunk, and seedlings vary. Good for volume and patience, not for a quick specimen.
Cuttings — a branch rooted into its own plant; faster than seed and genetically identical to the parent, so you keep a good clone's traits.
Layering (air or ground) — rooting a branch while it's still attached to the parent, then severing it once rooted. The most reliable way to get a sizeable tree fast, and the only easy way to fix a trunk with no taper or no surface roots.
Grafting — joining tissue from one plant onto another, used to add a branch exactly where you need one or to put a desirable foliage onto tough rootstock. More advanced.
Nursery stock and collecting — not propagation, but the fastest routes to a thick trunk; covered in the buying guide and worth remembering as the shortcut.

From seed

Many temperate species (maples, pines, hornbeams) need stratification — a period of cold, moist storage that mimics winter — before they'll germinate; a few weeks to a few months in damp medium in the fridge is typical. Sow in a free-draining mix, keep moist and warm, and be patient. From day one you can influence the future tree: wiring a little movement into a young seedling trunk, or pruning the taproot early to encourage a flat, radial root base (nebari).

From cuttings

Cuttings work well for elms, junipers, ficus, willow, boxwood and many others:

Take a healthy shoot — softwood cuttings in late spring/early summer for many species, semi-hardwood later; some (willow, ficus) root almost regardless.
Cut just below a node, strip the lower leaves, and optionally dip the base in rooting hormone.
Insert into a gritty, free-draining rooting medium, keep humid (a covered tray or bag) and out of harsh sun, and don't let it dry.
Roots form in weeks to a couple of months. Pot on once they're established. Cuttings start with no taper, so plan to grow the base out.

Air layering — step by step

Air layering is the technique worth mastering. You induce roots on a branch or trunk section up in the air; once it has roots, you cut below them and pot up a complete new tree. Do it in the growing season when the tree is actively moving sap. The ring-bark method is the most reliable:

Choose the spot. Pick a point just below where you want the new tree's roots to emerge — often just under a nice branch structure, or partway up a trunk that's too tall and taper-less.
Remove a ring of bark. Cut two parallel rings around the branch about 1.5 to 2 times the branch's diameter apart, and peel away the bark between them completely.
Scrape the cambium. Scrape the exposed wood to remove the slippery green cambium layer entirely — if any is left, the wound bridges over and roots never form. This is the single most common failure point.
Apply rooting hormone to the upper cut edge, where the new roots will emerge.
Wrap in moist sphagnum moss. Pack a good handful of pre-soaked, wrung-out sphagnum around the wound so it fully covers the upper edge.
Enclose and secure. Wrap the moss in clear plastic film and tie it tightly above and below so it holds moisture and doesn't slip. Many growers add an outer layer of foil or opaque wrap to keep the roots dark and stop the moss cooking in the sun.
Keep it moist and wait. Check periodically and re-moisten if the moss dries. Roots typically appear in several weeks to a few months depending on species and season; you'll see them through the clear film.
Sever and pot. Once a healthy mass of roots has filled the moss, cut through the trunk just below the new roots, remove the wrap gently (leave the moss around the roots), and pot into a protected, free-draining container. Keep it sheltered and out of strong sun/wind while it establishes, then treat it as a young tree.

Ground layering

The same principle applied at soil level: wound or ring-bark the base of a trunk and mound free-draining soil over it, and a new, wider, radial root system forms above the old one. It's the classic fix for a tree with poor or one-sided surface roots — you grow a whole new nebari.

Grafting, briefly

Two techniques come up most in bonsai:

Approach grafting — a branch from one plant (or another part of the same tree) is held in contact with a prepared channel until the two fuse, then the donor is separated. Used to add a branch exactly where a gap needs filling.
Thread grafting — a whip of a shoot is threaded through a drilled hole in the trunk or branch and left until it unites, producing a new branch at a precise point.

Both are slower, season-dependent projects but invaluable for placing growth where pruning and wiring can't.

Which method, when

Want lots of trees cheaply and have patience — seed.
Want a faithful copy of a good tree, fairly quickly — cuttings.
Want a decent-sized tree with instant taper and roots, or need to salvage a tall trunk — air layering.
Need a branch or new roots in an exact spot — grafting or ground layering.

Pair this with the repotting and soil guides for aftercare of your new trees, and see individual species pages for which methods each tree takes most readily.

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