How to graft a pawpaw

Why graft a pawpaw

Pawpaws do not come true from seed. Plant a seed from the best fruit you ever tasted and you get a genetic one-off that may be wonderful, ordinary, or barely worth picking, and you wait 5 to 8 years to find out. Grafting sidesteps all of that: you take a small piece of a proven named variety and join it to a seedling or sucker, and the tree that grows bears that exact fruit, usually in about 3 to 4 years. It is the only dependable way to reproduce a specific pawpaw, which is why named varieties are always sold as grafted trees.

Rootstock: seedling or root sucker

A pawpaw can only be grafted onto another pawpaw. You have two choices of rootstock and growers genuinely split on which is better.

• Seedlings are the common choice and tend to give the higher take rate. A useful habit, and one Kentucky State's program recommends, is to raise seedlings from a known variety rather than random wild seed, so that if the graft dies the regrowth is still a respectable pawpaw and not an unknown.
• Root suckers can grow with real vigor once established, some growers report several feet in a season, because they sit on a mature root system. The catch is that a sucker must be cut free of its parent's lateral root and given time, ideally about a year, to build its own roots before you graft it. Graft a just-severed sucker and it often stalls.

Either way, aim for rootstock about pencil-thick where you intend to make the graft. See growing pawpaw from seed for raising your own rootstock.

Collect and store scion wood

Scion wood is the piece of the variety you want to propagate. Cut it in late winter while the tree is fully dormant, choosing straight, pencil-thick lengths of last year's growth with plump, well-formed buds. Seal the cuttings in a plastic bag with a barely damp paper towel to keep them from drying, label them, and store them in the refrigerator. The goal through spring is a dormant scion and an awake rootstock, so keeping the scion cold holds it back until you are ready.

When to graft

Graft in spring, once the rootstock is breaking dormancy and the weather is settling reliably warm, broadly mid spring into early summer depending on your region. The rootstock needs to be actively growing so it can heal the union, while the refrigerated scion is still dormant. Grafting too early, into cold or still-dormant stock, is a common reason unions fail to knit.

The techniques

Several grafts work on pawpaw, and choosing between them is mostly about how the scion and rootstock diameters compare. In every one, the thing that actually matters is that the green cambium layer just under the bark of the scion lines up with the cambium of the rootstock on at least one side, because that living tissue is what fuses.

• Whip-and-tongue. For scion and rootstock of about equal thickness. Matching long, angled cuts with an interlocking "tongue" give a large cambium contact area and a strong, self-holding join. The go-to for most bench grafts.
• Cleft. For a thinner scion into a thicker stock. Split the cut stock, cut the scion to a wedge, and set it to one edge so the cambiums touch. Forgiving and beginner-friendly.
• Bark inlay. For a scion much smaller than the stock, done in spring when the bark "slips" (lifts freely). Slit the bark, tuck a shaped scion behind it, and wrap. Widely used for top-working larger trees onto a new variety.
• Chip budding. A single bud, rather than a length of wood, set into a matching notch cut in the rootstock, typically in late summer. Economical with scion wood.

Whatever the cut, use a sharp, flat-ground grafting knife and make it in one clean pass. A dull or hollow-ground blade crushes the cambium and the graft fails before it starts.

Wrap, seal, and support

Once the cambiums are aligned, bind the union with a rubber band for steady pressure, then wrap the whole graft in self-sealing grafting film, a single layer over the buds so they can still push through. The seal keeps the union from drying while it knits, the single biggest controllable factor in whether it takes. On exposed or windy sites, growers often add a light stake or brace so a gust does not snap the fresh union. Remove the rubber band once the graft has callused, after roughly two months, so it does not girdle the stem.

Aftercare: the make-or-break weeks

A graft is not "set and forget." As the rootstock wakes it will try to push its own shoots, and every one of those steals energy from your scion, so rub them off whenever they appear until the scion is clearly growing. Watch the scion's petioles: leaves whose stalks stay green and then drop away cleanly are the sign the bud has healed and taken. Keep the young tree watered and, in deer country, caged, because a single browse can remove the whole graft. And do not let it fruit the first year, strip any flowers, so the union thickens before it ever carries weight.

Why grafts fail (and how to avoid it)

• Cambium missed. If the green layers do not meet, nothing fuses. Match at least one side precisely, and favor cuts that give more contact.
• It dried out. An unsealed or poorly wrapped union desiccates. Wrap thoroughly and re-wrap if the film tears.
• Sap bleeding. Pawpaws can bleed heavily, and a soggy, potted rootstock will push sap that floats the scion loose. Let a potted tree dry down before grafting and work in dry weather.
• Transplant shock. Grafting and transplanting at the same time stacks two stresses. Graft in place, or let a tree settle before you graft it.
• Impatience. Some unions stay green but barely grow for a season before taking off. A stalled graft is not always a dead one, give it a year. If it truly fails, cut the rootstock back and re-graft the following spring.

Keep going

• How to grow a pawpaw from seed (raise your own rootstock)
• Named pawpaw varieties to graft, and when they ripen
• The pawpaw tree: how big, how fast, how to grow one
• Can I grow a pawpaw where I live?