Butternut

Size, growth and what to expect

Butternut grows fast as a seedling and at a medium pace after that, the foot and a half a year our growth estimator uses. Most trees reach 40 to 60 feet, with a broad, open crown 40 to 60 feet wide. It is short-lived, seldom passing 75 years.

It flowers from April to June, and the nuts ripen in September and October. They hang singly or in clusters of up to five, each an oblong nut about 1½ to 2¼ inches long in a sticky, hairy husk that does not split. The kernel is sweet and oily, and squirrels, mice and other wildlife eat it.

It grows wild from New Brunswick and southern Quebec west to Minnesota, and south to Arkansas, northern Alabama and Georgia. Its home is rich woods on stream terraces and in valleys, and dry, rocky slopes. The canker now reaches the whole range, and the species has lost 58 percent of its trees since the 1980s. The IUCN lists the species as endangered.

How to grow Butternut

Butternut wants full sun and a deep, rich, well-drained soil, the kind found on stream terraces and at the foot of slopes. It will not survive shade from above. It also grows on dry, rocky slopes over limestone, better than black walnut does. Set trees 40 feet apart, and keep each one 30 feet from a wall and more than 50 feet from overhead wires. Its roots and husks release juglone, though less than black walnut, so keep tomatoes and other sensitive plants outside its drip line.

Saplings ship bare-root or potted. Plant a dormant sapling from leaf fall until bud swell, in a hole deep enough for the taproot to hang straight. Set the root flare at the soil line, put the native soil back in, and keep the mulch clear of the trunk. Plant it young and leave it be, since its roots grow fast and an older tree moves badly. Sow nuts in fall one to two inches deep under hardware cloth, or squirrels dig them up. For spring, hold them damp in the refrigerator for 90 to 120 days first. Seedlings come up in spring.

Water weekly through the first summer when rain is short, and keep a wide mulch ring off the trunk. Deer favor butternut leaves and twigs, and bucks rub young trunks, so cage the tree for its first years. Prune as little as you can, since pruning wounds may let the canker in.

Male and female flowers grow on the same tree but seldom open together, and a lone tree with no other butternut nearby may set few nuts. Plant two or more for a crop. Seedling trees start bearing at about 20 years, with good crops every two or three years. Butternut canker is the grave trouble. Sunken cankers with inky black centers girdle the branches and trunk, and no treatment prevents or cures it. The fungus can travel on the seed, so check young trees closely for cankers. The butternut curculio also damages young stems and nuts.