We graft onto the hardiest rootstock we can find. It seems the plum rootstock is the most difficult to find from year to year. Most available rootstock are seedling rootstock, and as there may be some degree of open pollination, there will be some variability in the offspring's traits. As a result not all will survive the winters. We find that about 80-90% of the grafted trees survive the first winter, if planted. Survival in pots on the ground is less.

Apple Rootstock

Malus baccata. Seedling rootstock. This is the Siberian Crabapple. Is hardiest apple rootstock known, hardy to USDA Zone 1, and produces a semi-dwarf tree. These trees are smaller that those grafted onto ranetka, and tend to bear fruit a year or so earlier. This rootstock is prone to sending up suckers form the base of the main stem and also from roots. Malus baccata is native to Eastern Siberia, Russian Far East, Mongolia, China, Korea, Bhutan, India, and Nepal, where it is common in mixed forests on hilly slopes at elevations up to 1500 meters. This reportedly accepts varieties better that have a lot of crabapple in their heritage. The winter of 2012-2013, which had a brutal spring I entered with about 100 grafted apples in pots. They all sat on the ground all winter, they were about 50% grafted onto Ranetka and 50% on baccata, almost all the varieties grafted onto baccata survived and none of the Ranetka survived. This sold me on this rootstocks hardiness. I am testing more varieties to evaluate the compatibility issue people talk about.

It seems that trees grow slowly on this rootstock for a year or two and then begin growing rapidly. many 3-4 year trees are 6-8' tall, and the rapid growth may turn into earlier fruiting.

Malus ranetka. Seedling rootstock. It is a cross between Malus baccata and the Dolgo Crabapple. It is not quite as hardy as baccata, only hardy to USDA Zone 2. It accepts a wider variety of apples willingly, produces a larger tree and fruits slightly later than varieties grafted onto bacatta. It does not sucker as much as baccata. Grows to 40’. A vigorous grower with profuse white flowers. Purple elongated fruit.

Malus Dolgo. (Dolgo Crabapple) I have grafted onto this and so far the grafts seem to be doing well. It will produce a standard sized apple tree. This tree grows upright with an open habit around 30' in height with a 20-30' spread. It is very ornamental and provides fair cover for farmstead windbreaks, wildlife and riparian plantings, and highway beautification. It produces pink buds that open to fragrant, white flowers. The bright red to purple fruits ripen in August and are about the size of small plums and are excellent for jelly making and spicy butters which is good eating for humans as well as great browse for birds and wildlife. After 2-3 years in the ground the trees seem to be fine, and I may graft more to this.

Malus Selkirk. (Selkirk Crabapple) This crabapple is often sold as an ornamental because of its pink flowers. In 2019 we got a lot of Malus Selkirk and as of this writing (May 2020) the trees we grafted onto it are mostly growing vigorously and did well over the winter. Malus Selkirk is growing in the coldest areas around Fairbanks so must be hardy to Zone 2a, possibly Zone 1. It will be interesting to see how these trees do in the coming years.

Plum Rootstock

Our plum trees weathered the winter of 2012-2013 much better than the apples, we did not lose any, and none showed any appreciable dieback. We have plums grafted onto these two rootstocks.

Prunus Nigra (Bounty) (Canada or Black Plum) is a seedling rather than a clonal rootstock. very prolific with large fruits up to 1 1/2" in size. P Nigra is a native of North America from New Brinswick to Connecticut. It bears at an early age - 4-6 years from seed. It grows in the most inhospitable sites and fruits where temperatures go below -40 F. Unlike the American plum, this plant does not sucker and makes a small tree or shrub with an open crown. Fruits are produced in abundance along the edges of the braches on spurs. Can tolerate light shade. Height to 15 ft with equal width.

Prunus Americana (American Plum) is also a seedling variety. I have several trees grafted onto this rootstock and all seem to be fine. Appears hardy to -40F, and so far I have not had a problem with suckering. Our trees on this rootstock fruited at 6 years. They show little dieback and appear quite vigorous and will likely outgrow the space I gave them.

Pear Rootstock

Pyrus ussuriensis, or the Ussurian or Harbin Pear. This is the hardiest of the pears, hardy to USDA Zone 2. Growth habit is rounded and dense, reaching 40 to 50 feet in height. The foliage is glossy dark green in summer, and reddish-purple or red in the fall. Flowers are 1 1/3 inches in diameter, pinkish buds opening to white flowers, in late spring. The fruit is round, greenish-yellow pome. It is the least susceptible to fireblight. A very good choice for colder climates, very ornamental. Native to northeastern Asia.