Gadenin日本語Get the appQuince rootstocks are what keep a pear small
A pear on its own roots is a forest tree. Left alone it will run to thirty or forty feet, hold its first fruit at fifteen years and put every crop out of reach. Almost every garden pear is therefore grafted onto quince, a different species entirely, chosen because it is naturally small and because it brings a tree into cropping years earlier. The variety on top gives you the fruit; the quince underneath gives you the height, the rooting depth and the age of first crop.
Quince roots are shallower and less anchoring than pear roots. That is the price of the smaller tree: a pear on quince wants a stake for the first four or five years, and on a windy site for longer. It is also less drought-tolerant, because the root plate sits in the top eighteen inches (45 cm) of soil where the ground dries first.
If your tree is already in and you do not know what it stands on, judge by its growth. Extension shoots longer than three feet in a season on a tree that has been in the ground five years means a vigorous root, and that tree needs wider spacing, summer pruning and a plan for reaching the top of it.
| Rootstock class | Mature height | Spacing | Support | First real crop |
|---|---|---|---|---|
| Dwarfing quince | 8-10 ft (2.4-3 m) | 10 ft (3 m) | Stake for 5 years or longer | 3-4 years |
| Semi-vigorous quince | 12-15 ft (3.6-4.5 m) | 14-16 ft (4.2-4.9 m) | Stake for 4 years | 4-5 years |
| Pear seedling | 25-40 ft (7.6-12 m) | 25-30 ft (7.6-9 m) | Stake while establishing only | 7-10 years |
| Trained on a wall | 7-8 ft (2.1-2.4 m) of wall | 12-15 ft (3.6-4.5 m) of wall per tree | Permanent wires | 3-4 years |
Some varieties are graft-incompatible with quince and are sold with a compatible interstem, a short length of a third variety between rootstock and top. Such a tree has two visible graft unions on the trunk. Both must stay above soil level.
Pears want more heat and more shelter than apples
Pears flower one to two weeks earlier than apples, which puts the blossom straight into the last of the spring frosts. That single fact should decide where the tree goes. Avoid the bottom of a slope, the inside of a solid fence and any hollow where cold air collects on a still night. Halfway up a slope, where cold air keeps sliding past, is the safest ground you have.
Give the tree full sun, eight hours if you can. Pears ripen their wood and set fruit buds on summer heat, and a tree in half shade makes long soft shoots and few flowers. A south- or west-facing wall is the classic position in a cool climate: the stored heat lifts the blossom period above the frost line and finishes the fruit properly.
Soil should be deep, moisture-retentive and free-draining, with a pH between 6.0 and 6.8. Pears tolerate a heavier, damper soil than apples will, but not standing water. Dig a hole a spade deep, fill it with water and come back twelve hours later; if it is still full, plant on a raised mound eight to twelve inches (20-30 cm) high rather than into the sump you have just found.
Getting the tree in the ground
Bare-root trees go in during dormancy, from leaf fall until the buds begin to move, on any day the ground is neither frozen nor waterlogged. Container trees can go in whenever the ground is workable, but they still establish fastest planted dormant. Get bare roots into soil the day they arrive; if that is impossible, heel them into damp ground rather than leaving them bagged.
- Dig wide and shallow Make the hole two to three times as wide as the root spread but never deeper than the roots are long. Rough up the sides with a fork so roots can push out into the surrounding soil instead of circling in a smooth-walled pit.
- Backfill with what you dug out Do not fill the hole with compost or fertilizer. A rich pocket in poor ground keeps the roots inside it and makes a tree that never anchors. Put the compost on the surface as a mulch instead, where worms will take it down.
- Keep every graft union clear of the soil Find the swollen kink low on the trunk and set the tree so it sits four to six inches (10-15 cm) above the finished soil level. If soil or mulch covers it, the variety roots over the quince, the dwarfing is canceled, and in ten years you have a thirty-foot tree.
- Drive the stake before the tree goes in A short stake angled at 45 degrees into the prevailing wind, or a vertical stake set clear of the root ball, both work. Driving a stake after planting spears the roots. Tie loosely and check the tie twice a year for strangling.
- Water in heavily, then mulch Give four to five gallons (15-20 L) slowly, even in wet weather, to settle soil around the roots. Then mulch two to three inches (5-8 cm) deep over the root zone, keeping a clear collar of four inches (10 cm) around the trunk.
The first two summers decide the tree
A newly planted pear has no root reach and cannot fetch its own water. Through the first two growing seasons, water deeply once a week in dry spells, five gallons (20 L) at a time, rather than sprinkling daily. Shallow watering trains roots to stay at the surface, which is exactly wrong on quince.
Keep a three-foot (90 cm) circle around the trunk clear of grass and weeds for those two years. Grass competing at the base costs a young tree more growth than any feed will give back. Do not put nitrogen fertilizer on at planting; feeding a tree that has not yet made roots produces soft shoots that frost and fireblight both take.
Rub out any flower buds that appear in the first spring after planting. It feels wasteful, but a crop carried on an unestablished tree stops root growth for the season and delays the point at which the tree can support real fruit. From the second or third spring, let it crop.
Write down the rootstock, the variety, the pollination group and the planting position the day the tree goes in. In four years, when you are deciding spacing for a second tree or working out why one is not setting, that note is the only record that exists.