Apple Tree Pollination Chart

Varieties open their flowers in much the same order every spring. Gardeners sort them into flowering groups, from 1 (earliest) to 5 (latest). A tree's best partners are in its own group; the groups either side usually overlap enough. Dates move with the season and the region, so the groups give the order, not a calendar date.

Pick the tree you have or want. The lists show varieties whose pollen should reach it while it is in flower: the same flowering group first, then the groups either side. Triploids are left out as pollen donors because their pollen is sterile. Select any partner to look it up in turn.

Choose two or three varieties growing within about 100 feet of each other. Each tree is checked in turn: which of the others can pollinate it, and how well their flowering groups overlap.

Each fruiting spur opens a cluster of six flowers. The middle one, the king bloom, opens first and usually gives the largest apple. A flower has to receive pollen from another variety within a few days of opening, and the more seeds that form, the better the fruit sizes.

A triploid variety carries three sets of chromosomes instead of two. It sets fruit well with pollen from others, but its own pollen is sterile, so it cannot pollinate anything, not even another triploid. Plant it with two other varieties that bloom with it, so that those two can also pollinate each other.

A crabapple pollinates an apple and an apple pollinates a crabapple. Orchards plant crabapples among the main trees instead of whole rows of a second variety, and a flowering crab in a garden can serve a nearby apple if their bloom overlaps.

Pollen only moves when bees fly. Honey bees work best from about 65°F; bumble bees and other wild bees fly at temperatures 5–10°F lower. Cold also slows the pollen itself, so a cool, wet bloom can leave a poor set even with plenty of hives.

Buds harden off less and less as they open. From tight cluster to petal fall, about 28°F held for 30 minutes kills 10% of the flowers and 24–25°F can kill 90%. Because a full crop needs only a few percent of the flowers to set, a light frost often still leaves enough.

In a garden, two varieties that bloom together within about 100 feet are enough, or three if one is a triploid. In an orchard, the nearer the pollinizer the better, because bees tend to work along a row. Choose a pattern and the size of the block to see how many pollinizer trees it takes.