Every apple needs pollen from a different variety that blooms at the same time, and that goes for all 137 apples and crabapples on our map. Plant two varieties in the same bloom group, or one group apart, within about 100 feet: Zestar and Haralson (both group 4) work together, and either one works with Honeycrisp (group 5). Triploids like Gravenstein need two partners, and a crabapple is one of the easiest partners there is.
Every apple needs a partner
Bob Purvis puts it plainly in his lecture notes: apple pollination takes two different cultivars that aren't related to each other. A pollenizer supplies the pollen. The bees are the pollinators. So Dolgo pollenizes Norland, and bees pollinate the blossoms.
A different variety means different genetics. Every tree of a named variety is a clone of the same original tree, so it counts as one plant, and two Haralsons are still one Haralson. Sports count as the same tree too. RubyMac, Red McIntosh and Fred's Mac are all McIntosh sports, so they can't pollenize each other. Pollen only works within one kind of fruit, so a pear won't help.
Purvis's tell for failed pollination: after petal fall, the young apples that took stay bright green, and the rest turn yellow, wither and drop.
How bloom groups work
Two apples overlap enough to pollenize each other when they sit in the same bloom group or one group apart. We give every variety a group from 1 (very early) to 7 (very late). Groups only compare varieties of the same fruit, so an apple in group 4 and a plum in group 4 don't bloom together. In most springs apples and crabapples bloom last, after apricots, plums, peaches, pears and cherries.
For apples, the groups start from measured bloom dates at the Apple Biodiversity Collection in Nova Scotia, checked against multi-year nursery and extension groupings. Where there was no record, the group is our best estimate from the variety's origin and relatives, and the map marks it. A warm or cold spring moves every tree earlier or later, but the order stays about the same.
Our apples by bloom group
Of the 137 apples and crabs on our map, 120 bloom in groups 3 to 5, and none of them lands in group 1. Examples from each group, with triploids and disputed pollen listed separately:
| Bloom group | Examples with good pollen | Triploids and disputed pollen |
|---|---|---|
| 1, very early | None of the apples or crabs we carry | None |
| 2, early | Dolgo Crabapple, Chestnut Applecrab, Norland | None |
| 3, early-mid | Wickson Crabapple, Hewe's Virginia Crabapple, Liberty | Triploids: Belle de Boskoop, Gravenstein, Red Gravenstein |
| 4, mid | Zestar, Haralson, Frostbite | Triploids: Claygate Pearmain, Ribston Pippin. Disputed: Newtown Pippin |
| 5, mid-late | Honeycrisp, Wealthy, Northern Spy | Triploids: Ashmead's Kernel, Baldwin, Karmijn de Sonnaville, Roxbury Russet, Stayman Winesap. Disputed: Arkansas Black |
| 6, late | Brown Snout | Disputed: Mother |
| 7, very late | Binet Rouge, Ellis Bitter | None |
Triploids need two partners
A triploid needs two good pollenizers, not one. It carries an extra set of chromosomes, and while it sets fruit fine with a partner, its pollen is poor, so it can't return the favor. Purvis lists Jonagold, Mutsu, Shizuka and Gravenstein as triploids with sterile pollen, and our map flags every triploid we carry.
Those two have to bloom with the triploid and with each other, because a lone partner would have nothing to pollenize it back. So a triploid planting is three trees. For a Baldwin (group 5), Honeycrisp and Haralson do the job. For a Gravenstein (group 3), try Hewe's Virginia Crabapple and Carroll.
A few varieties are in dispute. Some sources call Arkansas Black, Newtown Pippin and Mother triploids and some don't, so we don't count on any of them as the only pollenizer for another tree until that's settled.
Why crabapples make great pollenizers
A crabapple is an apple as far as pollination goes, and the good ones bloom heavy and carry plenty of pollen. Purvis says crabapples make excellent pollenizers if they bloom at the same time as your apples. Washington State University's tree fruit program notes that flowering crabs have become popular pollen donors because they generally bloom longer than apples and are easy to care for, and Penn State Extension says white, single-flowered crabs are best.
Match a crab like any other partner:
- Group 2: Dolgo and Chestnut, for early prairie apples like Norland and Lodi.
- Group 3: Wickson, Hewe's Virginia and Hyslop, for anything in groups 2 to 4.
- Group 4: Otterson and Trail, for the big middle and up through Honeycrisp.
Red Splendor (group 3) is the one we suggest for Zestar, but it tends to bloom every other year, so pair it with a pollenizer that blooms every year. See our crabapple page for more.
Cold springs, bees and pollen tubes
In a cold spring, pollination comes down to temperature, because bees have to fly and pollen tubes have to grow. Purvis explains it: a bee drops pollen on a flower's pistil, the grain grows a tube down the style to the ovule, and that tube grows best at 65 to 75F. Penn State Extension adds that pollen may not germinate below 41F, tubes grow very slowly below 51F, and a flower usually has to be pollinated within 2 to 4 days of opening.
Honeybees work best above 65F, per Purvis, while Penn State says bumblebees and solitary bees fly in weather 5 to 10F cooler.
Luckily, an apple doesn't need every flower. Utah State University Extension puts a full apple crop at 10 to 15 percent of the blossoms. A hard frost at bloom is another matter. In 2026 a grower friend in Gallatin Gateway saw 15F during bloom and got no fruit at all, and no pollenizer fixes that.
Mason bees and other cold-weather pollinators
Blue orchard bees, our native mason bees, are the pollinators to encourage in cold country. Purvis notes they work in much colder weather than honeybees and move from blossom to blossom much faster. J. Bosch and W.P. Kemp's SARE guide says they forage under overcast skies down to 54F and that about 250 nesting females will pollinate an acre of apples, the same job as 1 to 2.5 honeybee hives. They stay within about 300 feet of the nest. Give them:
- Nest holes 19/64 inch across and 6 inches deep (Bosch and Kemp).
- A source of mud nearby.
- Nests set out a few days before apple bloom, facing morning sun (WSU Extension).
- Cocoons stored at 35 to 40F over winter (WSU Extension).
Don't stop at one kind of bee. Penn State Extension says wild bees need flowers before and after apple bloom (willows, bee balm, wild hyssop, milkweeds) and bare, sunny, well-drained ground to nest in. Purvis adds that bumblebees, flies and wasps do some of the pollinating too.
Why our bloom groups differ from other charts
A lot of bloom charts come from places with mild winters, like California, Missouri and the Southeast, and they don't always hold up in cold country. There, a variety that needs lots of winter chill blooms late partly because it's still waiting on chill. Our winters give every tree far more chill than it needs, so bloom order here comes down to how much spring heat each variety needs. We checked the published charts against cold-winter trials and heat-requirement research and moved the varieties that didn't hold up.
Cold winters also bunch bloom together. Purvis noticed that in Minnesota there's relatively little difference in bloom dates compared with coastal climates. It's the same here: most apples bloom within a few days of each other, so most pairings work. The exceptions sit at the ends. Binet Rouge, in group 7, has exactly two partners in our whole catalog: Ellis Bitter and Brown Snout.
Planting for pollination, step by step
Our apple pollination map does most of this for you: pick your tree and it lists every variety we carry that will pollenize it.
- Check that it needs a partner. Every apple and crab does.
- Match the bloom group: same group or one apart.
- Skip the dead ends: triploids, disputed pollen and a tree's own sports.
- Plant within about 100 feet, closer if you can. Bees tend to work the trees nearest each other.
- Add a crab if you have room, and give every triploid two partners.
Seedlings are the exception to the clone rule. Every apple seedling is a new variety, so the trees in a bundle of Wealthy seedlings or Kerr Crab seedlings can pollenize each other once they bloom. We'd still plant a named pollenizer nearby, since a seedling's pollen quality is unknown. If you watch your trees bloom and something doesn't match the map, tell us. The other fruit maps work the same way.
Related guides
- Plan a harvest that lasts three months, not three weeks
- How we rate cold hardiness, and how to read our zone ratings
- Rootstocks for cold country, and why we use ours
Where this comes from
- Our Pollination Maps and Apple Pollination Map pages (bloom groups, triploid flags, partner lists).
- Measured bloom dates from the Apple Biodiversity Collection, Nova Scotia.
- Our product descriptions (Dolgo, Wickson, Hewe's Virginia, Red Splendor, Zestar, our seedlings) and 2026 bloom reports from growers in our network.
- Bob Purvis, Fruit Growing for Homeowners lecture notes.
- Washington State University tree fruit program, on crabapples as pollen donors.
- Penn State Extension: R. Crassweller, Orchard Pollination: Pollinizers, Pollinators, and Weather, and Orchard Pollination: Wild Bees.
- J. Bosch and W.P. Kemp, How to Manage the Blue Orchard Bee as an Orchard Pollinator (SARE, 2001).
- WSU Extension King County, Orchard Mason Bees.
- M. Murray, Critical Temperatures for Frost Damage on Fruit Trees (Utah State University Extension, 2020).
Updated September 2026.