Apple varieties differ less in flavor than in three things that decide whether a tree ever fruits at all: bloom timing, pollen compatibility, and mature size. Clemson Cooperative Extension (HGIC 1350) sorts common varieties into bloom groups A, B and C, and USU Extension ties a tree’s eventual height to its rootstock, from 8-12 feet on M.9 up to 35-40 feet on seedling stock. Before ordering anything, check the rootstock code on the tag and cross it against the bloom groups of whatever else is already planted nearby.
Why it matters
Choosing a variety is a decision made once, at the nursery order or the rootstock label, and it locks in for the life of the tree how tall it grows, when it flowers, and whether it can pollinate the tree next to it. Get any of these wrong and the mistake doesn’t surface for years, when a tree covered in blossom sets little or no fruit. This decision sits upstream of the planting steps covered in Growing Apples, and it’s worth settling before a single hole gets dug.
Two separate jobs, one nursery tag
Rootstock and variety are grafted together but answer different questions. Rootstock, not variety, fixes how tall the tree eventually stands: USU Extension lists M.9 at 8-12 feet, M.26 and G.11 at 12-15 feet, G.30 and M.7 at 18-20 feet, M.106 at 25-30 feet, MM.111 at 30-35 feet, and seedling rootstock at 35-40 feet. A ‘Honeycrisp’ on M.9 and the same ‘Honeycrisp’ on seedling rootstock end up as two very different trees in the same yard, one you can prune from a stepladder and one you can’t.
Variety decides something rootstock never touches: bloom timing and pollen compatibility. This matters most in a small home orchard, where there’s room for two or three trees and no margin for a pairing that never overlaps in bloom. Working out Which Varieties Actually cross-pollinate each other is a separate question from size, and it’s covered in detail at Apple Pollination: Which Varieties Work Together.
When to do it
The decision has to be made while the tree is still dormant, because that’s the stage at which bare-root trees and grafted whips ship from nurseries. Order after growers have broken dormancy and pushed leaves, and the rootstock or variety combination you wanted may already be gone for the season.
Bloom order holds, the calendar doesn’t
Bloom group timing is anchored to a stage, not a date. Group A varieties such as Anna and Dorsett Golden open first, group B follows, and group C finishes the sequence, according to Clemson HGIC 1350:
- Group A: Anna, Dorsett Golden
- Group B: Fuji, Gala, Ginger Gold, Granny Smith, Jerseymac, Mollie’s Delicious, Mutsu, Red Delicious, Yates
- Group C: Arkansas Black, Golden Delicious, Jonagold, Ozark Gold, Priscilla, Rome Beauty, Stayman
What moves the actual calendar date of bloom is local climate and chill accumulation. A group A and group B pair that overlaps enough to pollinate each other in one region may drift further apart somewhere else. The order of the groups holds everywhere. The number of days between them does not.
This is also the stage to settle pollen compatibility, since it can’t be fixed after planting without adding a tree or grafting a new limb onto an existing one. If the yard only has room for a single tree, this is the point to decide whether to graft a second variety onto it later instead of planting a second tree now, a question worked through at Grafting an Apple Tree: Adding a Variety to What You Have.
How to do it
Work through the choice in a fixed order: rootstock first, because it commits the yard to a size, then variety, because it sets bloom timing and fruit type, then pollinizer, because some varieties can’t do that job for anyone.
Size the tree to the space first
Rootstock is usually a code on the nursery tag, printed below or beside the variety name, something like M.9 or MM.111. Match it to the mature height the site can actually take:
| Rootstock | Mature height (USU Extension) |
|---|---|
| M.9 | 8-12 feet |
| M.26 | 12-15 feet |
| G.11 | 12-15 feet |
| G.30 | 18-20 feet |
| M.7 | 18-20 feet |
| M.106 | 25-30 feet |
| MM.111 | 30-35 feet |
| Seedling | 35-40 feet |
A tree destined for 35-40 feet on seedling rootstock has no business going in against a fence line eight feet from the property line. A dwarfing rootstock like M.9 solves that but needs staking for its whole life, since the root system stays small too.
Then line up bloom groups
Once rootstock is settled, pick varieties whose bloom groups sit at the same letter or one apart. Two group B trees, or a group B next to a group A or C, generally overlap enough to set fruit. Two trees at opposite ends of the sequence, group A next to group C, are the riskiest pairing in a two-tree yard.
Rule out an all-sterile pairing
Last, check the pollen. Jonagold, Mutsu, Stayman and Winesap all carry sterile pollen, according to Clemson HGIC 1350, UGA Circular 740, and USU Extension. Each needs a different variety nearby to set fruit and cannot serve as that pollinizer in return. A yard holding only two of these four produces plenty of blossom and no crop. Pair any one of them with a fertile variety from a compatible bloom group instead.
What goes wrong
The most common failure is a garden planted entirely with sterile-pollen varieties. Two Jonagold trees, or a Jonagold next to a Stayman, bloom heavily and set almost nothing, because neither tree can supply usable pollen to the other. This doesn’t show up as a problem until the third or fourth year, when the trees are old enough to flower and the grower is left wondering why a yard full of blossom yields a handful of apples.
Bloom groups too far apart
A second failure is pairing bloom groups that don’t overlap enough in a given climate. Group A finishes flowering before group C has properly opened in some regions, which leaves no window for cross-pollination even though both trees are perfectly fertile on their own. The fix isn’t a different variety necessarily, it’s checking local bloom overlap rather than assuming the letters alone guarantee a match everywhere.
Rootstock sized for the catalog photo, not the yard
The third failure is planting seedling or MM.111 rootstock, which USU Extension puts at 30-40 feet at maturity, in a space sized for a dwarf tree. The mistake is invisible for the first several years while the tree is small, then becomes expensive to fix once it’s shading a vegetable bed or pressing against a roofline, at a size where moving or removing it is a serious job rather than a quick one.
What changes where you are
Bloom order stays fixed everywhere: group A varieties open before group B, and group B before group C, per Clemson HGIC 1350. What changes by region is how many days separate the groups, and how much that gap widens or narrows depending on local chill accumulation and how a given spring warms up. A pairing that overlaps comfortably in one climate can end up with a much tighter or wider bloom window somewhere else.
Check chill hours and frost dates locally
Chill hour requirements and expected last-frost dates are specific to a state and even a county, and none of the figures in this piece are meant to stand in for that. Check those numbers with a state or county extension office before finalizing a variety list, since a variety that blooms reliably in one region can bloom too early or too late for the local frost pattern in another. The rootstock and bloom-group facts here come from USU Extension, Clemson HGIC 1350, and UGA Circular 740, and hold nationally, but the calendar dates layered on top of them do not.
Common questions
Can I plant just one apple tree and still get fruit?
Only if that single variety is genuinely self-fertile, and even those tend to set a heavier crop with a second variety nearby for cross-pollination. If space only allows one tree, grafting a second variety onto it later, as covered in the grafting guide linked above, solves the pollinizer problem without a second trunk.
Do crabapples count for pollination?
A flowering crabapple with an overlapping bloom period can supply pollen to a nearby apple variety, since bloom group is about timing rather than fruit size. Check that its bloom window actually overlaps with the variety you’re trying to pollinate before relying on it.
Why did my two apple trees bloom at completely different times?
They’re probably in bloom groups further apart than they look on paper, or one is a variety with a naturally wide bloom window. Check both against the Clemson HGIC 1350 bloom group listing rather than assuming similar-sounding varieties bloom together.
Does rootstock affect fruit flavor or size?
No, rootstock controls tree size and some disease resistance, not fruit taste, which comes from the grafted variety itself. Two trees of the same variety on different rootstocks should produce apples that taste the same, just on trees of very different heights.