Most apples cross-pollinate each other just fine as long as bloom times overlap. But some varieties make sterile pollen that won't work on any tree at all. Look up apple cross-pollination compatibility lists before you buy your trees. Bad pairings can ruin your harvest plans.
I made this mistake with my first orchard when I planted a Jonagold next to a Fuji. My Fuji bloomed great but made almost no fruit for two years. Jonagold is a triploid apple. Its pollen can't do the job for any other variety at all.
Triploid apple pollination fails because these trees have three gene sets instead of two. This extra set throws off their pollen so it can't finish the job. The pollen looks fine and bees carry it like normal. But it won't grow a tube to reach the seeds.
WSU lists the main incompatible apple varieties you should know about before you buy. Baldwin, Gravenstein, Jonagold, King, Mutsu, and Winesap all make bad pollen. You can grow these for eating but need a third tree to pollinate them and your other apples.
Regular Diploids
- Compatibility: Most common apples like Gala, Fuji, and Honeycrisp cross with each other just fine.
- What works: Any two diploids that bloom at the same time can share pollen both ways with ease.
- Apple cross-pollination compatibility: Check bloom charts to match early, mid, or late season types.
Triploid Varieties
- Problem: Gravenstein, Jonagold, Mutsu, and Winesap make sterile pollen that can't pollinate anything.
- Triploid apple pollination: These need pollen FROM other trees but can't give any back in return.
- Solution: Plant two diploids near each triploid so all your trees get the pollen they need.
Same Family Groups
- Hidden issue: Some apples share genes that block each other even when both make good pollen.
- Incompatible apple varieties: A few pairs like Red Delicious and Empire don't work well together.
- Fix: Choose varieties from different parent lines to avoid these genetic problems in your yard.
My neighbor planted a Gravenstein hoping it would pollinate her Gala tree that year. She got a nice harvest from her Gala but the Gravenstein made almost nothing. Neither tree could help the other at all. She added a Golden Delicious and now all three produce well.
Your bloom timing matters as much as genetics for good fruit set each year. Early blooming trees finish before late types even open their flowers. Bees can't move pollen between flowers that bloom weeks apart even if the varieties match well on paper.
Check both factors before you buy your next apple tree for your yard. Look up the bloom timing to make sure it lines up with your other trees. Then see if either one is a triploid that needs extra partners to make fruit each year.
Crabapples work great for apple cross-pollination compatibility when you have a small yard. They bloom for weeks and make pollen that pairs well with most apple types. One small crabapple can help many trees including your triploids.
Read the full article: Complete Apple Tree Pollination Guide
