What if your apple tree blooms every 2 years: prevent biennial bearing

TL;DR

Biennial bearing (alternating heavy and light fruit years) happens because a heavy crop year exhausts all the tree's energy. The next year, the tree recovers and grows instead of making flowers. Root cause: preventing overload and conserving energy. Solution: thin young fruit during heavy years, consistent feeding and water, and adjust pruning to restore balance.

Why does your apple tree fruit in cycles (heavy, light, heavy, light)?

This pattern is called "biennial bearing" or alternate bearing. It is the tree's natural response to exhaustion. In a "heavy year," your tree carries enormous fruit load. The tree pours all energy into those fruits: blossoms, seed formation, stops branch growth. By autumn, the tree is depleted.

The next year, that same tree produces almost no flowers. Instead, it grows taller, makes more leaves, and restores itself. Only two years later do many flowers return.

This is not your tree's preference - it is self-protection. A tree that exhausted fully every year would die within decades. This pattern loads heavily every other year and recovers.

Why does this happen more in some cultivars?

Not all apple cultivars show strong biennial bearing. Some varieties are "poor bearers" and need stronger rest periods:

Very prone to biennial bearing:

• Jonagold: extremely susceptible
• Gravensteiner: moderately susceptible
• Boskoop: moderately susceptible

Less prone:

• Elstar: fairly consistent
• Gala: fairly consistent
• Golden Delicious: moderately susceptible

The pattern is worse in years with abundant blossom (good pollination) and less feeding.

Thinning: the first step

The key to breaking biennial bearing is thinning young fruit during the "heavy years." This sounds backwards: you have abundant fruit, so why remove it? But this small intervention stops the exhaustion cycle.

How thinning works:

After bloom (May-June) you see tiny apples on branches. This is the moment. Thin out all small fruit until roughly 1 apple remains per 15 cm of branch. So on a 60 cm branch, keep 3-4 apples.

Removing this young fruit goes against instinct, but the effect is powerful:

• The tree invests less energy in fruit development
• More energy goes to growth and foliage
• Next year it forms flowers normally again
• The apples that remain grow larger and more beautiful

Practice: Start late May when apples are thumbnail-sized. Use thinning shears or gently snap them off. Do not collect them - they are gone.

Feeding and water: consistency is key

An underfed tree more easily enters biennial bearing. Energy is scarce, so the tree budgets strictly. Consistent feeding prevents this.

March feeding: In March add compost or balanced fertiliser (NPK 7-7-7). This gives energy for the growing season.

Water: Apple trees want consistently moist soil, not wet. In dry periods (more than two weeks without rain), water. An thirsty tree grows poorly and more easily becomes alternate.

Summer mulch: In May lay a layer of wood chips around the tree. This keeps the soil moister and cooler in summer. Less water stress = less biennial bearing.

Pruning: restore balance

Pruning also helps. Not hard pruning, but deliberate maintenance.

In a "heavy year" (much fruit) you can carefully remove some growth. This sounds odd (remove growth?), but it signals the tree not to exhaust fully. Remove small twigs that overlap each other. Not more than 10-15% of the canopy.

In a "light year" (few fruit), prune more gently. Let the tree do its growth. Remove only dead or broken branches.

After three to five years of deliberate thinning and feeding you will notice the pattern flattens. The tree learns from consistent conditions and moves toward normal fruiting.

Step-by-step

Step 1: Recognise the pattern

Note for three years: heavy fruit or light fruit? Do you see a clear alternating rhythm? Yes = biennial bearing. That is normal.

Step 2: Thin in the heavy years

Late May/early June, when apples are thumbnail-sized, thin out all fruit to 1 per 15 cm of branch. This is the most impactful step.

Step 3: Stabilise water and feeding

Feed in March and mulch in May. Water regularly in dry periods. This weakens the tree's "exhaustion trigger."

Step 4: Adjust pruning

In heavy years, light maintenance pruning only (10% maximum). In light years, let the tree grow and remove only dead wood.

Step 5: Patience and consistent repetition

This takes three to five years before the pattern disappears. Keep thinning and feeding. The tree learns slowly.

Frequently asked questions

Is biennial bearing bad for the tree?

No. It is the tree's natural self-protection. However, it is bad for you as a garden designer: you have inconsistent fruit, many years without harvest. So we want to break it for stability.

Can I use chemicals to stop biennial bearing?

Gibberelline products can suppress it, but they are not easy for home gardeners. Thinning is the manual, reliable way. Better than chemicals.

How much fruit must I remove when thinning?

Average 80-90% of young fruit. Yes, it feels brutal. But this is essential. Ultimately what remains grows much larger and more beautiful, so you lose nothing in total harvest.

What if I forget to thin in a heavy year?

You will likely get another light year. Once biennial bearing sets in, breaking it without thinning is hard. So remember: thinning is not optional, it is the core intervention.

When do I see results?

Year 1-2: still alternating, but heavy years become less extreme. Year 3-5: pattern flattens, more consistency. Very patient, but it works.

Frequently asked questions

Can my tree be "old" and therefore biennial?

No, young and old fruit show the same pattern. Old trees do tire faster, however. If your tree is older than 25-30 years, biennial bearing may take more effort to solve.

Which cultivars have this least?

Young, flexible varieties like Elstar and Gala have the least trouble. Heavy bearers like Boskoop have the most. Thinning helps all equally.

Can I use synthetic fertiliser instead of compost?

Yes, but less ideal. Compost gives stability; fertiliser gives quick spikes. Consistency beats strength.

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