Olive Tree Fertilizer: What, When and How Much to Feed
Best fertilizer for olive trees in the ground and in pots, when to feed, nitrogen amounts by tree age, potassium and boron, and signs of deficiency.
Olive trees are not heavy feeders, but a well-fed tree grows more fruiting wood and crops more regularly. The most important nutrient is nitrogen, followed by potassium and the micronutrient boron. Feed in late winter or early spring, with an optional second feed after flowering, and stop by midsummer.
Best Fertilizer for Olive Trees
- Garden trees: well-rotted manure or compost spread under the canopy in late winter, plus a balanced granular feed if growth is weak.
- Potted trees: a balanced or citrus/Mediterranean liquid feed every 2–4 weeks from spring to late summer, or a slow-release granule each spring.
- Groves: a nitrogen-rich fertiliser split into two or three applications, guided by leaf analysis.
When to Fertilize
- Late winter to early spring: the main feed, before the new flush and flowering.
- After fruit set (late spring to early summer): a lighter second feed on cropping trees.
- Never in autumn: late nitrogen produces soft growth that frost damages.
In the Southern Hemisphere the same timings fall roughly six months later (main feed in August to September).
How Much Nitrogen?
| Tree | Nitrogen (N) per tree per year |
|---|---|
| 1–2 years old | about 30–60 g (1–2 oz) |
| 3–5 years old | about 100–250 g (4–9 oz) |
| Mature, cropping tree | about 0.5–1 kg (1–2 lb) |
These are amounts of nitrogen, not of fertiliser: a 20% N product contains 200 g N per kilogram. Spread fertiliser over the root zone from about half a metre from the trunk out to beyond the drip line and water it in.
Potassium, Phosphorus and Boron
- Potassium: heavy crops remove a lot; shortage shows as scorched leaf tips and is common on dry, sandy soils.
- Phosphorus: rarely limiting in established trees.
- Boron: important for flowering and fruit set; deficiency causes misshapen fruit and dieback. A small foliar boron spray before flowering helps on deficient soils. Do not overdo it; boron is toxic in excess.
- Calcium and magnesium: usually adequate on alkaline soils.
Signs Your Olive Tree Needs Feeding
- Pale, yellow-green older leaves and short shoots: nitrogen.
- Brown, burnt leaf tips: potassium (or salt and drought stress).
- Deformed fruit, poor fruit set: boron.
- Yellow leaves with green veins on young growth: iron, typical in very alkaline or waterlogged soil.
Common Mistakes
- Feeding in autumn.
- Piling fertiliser against the trunk.
- Applying fertiliser to dry soil without watering.
- Feeding a waterlogged tree: the problem is the roots, not the nutrients.
More Olive Tree Guides
- How to Grow Olive Trees: The Complete Guide
- How often to water olive trees
- How to prune olive trees
- Olive tree pests
Frequently Asked Questions
What is the best fertilizer for olive trees?
Compost or manure plus a balanced, nitrogen-rich feed in spring for garden trees; a citrus or Mediterranean liquid feed for potted trees.
When should I fertilize my olive tree?
Late winter or early spring, with an optional light feed after flowering. Never in autumn.
Are coffee grounds good for olive trees?
In small amounts mixed into compost they are fine, but olives prefer neutral to alkaline soil, so do not rely on them as fertiliser.
Is Epsom salt good for olive trees?
Only if a magnesium deficiency has been confirmed; most soils do not need it.
TarlaTapan guides focus on practical, field-tested growing advice. Corrections and suggestions are welcome at info@tarlatapan.tr.