Most trees need less fertiliser than the back of the bag suggests. The trick is timing, balance and matching the feed to the tree.
When to feed
Early spring is the universal window. The tree is waking up, ready to use nutrients. A second light application in mid summer pushes hedging growth or late season flowering. Skip autumn feeding so new growth has time to harden before winter.
Match feed to tree
Magnolias, Crepe Myrtles, deciduous feature trees: balanced slow release in early spring.
Fast hedges like Ficus Hillii: balanced spring feed plus a mid-summer top-up to keep growth running.
Mediterranean trees (Olives, Bay): light spring feed only, ideally compost.
Australian natives (Banksia, Grevillea): low-phosphorus native fertiliser or nothing once established. Standard phosphorus-rich blends are best skipped — these natives are happiest on the native-specific blend.
How much
Less than the label says, almost always. Light frequent feeding outperforms heavy single doses. Water in well to settle the feed into the soil.
Where to apply
Spread fertiliser at the drip line (the edge of the canopy), not at the trunk. That is where the active feeding roots live. Pull mulch back, apply, replace mulch, water deeply.
What not to do
Hold off feeding a tree that's recovering, give it time first. Skip feeding in extreme heat. Skip high-phosphorus blends on natives. Skip heavy nitrogen on flowering trees, it pushes leaf at the expense of flower.
Frequently asked questions
Do I need to fertilise mature trees?
Usually no. Established trees with deep root systems generally find what they need. Feeding helps when trees are growing fast or in poor soils.
What about organic fertilisers?
Compost and well-rotted manure work well for most trees, especially Mediterranean and deciduous. Slow release synthetic fertilisers give more predictable results for hedges.
Can I overfertilise?
Yes. Salt build-up and runoff into waterways are real considerations. More is rarely better.
I have an Agonis After Dark when should I fertiliser it and with which fertiliser would be best, it’s looking a little sad at the moment.
Thank you for any suggestions, Joseph x