Cold tolerant avocados grow well in Melbourne, provided they have a warm sunny position with well-drained soil, a good layer of mulch over the soil and protection from frosts when they’re young. Once you’ve planted up your avocado, you have to feed it regularly to get it growing and eventually fruiting productively (within two to three years of planting for grafted varieties).
The best way to apply fertiliser is to sprinkle it by hand evenly underneath the tree’s drip-zone and a bit further out, as this where the trees feeder roots are. Don’t dig in the fertiliser or cultivate the soil around the roots as avocados have a shallow fibrous feeding root system close to the surface, with almost all feeder roots in the top 15-20cm of soil.
If you use mulch around the tree, which is highly recommended in the warmer seasons, apply the fertiliser under the mulch for best results. Just push the mulch aside, apply the fertiliser and then move the mulch back in place. After applying fertiliser, always remember to water it in.
Avocados have special feeding requirements, as young trees require small amounts of fertilisers regularly to grow well.
Year 1-2: Apply a fertiliser high in nitrogen such as chicken manure or blood & bone every 8 weeks or 2-3 times during the growing season from November to March to promote vegetative growth (leaves and branches).
Apply a very small amount of fertiliser to begin with, then use more fertiliser on the second application. If adding a third application of fertiliser around March, add a small amount only. A third light application of fertiliser in March is highly recommended as all fruit trees need a feed in the beginning of the autumn season.
Year 3 onwards: Fertilise as before but use a more balanced fertiliser instead that will supply the trees nitrogen, phosphorus and potassium needs.
You can continue to use chicken manure or blood & bone which supply nitrogen and phosphorus as long as you add potash (or supplement with seaweed extract which contains high potash levels).
Use approximately 3L of chicken manure and 20g of potash per tree per year. Don’t apply it all at once, use a portion each time you feed the tree as per previous instructions.
Other balanced fertilisers that are suitable for avocados include citrus fertiliser or a general purpose organic fertiliser.
Feeding your avocado regularly will allow the tree to achieve optimum growth and fruit productively as early as possible.