Fruit Trees

Avocado Fact Sheet

Description and Origin: An Avocado Tree are large upright trees growing to about 9m, depending on the variety, although vigorous seedlings can reach twice this size if the conditions are right.
The Wurtz is the smallest variety reaching only 4-6m, making it suitable for smaller home gardens.
Avocados are native to southern Mexico. There are three groups of avocado, Mexican, Guatemalan and West Indian. Most of our varieties are hybrids between the Mexican and the Guatemalan, these trees are a little more cold hardy that the more tropical West Indian varieties which are seldom seen in Australia.

Dwarf Wurtz Avocado Tree

Grouping and Pollination:
Avocados are split into two groups, A and B, for the purposes of cross pollination. If a variety from each group is planted together they will cross pollinate with each other and each tree will produce more fruit than if grown on its own. The fruits take different lengths of time to mature from flowering therefore the fruiting season will also be extended. If there is only room for one tree the A groups tend be more self fertile and will set better on their own than the B group.

Video: Cross Pollination for Avocado Trees

Video: Can Avocado Trees Fruit all year Round?
The answer to this is no but you can vastly improve the length of time that Avocados come off the tree. We explain it in this video:

Location and Planting: Avocados require a full sun position with protection from strong and salt laden winds. The root system is spreading and competitive and they should not be planting too close to buildings or pathways. They do not like root disturbance so take care when planting to disturb the roots as little as possible, to remove young trees from their growing container, cut down the side of the bag and gently lift them out. Give the tree plenty of room to mature; the minimum spacing should be 6m or more between trees. Avocados are very fussy about drainage and will not accept anything less than perfect drainage. 24 hours in a waterlogged position will kill an avocado tree. Avocados thrive in rich, deep, sandy loam soils with a ph of 6-7. They will not survive in a position with poor drainage. If the planting site has heavy clay soils it will need to be mounded with a large pile of compost so that the tree is planted into the mound above ground level, the mound may need to be 1m tall and wide or more if possible. This is essential for good drainage and the survival of the tree.

Water and Nutrients: Trees grow and produce better fruits if they receive regular moisture. Over irrigation can induce rot which is the main reason that avocados fail. To test to see if irrigation is necessary dig a hole about 20cm deep and test the soil by squeezing it together, if it is moist and holds together do not irrigate, if it crumbles in the hand, it may be watered. Young trees are fairly nutrient hungry and like rich, organic soils. Regular applications of fertilizer with added nitrogen, about 4 times a year will be beneficial. Mature trees need only one application of fertilizer in the spring during fruit set with a reduced nitrogen ratio. Too much nitrogen results in excessive leaf growth at the expense of fruit production. Alkaline soils can result in iron chlorosis which appears as yellowing of the leaves, this can be corrected with applications of chelated iron.

Protection and Pruning: Young trees will need protection from both frost and very hot direct sunlight which can burn the stems and trunk of young plants. A small house constructed of 4 star pickets or tomato stakes wrapped with shade cloth or Hessian will do the trick. On cold frosty nights a hat can be placed over this structure to protect young trees. The Bacon has the greatest cold tolerance of the avocado varieties; this can endure temperatures down to -5 degrees. Once established most varieties can handle -2 degrees with little damage. Young avocados can be tip pruned to encourage a bushy habit. Mostly though, avocados do not need pruning. If the tender green branches are exposed to direct sunlight they can suffer from sunburn and dieback. Whitewash any exposed branches with diluted white paint to prevent this.

Mulching: Mulch avocado tree with a thick layer or organic mulch like Lucerne hay. This not only retains moisture levels in the soil, but it also suppresses weeds, protects the root system from extremes in temperature as well as adding essential nutrients to the soil. Make sure to keep the area around the stem of the plant free from mulch, it should never come into contact with the tree as this can cause the trunk to rot.

Knowing when to harvest the fruits can be tricky, mature fruits will show the following signs; the fruit stem will become more yellow, when the fruit is cut and the seed removed, the seed coat is dry and does not stick to the flesh, it is a dark brown colour, dark skinned varieties will show a change in colour from green to purple. Knowing which variety you are growing will tell you when to pick the fruit. If you are unsure pick only one fruit and leave it for 7-10 day to ripen, once it softens the flesh should be a rich green colour, soft and buttery. If the fruit turns black and wilts it is not ripe and needs to be left longer on the tree. Varieties are harvested as follows: Bacon- March – May, Fuerte- April – June, Hass- July – August, Pinkerton- June -August, Reed- August – December, Secondo- August – December, Sharwill- June – July, Sheppard- February – April, Wurtz- August – October.

1 comment:

  1. I have four Avocado trees grown from seed about 8 feet tall and only one metre from the house. I have a feeling I should remove them all as they are too close - could I trim them down and transfer them to a pot - can you help me please.
    Sonia Schwartz
    105a East Tce, Henley Beach 5022
    mobile 0413600084