Avocados (Persea americana) are actually a fruit that is used as a vegetable in a variety of dishes. Avocado trees are generally of three types: the Mexican, the Guatemalan or the West Indian. Within these types are many varieties of avocado, including the Hass, Choquette, Miguel and Simmonds. Simmonds avocados grow well in home gardens and produce abundant fruit. Seedlings of Simmonds avocados are generally grafted to other types of rootstock for the best crop production.
Gardeners can grow avocado from the large, round seeds within the fruit. In fact, many people do grow seedling plants from grocery store avocados, but the resulting tree may not be of the same type as the parent tree and may not produce fruit at all. That is because avocado trees are generally grafted onto rootstock. This process combines that reliable production of the rootstock plant with the vigorous new growth of the upper area plant, called the scion. This mixture enhances the best qualities of both plants. When a seed is produced, it will be one or the other of the two, but not a combination of the two plants' characteristics.
To germinate seedlings, place them in a shallow tray or pan with a well-draining, commercial potting mix. Plant the seeds two to three times deeper than their length. You can also germinate avocado seeds by suspending them in water by toothpicks stuck into the seed horizontally and resting on the edge of the container. Germination will occur in 12 to 15 days. You can then replant the seedling into a larger container with a good quality potting mixture.
Grafting Methods for Avocado
Whip grafting is generally used for plants with a 1/4 to 1/2 inch diameter. Grafting is usually done in the spring or fall. The scion, or upper part of the plant, should be from hard and mature green wood. Make a long, sloping cut on the rootstock plant about 1 to 2 1/2 inches long. Make a matching cut on the scion stock. Then, cut a “tongue” on both scion and rootstock plants by cutting down into the slanted wood surfaces. Fit the two cut surfaces on both plants together and apply grafting wax to seal the union.
Grafted Plant Care
Protect the new cuts from sunburn with tape until the graft heals completely. Keep the soil moist but not wet for newly grafted plants. Avocado trees do not like to sit in water, so ensure that the soil drains well by adding amendments such as compost or vermiculite. Fertilize new trees three times a year. Reduce fertilizer when the tree blooms. Nitrogen fertilizers increase resistance to cold temperatures, fruit size and crop yield. Addition of zinc chelate or sulfate micronutrients are sometimes necessary for crops in California.
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