Avocado still on the tree

Avocado

Already well known as a delicious and healthy fruit, avocados are seeing a surge in popularity lately. People are going wild for guacamole, and avocado toast is being served in trendy restaurants.

But it’s not always easy being green; the laurel wilt disease has the potential to hurt Florida’s avocado industry. The fungal pathogen, spread by tiny beetles, is responsible for killing more than 13,000 commercial avocado trees in South Florida since 2012. But scientists are racing to find solutions to this disease, and as a home gardener the risk may be worth the reward of growing your own guacamole ingredient in the backyard.

There are many varieties of avocado. The varieties best for growing in South Florida are commonly called Florida avocados or green-skin avocados. These are not the dark green ‘Hass’ avocados grown in California; Florida avocados are bright green and have lower fat and calories than their California counterparts.

Characteristics

Avocados (Persea americana Miller) are classified into three groups or “races”: West Indian, Guatemalan, and Mexican. The avocados we grow here in Florida are West Indian types; this group sets fruit early in the season. Guatemalan-West Indian hybrids and Guatemalan types set fruit later in the season. The first table in the UF/IFAS publication "Avocado Growing in the Florida Home Landscape" can provide you with more information on these avocado groups.

Florida's avocado trees grow to be between 30 and 65 feet tall. These trees are classified as evergreens, although some varieties lose their leaves for a short period of time before and during flowering. The tree’s canopy can range in shape from low, dense, and symmetrical, to upright and asymmetrical.

There is variation in the shape and size of avocado fruits. West Indian types are recognizable by their smooth, bright green skin, and the hybrids (Guatemalan x West Indian) have smooth to slightly bumpy skins. Winter Mexican types grown in Florida are quite small and have a dark, wrinkled peel. Because of their lower fat content you may have seen Florida avocados marketed in the store as a “slimcado”. Besides the benefit of having less calories, a lower fat content means that when cut up, Florida avocados hold up a bit better. This makes them a great choice for using sliced or diced in salads or tacos. The taste of these avocados varies, with some varieties very mild (even bland) to many with a nutty flavor. Some people prefer the taste over that of the 'Hass' avocado; UF researcher Edward “Gilly” Evans describes Florida avocados as far more flavorful.

Planting and Care

You can't discuss avocado trees without discussing laurel wilt. This deadly disease kills tree species in the laurel family (Lauraceae), of which avocado is a member. Laurel wilt is caused by a fungus that is introduced to the trees by several species of beetles. This disease is currently threatening the avocado industry in Florida, but that doesn’t mean you shouldn’t consider planting a tree in your backyard. If you're in an area where avocados are not being commercially grown, it's most likely that you can safely grow avocados in your landscape. Be sure to only purchase avocado trees from registered nurseries. For more information, see the latest news from UF/IFAS on avocados.

As a rule, avocado trees do best in areas of Florida that don’t freeze. There are a few moderately cold-tolerant varieties like 'Choquette' or 'Booth 8' that can be grown with good site selection and freeze protection.

When purchasing avocado trees you should know that they are divided into groups. Varieties are classified into A and B types, depending on the time of day flowers are open for pollination. Type A varieties have flowers that are receptive to pollen in the morning and shed their pollen in the afternoon. Type B varieties have flowers that shed pollen in the morning and are receptive to pollen in the afternoon.

Varieties will also differ on whether they set fruit with self-pollination (meaning you need only one tree) or cross pollination (meaning you would need two different tree types). Varieties that set fruit well when planted alone are ‘Waldin’, ‘Lula’, and ‘Taylor’. On the other hand, the varieties ‘Pollock’ and ‘Booth 8’ need a type A tree planted in the same area. The intricacies of avocado varieties can become a bit complex—if you want to dig a little deeper, you can check out "Avocado Growing in the Florida Home Landscape."

It can be a fun experiment to try and sprout a seed from an avocado in your kitchen, but this project isn’t likely to provide you with a tree that grows tasty fruit. Trees grown from seed may take four to ten years to flower and fruit. For desirable fruit, grafted avocado trees from registered nurseries are best. (If you want to learn more about grafting, an excellent resource is the book Propagating Fruit Plants in Florida, available from the UF/IFAS bookstore.)

When looking for a tree, try to find one that is about 2 to 4 feet tall in a 3 gallon container. Don’t worry if your tree seems small; they grow fast. Grafted avocado trees will begin to produce fruit after three to four years. Trees should be planted at least 23 to 30 feet away from buildings and electrical wires, as well as other trees to ensure that they receive enough sunlight.

When choosing a planting location for your tree, there are a few things to keep in mind. Avocado trees can get quite big if unpruned; to keep a tree under 15 feet, a few judicious pruning cuts each year are necessary. Limbs can be broken by strong winds or heavy crop loads. And finally, these trees don’t tolerate flooding or poorly drained soils.

Did you know that avocado fruits don't actually ripen on the tree? Avocados ripen between three and eight days after being picked. Still, it can be difficult to determine just when to pick green avocados from the tree. Generally speaking, if you see fruit dropping you can assume the tree is ready to be picked. You don't need to harvest all fruits at the same time; you can pick them as you need them. Be aware though, as the season progresses, the fruit will eventually drop off the tree. Florida avocados will ripen best when it's over 60 to 75 degrees Fahrenheit outside. "Avocado Growing in the Florida Home Landscape" includes a table showing the general time period various avocado varieties can be harvested.

With avocados being so in vogue at the moment, why not try growing them if you have the space?

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