An attractive and unusual specimen, the leathery green foliage of the avocado tree is a great way to add interest to a garden or houseplant collection. And, with a little care and patience, many varieties can even be encouraged to bear fruit.
Originating in southern Mexico, the popular pear shaped fruit of the avocado tree (Persea americana) is rich in both vitamins and nutrients. A versatile fruit, it has grown in popularity in recent years. Consequently, the avocado tree, from which the fruit comes, is also growing in popularity.
Almost anyone can grow an avocado tree. Just remember that these are warm season plants that are easily damaged in cold and frosty conditions. In cooler climates you should grow them undercover or as a houseplant. Here their glossy leaves provide color and interest however they are unlikely to bear fruit.
Whether you want to grow a large specimen or a small houseplant, this guide to the avocado tree is designed to take you through everything that you need to know.
An attractive specimen, Persea americana is also pleasingly easy to grow in the right conditions.
Can I Grow an Avocado Tree Indoors?
In ideal conditions many avocado tree specimens can reach up to 80 ft.
Dwarf varieties are often a lot smaller and more suitable. growing indoors or undercover.
Plants grown from stones make ideal houseplants. Typically grown for ornamental interest, they rarely outgrow a home or greenhouse. They are also unlikely to bear fruit.
Different Avocado Tree Varieties to Try
Many people begin their avocado tree growing journey with the stone, or seed, harvested from a fresh fruit. This is a fun and easy way to grow an ornamental variety. You can also purchase seeds or young saplings ready for planting. This enables you to select a variety that is more suited to your growing situation.
Purchasing a stone or young plant enables you to select a variety that is more cold hardy and suited to your growing conditions. Commercially produced young saplings are more likely to bear fruit than specimens grown from seed. You can find specimens in a range of sizes from small, dwarf cultivars, ideal for growing undercover, to medium and large sized varieties.
The 3 main varieties of avocado tree are
- West Indian,
From these 3 varieties all cultivars derive.
In cooler climates growers may want to try Mexican variety cultivars. Some of these cultivars can tolerate frosts and temperatures as low as 15 ℉. West Indian varieties are better suited to warmer areas. These plants struggle in cool or cold temperatures.
Hass avocado tree varieties are one of the most commonly grown cultivars. Members of the Guatemalan variety, they tolerate temperatures as low as 25 ℉ but are far happier in warmer places. Exposure to cooler temperatures can cause leaf and fruit drop.
A popular Hass variety is Lamb Hass. Hardy in USDA Zones 9 to 11 the plant is more heat tolerant than other Hass varieties. The fruit’s thick, pebbly skin blackens as it ripens. It is known for its good flavor.
Hass cultivars are amongst the most commonly grown plants.
Del Rio is a Mexican avocado tree cultivar. Producing small fruit, weighing no more than 4 ounces, they boast a rich flavor and high oil content. If planted outside the plants can tolerate temperatures as low as 15 ℉ and still bear fruit.
Mexicola Grande produces glossy, black fruit which is easy to peel. One of the hardiest cultivars, it can tolerate temperatures in the low 20s.
Some species are hybrids. These are usually Mexican varieties crossed with Guatemalan or West Indian cultivars. Despite being more cold tolerant than other varieties, hybrids prefer warm temperatures and are best grown in USDA Zones 9 and warmer.
Fuerte is a Mexican Guatemalan hybrid. Its pear shaped fruit is green with a pale, dense flesh. The fruit is known for its rich, creamy taste. May is another reliable hybrid with a creamy texture.
Holiday is a semi dwarf weeping avocado tree cultivar. In ideal conditions it can reach about 15 ft and produces large, oval green fruit.
Wurtz is considered to be the only true dwarf cultivar. Also known as Little Cado it rarely exceeds 10 ft. A self fertile variety with the right care it can bear fruit from May until September.
Take the time to select a variety that is suitable for your growing conditions and needs.
Take the time to select a specimen that suits your growing position.
How to Plant an Avocado Stone
While young saplings are available, many people enjoy trying to grow their own plant from seed. Or in this case stone. If you are planting a stone freshly harvested from a fruit, remove any flesh before planting.
Germination only occurs if you can provide the right mix of heat, humidity and moisture. There are a number of ways you can try to achieve this.
Some people like to pierce the stone with 4 toothpicks, suspending it over a cup of water. The base of the stone should touch the water.
Place the stone and water in a warm place. Ideally temperatures should be above 65 ℉. Change the water in the cup regularly. Roots should appear within 6 weeks. Once roots have formed, plant the stone in a pot filled with potting soil or peat free compost.
Suspending stones over water is a popular germination method.
An easier germination method is to simply place the stone on a sunny windowsill. Check the stone regularly. When it starts to split, plant in a pot.
The final germination method is to simply plant the stone. Plant one stone per pot. Each pot should be large enough to hold the stone and filled with a moist, fresh compost. Place the pot in a warm but dark position. Keep the soil moist, don’t allow it to dry out. When shoots appear, move the pot to a lighter position. Continue to regularly water.
Where to Position your Seedling
If you are growing the avocado tree undercover, or as a houseplant try to find a warm spot for the plant. While they can tolerate temperatures as low as 50 ℉, exposure to cool temperatures can slow growth. The avocado tree does best if it is kept warm. In the winter a lack of humidity can cause leaf drop. As long as the plant is otherwise healthy the leaves should grow back as temperatures warm in the spring.
Like the banana tree, the avocado tree also likes lots of light. Planting in a position that is too dark can cause plants to become leggy.
Transplanting and Repotting
The best way to gauge when to repot your plant is to assess the rootball. Roots emerging from drainage holes in the bottom of the soil is a clear sign that the plant is outgrowing its container.
To properly gauge the condition of the root system you need to remove the plant from its pot. To do this, turn the pot upside down. With one hand over the soil use your other hand to squeeze the pot several times, this loosens the soil. You may need to run a dull knife around inside of the pot to loose the soil. Carefully slide the plant out of the pot. If there are more roots than soil then it is time to repot.
Repotting is best done in early spring before new growth begins to emerge.
Grow seedlings on in containers, regularly repotting into a larger pot each time it begins to outgrow its home.
Select a pot slightly larger than the one currently holding the plant. It should be clean and have plenty of drainage holes. If you are transplanting for the first time after germination, select a pot at least 10 inches wide and twice as deep as the root system. An unglazed terracotta pot is ideal because the porous nature of the material encourages excess moisture to drain away. This helps to prevent problems such as root rot that are typically caused by plants sitting in wet soil.
Remove the plant from its current container. Brush away any soil and inspect the root system. Gently untangle and clip away roots that are dead and rotted. Once you have cleaned up the root system, repot the plant in the same soil. To do this lay a thin layer of potting soil on the bottom of the pot. Plant in the center of the pot. Fill in the gaps around the plant with more fresh soil. A potting mix blended with sand to improve drainage is ideal.
As we have already noted, the avocado tree won’t survive exposure to colder temperatures. In USDA Zones 8 and lower they are best grown either in a greenhouse or as a houseplant. Growers in warmer zones can try growing the plants outside. In mild climates this is best done in a sheltered spot, where the plant is protected from cold winds. Planting an avocado tree outside is largely the same as planting any other fruit tree.
Following germination, and once the sapling is large enough, harden it off before transplanting.
As you harden off the plant, take the time to properly prepare your planting site.
The ideal planting sight should be filled with natural light. The soil should be well draining. Work sand, gravel or organic matter into heavy soils to improve drainage. The soil pH level should be 6.0 to 6.5 but plants can tolerate slightly more acidic or alkaline profiles.
Your chosen planting space should be 8 to 10 ft from any buildings or other potential obstacles. You should also space specimens at least 30 ft from each other. Finally, when selecting your planting space remember to check what is overhead. You don’t want to plant a potentially tall specimen directly underneath any power cables.
Use a good shovel to dig a hole 3 to 4 times the diameter of the container and 3 times as deep. Remove any turf grass from the planting site to a 10 ft diameter around the planting hole. This area must be kept clear and weed free. Covering the exposed soil with a mulch helps to deter weeds from emerging.
Position your sapling in the center of hole. It should sit level at the bottom of the hole. Backfill the hole, take care not to disturb or knock over the sapling as you plant. Don’t add any topsoil, fertilizer or compost. This helps plants to acclimatize to their new conditions.
Be careful when transplanting, the root system of the avocado tree is sensitive. Too much handling can cause shock.
After planting mulch the soil around the trunk and water well.
Water your sapling daily for the first week, then once or twice a week for a few months afterwards. Continue to water twice a week if it doesn’t rain for a week for the first year.
Avocado Tree Care Tips
While for most growers the avocado tree is best grown undercover, this doesn’t mean that it won’t enjoy being outside on a warm, summer days. Placing the plant on a plant caddy enables you to easily move it outside and around your home. Just remember to bring your avocado tree back in before temperatures fall.
Regularly water the soil around your plant. As soon as the top soil feels dry, give your plant a drink. Overwatering can cause foliage to curl up or soften. Underwatering causes foliage to wilt.
When watering during the growing season use a hose to water the soil deeply, thoroughly soaking the root system. During the winter months growth slows. This means that plants may not require as frequent watering.
Regularly water growing specimens.
Only fertilize your avocado tree during the growing season, this lasts from February until September.
Apply a dose of liquid fertilizer every 2 weeks during the growing season. Alternatively, apply small doses of water soluble or granular regularly throughout the growing season. You can also use a fish emulsion. This should be applied once a month during the first year.
If you are growing your plant undercover you may wish to use one of these natural fertilizers instead of a chemical solution.
Specimens growing outside also benefit from a dose of ammonium sulfate amendments. These can be applied to the soil during the growing season. In the first year apply half a cup or 120 mil once a month. This can slowly be increased to 1 cup a month. Once the specimen is around two years old, you can apply 2 cups of amendments a month.
Supporting Growing Plants
Small or dwarf cultivars don’t require support. Taller specimens, certainly anything over 5 ft will require staking. Supports are best installed during planting.
If you have planted the avocado tree outside the Dalen Tree Stake Kit is an easy way to support the growing plant. You can also make your own support with a sturdy piece of wood or bamboo.
Use nursery tape to tie the trunk as low as possible without it flopping over. Weaker trunks may need to be tied to the support two or even three times. Regularly check the ties to make sure that they are still supporting the growing avocado tree. They will require adjusting as the plant grows.
As well as providing some support you may also need to prune the tree to encourage strong, healthy upright growth.
Pruning your Plant
A little regular pruning and training helps to promote healthy growth. As well as helping the plant to maintain a healthy shape it also helps to keep plants pest and disease free.
Light pruning can be done at any time. Heavier pruning is best done either in late winter or early spring. Prune away dead wood in spring. If you have planted a grafted dwarf specimen, use a garden scissors to remove suckers that emerge from the rootstock.
Prune indoor and outdoor specimens the same. To control the height, cut the tallest branch from the tree. Do this every year. To control the width, remove the longest most unruly branch. Each year prune away another branch. When pruning, never remove more than one-third of a branch.
To encourage branching prune stems back by 7 inches. Pinch out emerging branches when they are roughly 8 inches long to promote additional branching and bushy growth.
The main aim of pruning, particularly when the plant is young, is to make sure that the canopy is balanced. This means removing side branches that are too large when compared to the trunk or leader. Any branch more than a third of the size of the trunk is too large. Failing to remove this can cause the canopy to become too heavy on one side or too large. These branches are best cut away or pinched out when they are young, ideally as soon as you notice them.
While most of the time side branches should be removed, if a particularly vigorous side branch is naturally aiming upwards you may want to leave it in place and allow it to become the new trunk.
If you are growing the plant for its fruit you may want to remove low hanging branches. Fruit forming on particularly low branches may contact the ground. This can cause them to rot or become diseased. Otherwise you may want to keep the lower branches in place. Lower branches prevent the wind from blowing mulch or leaf debris away and also protect the trunk from becoming sunburnt.
Will my Plant Develop Fruit?
It can take up to 10 years of continuous growth before an avocado tree begins to develop any fruit. Even then this may only occur in ideal conditions.
If flowers emerge, hand pollinating encourages fruit to set but is not necessary. Most avocado tree varieties are self-fertile. This means that you only require one plant for fruit to form.
Avocado tree flowers have both male and female parts. Interestingly, the flowers open twice. On the first day the female parts of the flowers emerge, on the second the male parts are prominent. When presenting as female, a tall stigma emerges from the center of the flower. Male flowers have numerous upright parts, known as anthers.
Flowers require pollination for fruit to develop. Many varieties are self fertile.
When the anthers start to look tattered it is a sign that they are releasing their pollen. When this happens touch the male flower anthers to the female stigma. Do this lightly to avoid damaging the blooms. This is a quick and easy way to ensure the flowers are pollinated but pollination can occur without intervention.
Harvesting and Storing your Fruit
If fruit does emerge, allow it to develop on the plant. When the fruit reaches its full size harvest and ripen in a warm, dry place for a few weeks. Ripe fruit can be stored in a refrigerator for a couple of weeks.
Common Avocado Tree Problems
When placed in a favorable position and correctly cared for these are pleasingly low maintenance, problem free plants.
If growing undercover various insects can be a problem. These include:
- Red Spider Mite.
Treat infestations with an insecticidal soap, which you can easily make at home, or neem oil. Affected plants may require repeated treatments over the course of a few weeks to fully remove the infestation and any eggs the pests leave behind.
A number of different pests can target the foliage of this plant.
Be careful not to overwater your plants. This can cause root rot. If you are not sure whether to water or not, allow the soil to dry out a little more before watering. A soil moisture meter provides a reliable way to work out when to water your plants. The Gouven Moisture Meter provides a simple but effective way to monitor the moisture content in both outdoor areas and pot plants.
Yellowing foliage can indicate too much water or poor draining soil. Amend the issue quickly to prevent root rot.
Laurel wilt can be an issue if growing outside.
If your plant does produce fruit, don’t worry if some of it drops. This is common and not necessarily a sign of disease. The avocado tree typically drops some fruit because it produces more than it can support. Thinning out the fruit as it forms can help to prevent this.
Small, walnut size fruit dropping from the plant is also perfectly normal. A thin line may be visible on the stem where fruit separates from the plant. This indicates that it is simply excess fruit drop and not caused by a more serious, underlying issue.
Stress can cause fruit to drop. Both under and over watering can cause water stress. The plant’s feeder roots lie close to the soil, stress or damage to these can also cause fruit to fall. To prevent this let fallen leaves stay on the soil or apply a layer of mulch. Either provides a protective barrier.
Fruit drop may also be caused by too much nitrogen. Avoid applying nitrogen heavy fertilizers from April until the end of June.
Finally, avocado thrips and mites can cause drop. Thrips cause scarring on new fruit near the stem end at first before spreading over the fruit. Pest sprays or organic solutions can be used to cure infestations but once fruit is damaged it is often too late to save it.
Adopting good growing practices, and growing in a favorable position, helps to keep plants healthy and productive.
Warning the avocado tree can be poisonous to dogs and birds as well as livestock because it contains persin.
Attractive and pleasingly low maintenance, the avocado tree is a versatile plant that can thrive either undercover or, in warmer temperatures, outdoors. While the plants are mainly grown for their ornamental interest, with a little extra work and some luck, you may also be able to harvest your own fruit.