05/02/2021
A Complete Guide to Hass Avocado Trees
Hass avocado trees yield delicious, creamy, nutty fruit and account for 80% of the avocados eaten worldwide.
Hass avocados are the most popular avocados out there. According to Smithsonian Magazine, these rich, creamy, pebble-skinned fruits account for 80% of the avocados eaten worldwide.
While farmers and grocery stores relish these fruits for their impressive shelf life, there’s nothing better than a home-grown Hass avocado. With the right conditions and a little work, your Hass avocado tree will be ripe for success—bearing nutritious fruit in about five years and looking stylish the whole time.
Hass Avocado Trees at a Glance
Most popular commercially grown avocado tree
Self-pollinating
Green leaves year-round
Fruits in five years
Cold-intolerant
History
The Hass avocado tree has a compelling history. What is now the most popular avocado in the world was created by mistake but took off like wildfire.
Before Hass avocados hit the scene, the Fuerte avocado—a milder version descended from earlier cultivars in Mexico and Central America—was the most popular. By the 1900s, Fuertes had spread to the US.
Postman and budding horticulturist Rudolph Hass thought he had purchased Fuerte avocado seedlings in the 1920s. After planting them, the tree didn’t fruit for a long time. When it finally did, Hass discovered a bumpy, thick-skinned, rough-textured fruit unlike what he’d expected. Despite his urge to chop the tree down, his children convinced him to keep it—fans of the nutty, creamy fruit. In 1935, Hass patented the Hass avocado. Every one since is a descendant of that very tree, which died in 2002.
Appearance
Hass avocado trees are dense evergreens with glossy, leathery leaves that have a vein-like pattern. They can grow up to seven feet tall in a container and up to 30 feet when planted in the ground. On the tree, Hass avocados have green skin. Once harvested, these skins turn nubbly and dark purple-black. The fruits are heavy, weighing between 200-300 grams.
Planting
When you decide to plant your Hass avocado tree, make sure to buy your seedling from a gardening center. Trying to plant a pit from a store-bought avocado won’t work.
The best time to plant your Hass avocado tree is when the soil has warmed, Remove any turfgrass, weeds, or debris within a 10-foot diameter of where you dig your hole. Dig a hole about three times the diameter of the seedling’s container and 3-4 times as deep. It’s important that you don’t plant your tree too deep, as avocado trees have shallow roots.
Take the seedling out of its container and place it gently into the hole. You want the root ball to be slightly above the level of the surrounding soil. Backfill the hole and tamp down the soil gently. Adding fertilizer or compost is not advisable, because you want your tree to acclimate to the soil as soon as it can.
You’ll need to water your newly planted Hass avocado tree every other day or every three days for the first week or so, and then twice weekly for the next few months.
Growing Conditions
Hass avocado trees can be a little tricky when planting due to their sensitive roots and moisture requirements but are overall low maintenance once established.
Soil
The ideal soil for Hass avocado trees is loose and loamy or sandy, with a pH level no higher than 6.5. Drainage is critical, as the feeder roots are close to the surface and sensitive. If there is excess moisture, your Hass avocado tree might suffer from root rot.
Heavy clay is the worst for Hass avocado trees, but if you have no other choice, create a raised bed or a mound with a 3-5 foot diameter to plant the tree on.
Watering
When your Hass avocado tree is newly planted, it will need to be watered every two to three days. Before watering, always make sure the soil isn’t already very moist. As the tree gets older, you can reduce watering to once a week. After you’re done watering, you want the top two inches to be moist.
Soil
The ideal soil for Hass avocado trees is loose and loamy or sandy, with a pH level no higher than 6.5. Drainage is critical, as the feeder roots are close to the surface and sensitive. If there is excess moisture, your Hass avocado tree might suffer from root rot.
Heavy clay is the worst for Hass avocado trees, but if you have no other choice, create a raised bed or a mound with a 3-5 foot diameter to plant the tree on.
Watering
When your Hass avocado tree is newly planted, it will need to be watered every two to three days. Before watering, always make sure the soil isn’t already very moist. As the tree gets older, you can reduce watering to once a week. After you’re done watering, you want the top two inches to be moist.
Fertilizing
Traditional fertilizers are designed around nitrogen, phosphorus, and potassium. But in order to thrive, Hass avocado trees also need zinc and boron. You can tell if your Hass avocado tree has a zinc deficiency because it will have yellow patches on its leaves, and nitrogen deficiencies are signaled by pale or yellow-veined leaves.
You won’t need to fertilize your newly planted tree, but about one year after planting, apply roughly one ounce every month from spring through fall. The small doses are easier for the shallow roots to absorb.
Pollinating
Hass avocado trees are self-pollinating, but if you want a more plentiful harvest, consider planting another type of avocado tree. Avocado trees fall into two categories of flower types, A and B, which dictate how they pollinate. Each avocado tree has the parts for both male and female genders, but they are active at opposite times of day.
Hass avocado trees are type A, meaning that they flower from February through May. When the flowers first open in the morning, they are female until they close in the afternoon. The following afternoon, they reopen as pollen-producing male flowers. So, Hass avocado trees can be categorized as somewhat self-pollinating.
Introducing a B-type avocado tree, like Zutano, can boost the amount of pollen, ultimately yielding a bigger harvest. Cross-pollination is achieved easily because type B avocados’ flowers are female in the afternoon and male the next morning, giving them a complementary schedule.
Cross-pollination works best at about 75 degrees Fahrenheit.
Harvesting
Hass avocado trees will start producing fruit in roughly five years. The avocados will not begin to ripen until you pluck them from the tree, so leave them hanging until you need them.
Once you pick them, leave them out at room temperature. They will soften over the course of one to three weeks, and the skin will transition to a dark purple-black shade. Once they are soft, you can store them in the refrigerator for a few days.
Pruning
Hass avocado trees don’t require much pruning, but you may want to prune in order to remove broken or damaged limbs, maintain the tree’s height, or refine its shape. You should clip off any growth below the graft joint, like small leaves—it is likely from the rootstock and will not produce a Hass avocado.
If you want, you can cut terminal buds to encourage the growth of new lateral branches. Trimming the tips of the tallest branches will cause the tree to grow wide instead of tall. Do not prune the tree heavily. You can protect a newly planted tree from sunburn by washing its trunk with a solution of equal parts latex paint and water.
The best time to prune Hass avocado trees is when they are dormant in winter, and growth is slow. Do not prune after February.
Risks
Hass avocado trees are susceptible to various diseases and pests.
Diseases
Phytophthora, which causes root rot, fruit rot, and collar rot, spreads through watering. To help prevent this issue, make sure you have excellent soil drainage and keep your tree dry. Unfortunately, once phytophthora sets in, there is no way to save an established tree.
Avocado black streak causes cankers, but its own cause is unknown. It creates cracked, black lesions on Hass avocado tree trunks and branches. Proper irrigation can help you avoid this issue.
Pests
Common pests that disturb Hass avocado trees include avocado mites, avocado brown mites, and persea mites. You can treat all of these with neem oil. You can prevent mealybugs and avocado thrips with ladybugs.
