A southern California staple, the Hass avocado tree is known far and wide for its fruit. And why wouldn’t it be? Flavorful and rich, these fruit trees produce fruit which is rich and flavorful, filled with healthy oils. It’s served sliced atop toast, rolled into sushi, and mashed to create guacamole for our Mexican fare.
But how did postman Rudolph Hass stumble across this gloriously-creamy, rich and decadent variety? Completely by accident, it turns out. The resulting fruit has swept the world, accounting to nearly 95% of US sales and 80% elsewhere.
Best of all, you can easily grow this tree yourself. A quick-bearing variety, you’ll often have produce by the tree’s second or third year. Let’s talk guac — or at least, how to grow your own Hass avocados!
This post is sponsored by Fast Growing Trees, who provided a Hass tree for this care guide.
Good Products For Avocado Growth:
- Neem Bliss 100% Cold Pressed Neem Oil
- Monterey Bacillus Thurigiensis
- Tanglefoot Tangle-Trap Aerosol
- Nature’s Good Guys Live Ladybugs
Quick Care Guide
|Common Name(s):||Hass avocado tree|
|Scientific Name||Persea americana ‘Hass’|
|Zone:||9-11 outdoors, can be grown indoors in zones 4-11 in container|
|Height & Spread:||Up to 7′ tall in container. Up to 20-30′ tall in ground at max height.|
|Soil||Extremely well-draining, loose, pH 6.5 or below|
|Water:||Watering varies widely by season and size|
|Pests & Diseases:||Various mites, thrips, mealybugs, ants, avocado worms. Also very susceptible to phytophthora rots, avocado black streak, some cankers.|
The History Of Hass Avocado Trees
Alligator pear, aguacate, ahuacatl — these are all names for the fruit known as the avocado. Botanically, it’s known as Persea americana.
Prior to the market domination of the Hass cultivar, the most popular version was Fuerte. This milder, larger avocado descended from earlier versions cultivated in Central America and Mexico. And, as all delicious food does, it slowly spread to other regions. By the 1900’s, avocado was quite popular in the United States.
Enter Rudolph Hass. A postal worker who had a garden, he fell in love with avocados. Due to their expense, he sought seeds wherever he could find them. The seed which produced the tree that would eventually bear his name was purchased from a man named A. R. Rideout. Hass planted the seed in his yard in the late 1920’s, planning to graft Fuerte branches on it.
Every graft he attached failed. It wasn’t producing fruit as it was still young, and Hass threatened to cut it down to replace it. His children interceded, recommending he wait and see how it did on its own.
When it finally did produce fruit, it was bumpy and dark-colored, unlike the smooth skin of the Fuerte variety. The bumpy skin was much thicker than Fuerte’s, too. One of his children tasted the oily, creamy fruit, and immediately went in to present it to Dad to taste.
Begrudgingly, old man Hass agreed that this tasted a whole lot better than his planned Fuertes. The bumpy and thick skin also protected the tender, soft flesh inside, making it easier to ship and sell commercially.
Hass’ first sales of the fruit were at the post office where he sold avocados to coworkers. He later sold to a supermarket in Pasadena, CA, and local restaurants would sweep in and buy up the produce for full retail price.
He decided to patent his variety. Arrangements were made with a nursery to sell Fuerte rootstock with his grafted Hass branches on it. Unfortunately, he only earned $5000 from his patent over his lifetime, as people would purchase a tree and then graft to other trees.
Hass passed away in 1952, but his original mother tree survived until 2002 in front of his former La Habra Heights home. It eventually succumbed to phytophthora root rot. A sign is placed where the tree once stood, and La Habra Heights still celebrates this homegrown avocado variety during an annual festival.
Hass Avocado Tree Care
Avocados are not a difficult kind of tree to grow in warm regions. They are a bit finicky about their soil and moisture, but once established they can stubbornly cling to life. Let’s talk about the ideal planting and care for them!
Light & Temperature
As should be expected with most tree species, full sun’s essential for their growth. The more light hitting the canopy, the better they will do. A fully grown avocado tree should have plenty of light hitting the leaves.
The reason California is such a popular place for growing these plants is because of its weather. Avocados are not freeze hardy. An adult, fully grown tree can tolerate temps down to 28-32°. But younger plants are going to be much less tolerant of cold temperatures. Similarly, 100°+ temperatures reduce fruiting capability, and your plants will be at risk of sunburn if it’s too hot.
Optimal conditions for your hass avocado trees are areas which have full sun and which spend most of the year between 60-80° temperatures. Keep your seedlings sheltered from high wind.
Water & Humidity
Avocados are thirsty! When first planted, your tree may need to be watered as often as two to three times per week. Check the soil first, though. A good test is to scoop up a handful of soil and squeeze it. If it holds the impression of your fingers, it has enough water. Moisture in the top 2-4 inches is ideal, as the feeder roots are close to the surface.
Fully grown trees need more water, of course. A mature tree which is fruiting can easily suck up 20 gallons of water a day. Do not expect these to be drought tolerant. You’ll go through quite a lot of water for these tasty treats!
Keep a watchful eye on the soil moisture. You’ll need to develop a watering plan that suits your climate, and it will vary month by month. This can be tricky at first, but you will settle into a rhythm.
Ironically, despite their thirst, hass avocado trees don’t like having wet feet. Muddy, oversoggy conditions can promote root rot, and they’re quite susceptible to that. These do much better with slow drip irrigation than with a deluge.
Did I mention that this tree doesn’t like wet feet? The soil has a lot to do with that. Soil that’s enriched with a lot of compost and organic matter can hold moisture easily. If you’ve got good-quality soil, you may not need to water as often. In addition, avocados are sensitive to pH levels above 7, so you need to maintain pH no higher than 6.5.
The soil itself should be loose, friable, and in the sandy to loamy range. Avocados hate hard clay soil as it just doesn’t drain well. It’s also too tough for the tender feeder roots to permeate. The feeder roots are generally in the upper 6″ of soil around the tree.
Commercial growers often amend an area that’s 1′ deep by 3-5′ across heavily to improve it. They’ll then create a domed mound of soil, 2′ in height, over their amended area and plant in the center of that. This ensures good drainage and provides the right soil type.
Mulch in a 6″ deep layer with wood chips around your tree. Keep the mulch at least 6″ away from the trunk. This helps reduce moisture evaporation while preventing weed development.
There are a list of essential nutrients which avocados require for best growth. These should always be included in your fertilizer regimen.
- Nitrogen: helps with growth and development
- Potassium: helps with growth and fruit-bearing
- Boron: helps with growth
- Zinc: needed for fruiting
In addition to these, the following list is recommended but not as essential as the above:
- Phosphorous: helps tree metabolism
- Calcium: promotes good structure and healthy roots
- Magnesium: required for photosynthesis
- Iron: overall tree health
- Manganese: overall tree health
- Sulfur: lowers soil pH to maintain tree health
Fertilize in small doses over the entire growing season. The shallow roots can more readily absorb small doses.
Newly-planted trees don’t need much fertilizer, but in the first year applying about 1oz of nitrogen on a monthly basis from spring through fall is good. Don’t fertilize from November through February. In subsequent years, go by the trunk diameter. A total of a half pound of nitrogen per inch of trunk diameter per year is essential to good growth.
A professional soil test is recommended to determine annual amounts to apply of the other nutrients. Most home soil tests do not test for anything beyond NPK. But as a good rule of thumb, applying the first four annually will be required. The other nutrients should be tested for.
Propagation & Fruiting
Hass avocados are propagated by grafting only. They will not grow true from seed.
Unless you’re skilled at grafting, you’ll want to buy a grafted seedling from a reliable source like Fast Growing Trees. This ensures you’ve got a healthy young seedling to start with!
All avocados fall into one of two flower types: type A, and type B.
Hass are type A. They flower from February through May. When new flowers open the first time, they are female until they close that afternoon. When they reopen the following afternoon, it’s as pollen-producing male flowers. This means they’re somewhat self-pollinating.
Having a type B avocado nearby can increase the amount of pollination your tree will get, which increases crop size. Type B avocados produce female flowers in the afternoon, and the next morning the flowers are male. The timing is perfect for both types to cross-pollinate.
Any new growth that appears below the graft joint should be removed when you notice it. This includes small branches or leaves. Growth below the graft is usually from the rootstock cultivar, and won’t form Hass produce.
Most pruning is for one of three purposes: to keep the trees at a certain height, to shape them, or to remove deadwood or diseased portions. Other pruning simply isn’t necessary.
When pruning for height, trim back only the tallest of the branch tips at any given time. This encourages the tree to grow wide rather than tall.
Most pruning is done while the tree is dormant in winter. As an evergreen, it never loses its leaves, but will still have a period of slow growth during the cold season. In warm climates like California, the earliest you should prune is November, but it’s best if done in late December to mid-January. Try not to prune after mid-February, as it should be coming out of dormancy then.
There are a few things to watch for. Let’s go over a quick list of the most common problems you’ll face.
New growers often report that flowers fall off the tree without producing. This isn’t uncommon, and isn’t a danger.
Watch for yellow-veined leaves or paler leaves and poor growth as a symptom of nitrogen deficiencies. Zinc deficiencies cause yellow patches between veins on leaves, and the avocados may form as round ball-like produce.
Sunburn can cause the bark to peel away from the trunk and blackening of branches. Applying a whitewash to the trunk helps reflect the heat away. If you don’t have whitewash or a flat white latex paint, you can use white cardboard instead.
Many different mites can attack your hass avocado trees. The most common are the avocado mite, the persea mite, and the avocado brown mite. All of these respond well to treatment with neem oil.
A particular kind of thrips, avocado thrips are a relatively new pest that California growers are battling. At this time, the University of California recommends using environmental controls like beneficial insects to get rid of them. They generally cause cosmetic damage to your avocados rather than permanent tree damage.
Mealybugs and ants are an evil pairing for avocado growers. Getting rid of both simultaneously is wise. A wide band of sticky material around the trunk can prevent ants from climbing the tree. Ladybugs will then handle your mealybugs while they’re keeping your plant thrips-free.
Three different forms of avocado worm exist. These are all forms of leafrollers, and they go after your produce as well as the leaves. Bacillus thurigiensis is effective against them without causing damage to your beneficial insects.
The most damaging fungus to an avocado is phytophthora. This in various forms can cause root rot, collar rot (a form of canker on the trunk) and fruit rot. In all cases, this spreads via watering. Keep trees and leaves dry. Ensure your soil drains extremely well without becoming muddy. Prevention is essential as there are no cures for phytophthora once established in your tree.
Avocado black streak is a canker-causing pathogen, but its cause is unknown. This creates black lesions on the trunk or branches which can crack and ooze sap. It appears most often after drought stress or exposure to excess salts, and can be fatal to the tree. Practice good irrigation with high-quality water.
Dothiorella canker is also common in Hass trees. These cankers are not black, but they also crack. The sap they exude dries into a white powder. Carefully scraping off the outer bark on the canker to remove it can help portions to heal. It can cause the tree to look sickly, but the trunk generally continues to survive.
Frequently Asked Questions
Q: How tall do Hass avocado trees grow?
A: Container-grown trees reach 5-7 feet. Those planted directly in the ground can reach 25-30 feet at max height. Many people opt to maintain their trees at about 15 feet tall.
Q: Are Hass avocado trees self pollinating?
A: Generally, yes. But as mentioned above, they cross-pollinate extremely well with a type B avocado. You don’t have to plant a second tree, but it will greatly increase your potential harvest.
The Green Thumbs Behind This Article: