You say you are in a 9(b) climate zone -- you will need to protect your avocados from winter frosts. Some varieties are more cold hardy than others, but if it goes below 30F, you will be losing all the leaves and having it resprout from the base. Given that it takes a good 6-8 years for a tree to start bearing, you don't want to be knocked back to year 1 to have to start all over.
Avocados are grown in both Florida and California, so they can take wet or dry climates as long as they get sufficient water. Avocados have similar fertilizer requirements as citrus, probably because they are both trees where the crown comes down to the ground to exclude other plants. They get most of their nutrients from their own decaying leaves, so don't be thinking about companion planting them with some type of legume. I have grown nasturtiums and cilantro in the same pot as my avocado trees, but while they tolerated these companions, they seem to be happier when alone.
P.S. The store price is only indicative of how difficult they are to pack and ship, not to grow. The two years I lived in Santa Paula, CA, I never paid for an avocado. If there wasn't one ripe in the back yard, I could check the trees along the train tracks south of town, or just bicycle around town. An observant bicyclist cycling around town could easily come home with a sackful, picking up whatever fell. Ventura County produces about a quarter of the U.S. production of avocados.
As far as frost protection, the outer leaves form a canopy that gives a couple degrees protection to the inner leaves, so knowing that, you can toss a bedsheet over them on nights with freeze warnings and get even more protection. Against a south facing wall, with a bit of cover, you would probably be good down to 20F. Too bad it got down to 12F here back in January. But they are looking good now!
Avocados need perfect drainage if not, they die immediately. The most cold hardy avocado is Bacon.
My bacon survived last winter without further protection but it only went to -1 C or so and I planted it in autumn.
Daley's nursery website has a lot of information:webpage
Depending on your climate you need two trees of different groups.
In the SF bay area it's pretty easy to grow avocados. There are a few important things to know: 1) the types of Avocado and 2) growing conditions.
1. There are three general types of Avocado tree -- Mexican, Guatemalan, and West Indian. Guatemalan varieties are the kind most people (at least here in California) are familiar with -- they're creamy and rich. Mexican varieties are smaller, with thinner skin (sometimes edible) and sometimes are good tasting. West Indian varieties are large and watery. Guatemalan trees are very frost intolerant while Mexican varieties are more frost tolerant (for example, the Mexicola variety can handle down to 22 F). Nobody in California grows West Indian varieties.
Avocados don't grow true to seed, so growing it from a seed (unless you plan to graft it yourself) isn't really worthwhile. So buy a grafted tree from a nursery. If you live in a part of the bay area that's coastal and has minimal frost (e.g. East Bay from Fremont to Richmond, San Francisco, San Rafael, etc.) then a Guatemalan variety is a good bet -- Reed is a good choice, as is Lamb Hass, Hass, Pinkerton, and a few others. If you are in a less coastal area, one that gets more heat in the summer and frost in the winter (like San Jose, Palo Alto, Morgan Hill, etc.), a hybrid Mexican-Guatemalan variety like Fuerte is a good choice. If you're in a spot that gets a lot of frost (like Santa Rosa, Napa, Petaluma, etc.), then go with a Mexicola.
2. Avocados like a mostly-sunny to sunny spot, with as little frost as possible (so not in a low spot) and in a spot with good drainage. They don't really fruit in containers, so it's not worth trying that route. The best approach is to dig a big hole to loosen the soil but then just push the soil back in, and plant the tree so it's about 6-12 inches above the natural soil grade. Heavily mulch the mound with tree trimmings and leaves and such, and keep any weeds or grass or other plants away from the tree. In the summer the trees can be watered 1-2 times a week -- deep waterings are best. In the winter there's no need to water -- the main danger is root rot if you have bad drainage. As the trees mature you can water less frequently.
Some people talk about the need for cross pollinators -- this is more true in Southern California and Mexico. It's not that important in the bay area. Reed is known as a good self-fertile variety, but most will fruit without another tree here.
Cassie Langstraat wrote:how do you ensure good drainage?
Drainage is not a problem in California. I know that's a broad brush statement, but I really can't think of any swamps that I have seen in California. Ballona creek in Los Angeles county? Even that only has water trickling through it a few months of the year. The south part of San Francisco bay is more marshland than freshwater swamp.
For there to be drainage problems, you need to have a clay hardpan that keeps water from draining away plus rainfall that is well in excess of the evaporation rate. California may have plenty of clay hardpan areas, but most of the state, with the possible exception of the area around Eureka has such a negative water balance that it's never going to get swampy and anoxic.
More importantly though is root-rot, caused by the fungus Phytophtera, which gradually kills the trees. Here in southern California I can see many, many avocados with large portions of their crowns totally dead, with skeletal branches reaching up to the sky. All successful avocado plantings need to be on rot-resistant rootstock. That's why good drainage keeps being mentioned in these posts.
Michael Qulek wrote:Have a clue! I've had trees die right in my front yard because of poor drainage, from my sprinkler system. You don't have to be in a swamp to have poor drainage.
This is "poor drainage":
Anything that can be fixed with a shovel and 15 minutes is not "poor drainage", it's "improper planting".
I get to -10F so my avocados have to come in for the winter, it's believed that an ESTABLISHED Mexicola Grande can survive around 22F for very brief periods (it won't be happy and it'll dump all the leaves). Mexicola is a smaller tree so I hope to be able to keep it trimmed down. It won't be happy though and will reportedly give me less of a yield but. Also another note that slightly potbound produce more fruit. SLIGHTLY. And that in about 8 years of production and having to uppot, your potted Mexicola will get too big and you will have to start over. If you can get the below graft to give you a shoot, propagate that, then graft some of the top to it; you could keep going. (yes I know, a lot of work and not for the really faint of heart)
Since my teens I have done grafting, air layering, and various other propagations and had my share of stellar failures. Still.
Cassie, if you can espalier your avocado to a protected south exposure with lots of mass (such as a house) and provide for some sort of temporary greenhouse or cold frame type cap for the cold season, you could probably grow yours outside in 9b (I have a friend in the Bay area, that is a 'mediterranean' climate and you can see snow and temperatures around low to mid 20's in winter). Invest in a good floor dolly for your avocado pot that can take up to about an 18" to 20" pot and some straps for two man lift of said pot for moving in and out. You should be able to maintain a tree under 7' with the pot included in house. Be prepared to play Bee to get a good fruit set. Don't take it personally but you can cry and have a big glass of wine and some ice cream if your tree pouts and dumps leaves (that always makes me feel bad, my Sycamore Figs do it to me all the time, they're three times as picky as I have to bonsai them to keep them, else they are 50' trees!).
This thread is kind of old, so please let us know how your endeavors are going, Cassie.