It’s Springtime in the Monterey Bay, swallows are plying the sky and peaches are in full pink. That means frost danger is passing, and it’s nearing time to plant avocados. If you can find trees, they need to go in now to start their race against the seasons. First freezes can hit in November, and the bigger you can grow your young trees, the better chance they have of surviving the cold. From our vast experience with killing trees, we would like to offer help in avoiding the blunders we’ve committed in trying to get our trees to grow.
Starting with site prep, avos need perfect drainage. If your site falls short, you need to make it good before you put your tree in the ground. Import sandy soil if you need to, but building a well-draining mound is one way to provide drainage if you’re stuck growing on clay. Basic rule is if your tree’s roots are ever exposed to standing water, those roots will die. Best is a mound that can keep the whole root-zone above the saturation zone. Each situation is unique, so size your mound accordingly.
As you build this hill, resist the urge to load it with compost, mulch, or any other decaying organic material. Rotting plants give-off ethylene gas that will damage the new root system. Another way to inflict injury is to be rough in unpotting and setting your tree. Avocados have extremely tender, brittle roots, so merely letting the rootball fall-apart as it’s removed from the pot will severely set back, or possibly kill your tree. By all means never “break-up the rootball” of an avo as you plant it no matter how pot-bound it looks, unless your intention is to kill it. A good way to set a tree is to gently slice off the pot or grow-bag in-situ, at the proper level, in the hole. Proper level means just as deep in the mound as it was in it’s pot. Support the root-ball by backfilling the hole as you pull the bag (or pot) away from the ball. Slice at an angle so you don’t cut through roots as you cut through the pot. The less you damage you do , the more your tree will grow.
Settle the tree with a good watering, and apply gypsum and fertilizer to the top of the mound. Avos are easily killed by excess salt and nitrogen. Avoid guano, fish, or other fast release fertilizers; reach instead for slower fertilizers like feather meal or alfalfa pellets to avoid a potential nitrogen blast or salt burn. Fertilize often, supporting growth flushes with an every-other-month dose of low concentration, instead of blackening your tree with an overdose. Now is the time to employ the rotting plant material; avocados love heavy mulch.
Ultimately, it’s your tree, you can do with it what you will, but keep in mind that avocados are just waiting for an excuse to die. Bumbling along on my learning curve, I’ve done the opposite of what I advise above, and my casualties number in the hundreds. Save yourself from the same fate. Armed with a little insight and some active attention, your baby tree can stay alive and thrive and put-on the solid growth it needs before fall. With a little luck, it’ll attain the trunk diameter and canopy density to withstand whatever the winter throws at it.