I use Osmocote and Foliage Pro 9-3-6. I incorporate the Osmocote into the mix, and then I sprinkle on top of the mix every 4 months. During the prime growing season, I fertilize with Foliage Pro once a week (Fertilizer Friday) at full strength when I fertilize my Citrus.

I think your Avocado is ready to be potted up this Summer. It could easily handle a container twice the current size. Also consider your potting mix. I recommend something with excellent drainage so that you can water and fertilize during the Winter without worrying about salt build-up or root-rot.

Josh

Thanks, Josh—this is really helpful.

Is there a specific Osmocote product that you use? Is Osmocote Plus different from regular Osmocote?

Yes, the old Osmocote Plus included Calcium.
But I don't think the new product includes Calcium. That doesn't really matter to me because I have the Foliage Pro, which does include Calcium. The Osmocote is really just back-up for when I miss a week here and there.

The Osmocote that I use is the 19-6-12, 4-month slow-release formula. I like the 4-month formula because I can be fairly sure that it's all used up within 3 months, due to my frequent and copious watering. It's easy to add more...not always so easy to take away. That's why I prefer the 4-month over the 6 or 8 month formula.

Josh

I don't use the CRF in my soils very often, but if I did, I'd also use the short term product in a ratio as close as possible to 3:1:2, like Josh's 19-6-12. You're up on what the difference is between a fertilizer's RATIO and its NPK %s? 24-8-16, 12-4-8, and 9-3-6 are all 3:1:2 ratio fertilizers.

Al

To chime in, Osmocote Plus has micronutrients in it, the regular does not. Avocados need the micros like boron otherwise they get holes in the leaves. You can also get Dynamite at Home Depot, pretty much the same thing.

Of course, needing the minor elements isn't something unique to avocados, all plants need a full compliment of the essential elements, preferably in a favorable ratio, to grow normally.

I think the following objective outline of what a supplementation program for containerized plants should include is worth considering as a framework for fertilizing containerized plants, and it's very easy to implement.

The
goal for fertilizing containerized plants can easily be described. Ideally, we
would work toward ensuring that all the nutrients plants normally secure from
the soil are in the soil solution at all times, in the ratio at which the plant
actually uses the nutrients, and at a concentration high enough to ensure no
deficiencies yet low enough to ensure the plant isn't impeded in its ability to
take up water and the nutrients dissolved in water. This goal is easily
achievable using one water soluble synthetic fertilizer. You CAN use organic
forms of nutrition, like fish/seaweed emulsions or various types of meal, but
that makes it much more difficult to achieve the goal.

Al