if these plants are grown from seed from supermarket avocados, they may not come true to type, or fruit well at all…..so hope you’re not going to devote a large amount of garden space to grow them for fruit.
they look like they’re about due for re-potting into larger pots….at which time you could incorporate up to 50% coir into fresh potting mix, which will thereafter be always pretty easy to wet when watering. pure potting mix (mostly bark) becomes hard to wet sometimes.
i would also give them a well diluted seaweed solution, for a bit of pick-up.