Do you mean crabapple? If so, what variety?

"I want to minimize the time it takes them to fill out and get a lot more bushy."

"Aside from water, fertilizer and time"

With nature, you really can't get something for nothing. As a generalization, most trees plants in most places don't need fertilizer. There are exceptions like the sandy soils of Florida. If you try to speed them along by over-fertilizing them, you will most likely pay the price down the road.

Time, i.e., patience, is really what you need here. Trimming will just reduce their photosynthetic capacity, and thus their ability to grow.

I hadn't heard of crabwood so I looked it up. Seems to be a tropical species.

I am in South Florida, near the coast (Boynton Beach). The Crabwood (Gymnanthes Lucida) is native to South Florida. They were in 7gal cans when planted with fairly substantial root ball. Big hole with earth and MG tree&shrub soil mix. The ground here is pure sterile sand pretty much.

The trees have fairly long branches for their size. I was thinking a little nipping here and there would cause them to grow some more brances rather than the ones there just getting longer - but I was just guessing.

pruning stimulates bud break behind the pruning cut. Indeed, many nursery frown trees are tip pruned to develop a full crown, and a new leader selected.

I would say I hesitate to recommend this unless you know a thing or two about plants and how they grow (which is different from just growing plants), but...you knew there was a but, just had to be...crabwood is often used as a hedge. I'll assume that since you got multiple and want them to get bushy as quickly as possible, you want a hedge. Hedges get pruned. Or they grow in over time.

If you are impatient, a little tip pruning will do the job. Or relax, and let nature take it's course.

By the way, for the record, if you want a case study in group think, ask a question on the gw about tip pruning or fertilizing.

hilarious...I just thought someone new to gardening was riffing on "crab apple". Glad I mentioned that exception about Florida!

"i am completely baffled by these repeated questions about how i can cut
off parts of the trees to make them grow faster .. it just seems so
counter intuitive to me ..."

true

"By the way, for the record, if you want a case study in group think, ask a question on the gw about tip pruning or fertilizing."

not sure that more than one person repeating the scientifically validated and accepted, experience-proven advice of the era is the same as 'group think'. And besides, there have been plenty of arguments here about that topic over the years. What else is 'group think' to you? That the Earth is round?

Thanks for the botanical name. Turns out that the Crabwood I found is a different species. Shows you how important it is to use the scientific name, rather than the common one, if you want accurate information.

Do you want a formal hedge or a loose natural looking screen?

loose natural looking screen