Prune the main stem immediately below any of the 4 most distal (farthest from the roots) leaves. I would say immediately below the 4th leaf from the top. Typically, you would prune immediately above a leaf, but in this case, you might want to use the dead stub as a stake to temporarily tie a new leader to so it grows more or less vertically.

How you would typically prune:

When you make the pruning cut, you'll have new branches growing in the axils (crotches) of leaves immediately proximal to the cut. You want to leave a stub, by cutting below the leaf above, so you can tie the new branch you see growing (even though it LOOKS like a leaf, you can be sure it's a branch) in the upper leaf's axil above.

Tie your new leader to the stub with a strip of cloth while it's very new and flexible. The branch I tied up (below) formerly formed about a 100* angle with the stem segment above and about 80* with the lower stem segment, so you can see I bent the soft branch more than 90*:

Then, start pinching religiously, and get into the habit of removing all long growth that occurs over the winter. One of my projects over the weekend was to bring all my tropicals and sub-tropicals out of the basement and site them outdoors. This is a Ficus retusa I pruned today:

A closer look:

This tree, which I grew from a cutting, is at least 10 years old - maybe as old as 15 - I don't remember. It takes time to build a fat trunk with rapid taper - should be ready for a pot other than the plastic training pot about this time in June 2020. I took it WAY back to only 2 leaves on each branch. I'll get a branch from the axil (crotch) of every leaf, and new buds will break all over the tree. Fun stuff.

Al

Re your question about enhancing the color, the only real solution to that is light. Mine sits in a southwest window and gets ~7 hours of mostly direct sun. I took the pic below at 11am this morning, so only the leaves right up near the glass were starting to get full light, but it takes the southwest exposure and heat just fine. (It was 101F today, mid-80s and 52% humidity inside the window.) The trick is acclimating them. If you have a window or patio you can move yours to that has more light, take a week or ten days to slowly ramp up the plant's direct sun time. Then don't freak out if your first new leaf is smaller than the ones before -- that happens when a plant isn't having to make huge leaves from desperation for light in a dim room. On mine, after an initial small leaf, the ones that came later have generally been about the same size as the older leaves.

This works for darkening up "burgundy", but I don't know about other cultivars. Are you sure yours isn't "robusta" instead? Maybe someone who knows more about F elastica varieties can chime in.

If you want to have many branches of a big leaves plant, first make sure the root performance is sufficient to support many branches growth. Wait at least the trunk have nearly an inch in diameter. Give it better light so it can build stronger root, bigger, darker leaves, and closer stem internodes, then you can try pruning. 2 plants from your pics both haven't got enough light. 2nd pic brightness is edited. If you force to prune yours now, from 5 buds, maybe only one that keeps growing, the rest will stunt and eventually dry.

That's simply not so. You cannot force the plant to grow a massive amount of rootage so it can support a huge spurt of top growth when you wish it to happen. Root growth always precedes top growth by a margin sufficient to support the new top growth. It's much like a game of leap frog - the roots grow, then top growth until it reaches the limits of what the roots can support, then more root growth ...... Pruning when the plant has high energy reserves, is growing robustly, and photosynthesizing ability is at or just after peak (summer solstice) will ensure the most enthusiastic response to the pruning cuts, regardless of the tree's o/a size, trunk caliper, or age.

Al

one related question.

I have a Burgundy three stem, I leave it outside west facing, for about one month now. And the new leaves grow very slowly and remain tiny when fully developed. Sun is not too bright we are still may and it gets full light just 4-5 hours a day. I water it after i check it with a tell so watering is not the issue.

Rubber tree leaves size much related to stem size. And stem size related to root performance and total branches it have. FLF, rubber tree, and other small leaves ficus have different characteristics.

Nope. Every plant have similarity and uniqueness. You need to have and grow them at least 2 years to recognize their grow pattern and characteristics. Species by species. For F elastica, the leaves size always related to stem where the leaves attach. Even long stem.. many leaves, if the stem is small, the leaves also small. F elastica have longer consistency in leaves size, similiar with premna microphilla or streblus asper which is used as bonsai specimens for its uniqueness. F benjamina different with f elastica. F benjamina leaves will grow big again if the stem lil bit longer no matter the stem size is. Even in same family, same genus, every species have uniqueness... If you have F elastica, you can compare yourself relation between leaves size and stem where they attach. It's linier.

My question got a little de-railed, or got misunderstood.

This is the thing.

I have a great Rubber plant, nice normal size leaves.

I place it outdoors, it's starts producing stumped growth tiny leaves. Like 1/4 the size of the leaves it produced when indoors.

What is more the new growth is very slow.

So I got an opposite effect, instead of vigorous growth.

My question: could it be that being outside hurts the plant?

That's some problem with big leaves ficus. For small leaves ficus, older leaves will simply fall and new twigs/leaves start growing vigorously as replacement. They adapt much faster. Big leaves ficus adapt differently. They will reduce or stop growing for a while. Green soft stems turn to brown, and in a very drastic changing environment, most of the older leaves will fall. Even their growth will back to normal and grow faster eventually, moving big leaves ficus outside without uv filter only worth if you wanna move it permanently outdoor to become garden tree if your climate allowed, otherwise keep it inside, or use uv filter to prevent long period of adaptation process.

The science is pretty basic: a plant needs x amount of energy to support itself. If there's only limited light, the leaves need to grow quite large to collect enough photons to photosynthesize the energy it needs to live. OTOH, if there's a ton of light available, the leaves can remain small while photosynthesizing the same amount.

If you want big leaves, move the tree back to a shadier spot.

Based on what I've observed, I can say that what Gudang said rings completely untrue. I've been charged with restoring the health of many rubber trees that have been pried out of dark corners, and haven't found their growth response to be anything like he describes. Nor have I found their response to be any different than smaller leafed varieties of the genus, except that they are slower to grow. I often prune top and roots of reasonably healthy rubber trees brought to me and site them in full sun on the same day, knowing the leaves will burn, drop off, and very quickly be replaced by a new flush of foliage perfectly adapted to whatever light conditions prevail where the tree has been sited. I'm not advocating that you follow suit, but I do this with other people's trees and don't worry about whether or not the tree will quickly recover. I can't remember the last time I lost a ficus that wasn't already trying to break down death's door. It's not that I don't worry about other folk's trees because I'm irresponsible; rather, I've repotted and revitalized so many rubber trees w/o loss that concern would pretty much be the equivalent of much ado about nothing.

Al

I was suspecting what Sage said. Having lots of light even smaller leaves get the job done. Thanks to all

For visual reference

I just sharing, Al, since i have many and grow them day by day. I even make an experiment to reduce their leaves as much as i could. It grow smaller than f benjamina leaves, but since the leaves size directly related to stem size, in this size the buds prone to dry and grow very slowly.

In normal condition, even if it grow outside under direct sunlight all day, the leaves still grow big.

FLF moved outside, just about 4 hours direct sunlight daily. Since it's variegated, the effects much worse compared with the green var. Newest leaves size decrease significant, older leaves got burned, damage, and some fall.. and it grow very slowly. Newest 3 leaves grew 2 months ago. Normally, it grow new leaves under 2 months, maybe almost every month. Even small, but they adapt, not get burned or fall.

Leaves size decrease is just part of adaptation process. Some need longer time. Ficus is group of plants that have similarities in flower shape, which is hidden inside the 'fruit' . Their habitat, growing habit, or shape are so vary one and another. Lyrata.. pumila.. too many of them to simplify and make generalization about their growing pattern.

Yeah, that looks like mine. The first tiny leaf appeared after the first day of acclimating it to the SW window. It was there for one hour before being moved back to its usual SE window. That brief jolt of intense autumn sun was enough to do the job at my latitude.

It's repeated a couple of times since, but I wasn't tracking what was going on. At one point I moved it from a stand up to a table. And winter tends to be six weeks of rain/overcast here, so when the sun came back in February, I think that corresponds to at least one of the little leaves. But it's only a few out of four dozen or so total leaves on a healthy tree. I'm not worried.

For FLF, light intensity will be direcly effect leaves size as part of its adaptation process. So in a long single stem, if you grow your plant indoor, FLF leaves size will vary. Some smaller, some bigger because light intensity isn't equal on all side and the leaves size isn't much related to stem size. F elastica is different. In a long single stem indoor, the leaves will relatively uniform, same size.

FYI, there's 2 kind of trees in tropical rainforest climate. One that grow fast on sunny season, and the others are growing fast on rainy/cloudy season. Big leaves ficus are on the 2nd part. They love bright light, but not an intense everyday full sun. Most people on 4 seasons climate think that tropical tree will love bright direct sun... No. Not like that. In fact, in sunny season, most tropical trees reduce their vegetatif growth. They start flowering and produce fruits.