Fatsia japonica. Often grown as a houseplant. It can get quite large. I'm not sure of the best way to prune, but I'm sure there's info online.

EDIT: I found this as one of the top Google results-

"Remove the oldest stems at ground level, taking out up to one-third of the Japanese fatsia's stems. Trim anytime after late winter and before the end of summer. Removing the longest stems each year reduces the size of the shrub."

And this-

"Because these plants can grow rather tall, don't be afraid to prune them back. Fatsia needs to be pruned every year to keep its bushy growth habit and glossy foliage. You can either cut the entire plant down to the ground in late winter, just before new growth starts...or to improve the appearance, trim leaf stems that extend too far beyond the plant ."

Your plant seems young, and has only one main stem, so I'm not sure you can do much to restrain it to its allotted space. You may just need to either move it, or the plants it's encroaching on.

At this point you can just cut off individual lower leaves close to the main stem that are covering and hiding the ferns.

Thanks - so I would leave the central upright stem alone and just cut the stems coming off of it? Is there anything I can do to keep the height down along with the width?

I've never grown this plant, so I'm not sure how it responds to being topped, or having the central leader cut. Most plants respond by sending out more side shoots from dormant buds. It's the normal process for making a plant more bushy and full. So taking out the leader may just make it grow wider. Hopefully someone who has actually grown the plant will chime in.

It's really too young a plant to be pruned. If you feel it is too spreading, and you need to prune it then maybe you should move it in spring to a place where it can really reach its potential, --- and plant a different shrub in its place -- something more upright or something that can be limbed up a bit, like Camellia sasanqua or Ternstroemia.

Fatsia is more like a clumping perennial blended with a suckering shrub. New growth comes from the root crown not individual canes. Topping the canes won't make a single stem get fuller and kind of wrecks the intended form. Leave the main stem alone. It is blooming. Why would you want to chop that off?

You want the fatsia to be the taller shrub in this grouping. Remove the lower leaves from the main trunk and let the ferns be the groundcover below.

A lot of how to maintain this plant is going to depend on your climate and if it can get frozen in the winter.

Fatsias as outdoor specimens are common in my area. They are an excellent choice for dry shade although tolerant of a range of other growing conditions. They are also very tolerant of hard pruning should the plant outgrow its space, so they can be taken back virtually to ground level and will regenerate rapidly. Winter dieback/damage is common here in exposed areas and with an Arctic blast and this is a common late spring activity to cut back the fatsia hard to remove all damaged portions. The plant is generally back in full flush by the end of the growing season.

It would seem much easier to move the surrounding plants and leave it be. I think it is lovely. This coming from someone who tries very hard to avoid zone envy.

Fatsia japonica is also common here. If you think it is getting too big it is happy to be cut back hard and yours is certainly not too young to be pruned. If you want it to be bushier pruning it this spring would be a good move. I think Christopher might be thinking of Fatshedera rather than Fatsia. The latter is most definitely a shrub/small tree and will branch out from lopped off trunks.

I think of the Fatsia along the same line as Rice Paper Plant, Tetrapanax papyriferum or like many Aralia to which the Fatsia formerly belonged. Proper pruning would be the removal of old canes at the bottom, not lopping them off halfway up the cane and hoping they branch out.

Yes, it is a woody shrub and a large one at that, more so if they don't freeze to the ground in the winter. That is what it should be allowed to be to show its best form. This one has not even reached fence height yet. This one needs to be the large shrub in this setting. You want it taller, not shorter and bushier. Don't cut off the top of the one cane you have. Limb it up like a tree.

‘hoping they branch out.’. You don’t need to hope. It will. If the OP’s were headed back it would branch out rather than growing straight up as a single trunk. It all depends what form they want. These things are planted all around here in local parks where they grow on single or a few trunks and get pruned back regularly with no ill effects. They are rarely killed back by frost but the tips occasionally brown off.

Btw, jhalt, yours is by no means ’very large’. It can easily grow to 12 - 15 feet and will overtop your fence. But if you really want it smaller and bushier, go ahead and lop it off. It will be fine.

im with peren... ID ALL THE OTHER STUFF .. and then decide what the priority is for the spot ...

e.g. .... i sure wouldnt prune a magnificent specimen.. to allow a common fern below to show.. move the fern ...

once you know al the plants.. then apply gals advice since its a common plants for her area .. btw.. where are you.. big city name ... it will tell us how aggressive it will be ..

ken

Fatsia japonica will not be fussy how it's pruned. Shape it the way you would like.