I have 2 Maples in large pots, about 2ft diameter pots. The Maples seem like they are starting to outgrow the pots. Should I find bigger pots, or plant them in the ground, or will I be ok?
Where are you?
Ohio? Antarctica? Brazil?
The more information you provide the more likely you are to get a helpful reply.
Zone 8 in central Texas.
Also need to know the variety of JM and how long they have been in those containers. Anything grown in a container long term will need to be unpotted, root pruned and repotted with fresh medium from time to time. Now is not a great time to do so however, especially in Texas - wait until fall.
I have no idea what kind of Japanese Maples they are. One is a dwarf maple with green leaves, and the other is tall with red leaves. The dwarf one looks healthy, but the tall one doesn't bloom much compared to the dwarf.
So I should be fine and keep them in the container as long as I prune the roots? I didn't know people pruned roots until now. Thanks.
You'll find a lot more information specific to maintaining trees in containers over the long term if you click on the link.
Why not add something to your user info that tells us something about where you live, like Pam's 'PNW zone 8' or my 'z5b-6a mid-MI'?
Here is a link that might be useful: More about trees in containers if yiou click me ...
Just Zone info usually is not enough information for good advice. My Zone 8 near Seattle has a lot different climate than Zone 8 in Texas. We just share the same winter lows is all. Strength of sun, moisture, soil, and humidity are way different. That's why it's always nice to give a general location of where you are in addition to your Zone.
I'd put em' in the ground. It's a lot less work maintaining them.
I have three, six foot Japanese maples growing in pots on my balcony. The leaves are turning light brown on the edges and falling off, so I feel the trees may need more frequent deep watering. I usually give them a deep soaking once a week. How much more frequently should I water them. Also, they have been potted for four years? When and how should I re-pot them?
I'm pretty new to this (so I've been devouring online videos) and I saw that JM's can get sort of sunburned if they get too much sun. It could totally just be a water issue, but I heard of this product called "wilt stop" that's a waxed based spray that acts like sunscreen for leaves. No idea of it's a good idea or not, but I'd look into it. Could be they are just getting too much direct sun.
Don't spray anything other than water on JM foliage! It is very delicate tissue and can easily be damaged by applied sprays. It is even cautioned not to apply fungicides or pesticidal sprays due to phytotoxicity.
JM's of some varieties can experience scorch if in too much sun but your description does sound like a tree that needs to be repotted. Depending on the size of the container, the roots could have completely filled the area, the potting medium has broken down and any water just passes quickly through the root ball and so is unable to fully hydrate the root system when you do water. Until you are able to repot, you may need to provide water more often.
The ideal time for repotting is when the trees are dormant - fall in mild winter areas or late winter/early spring in colder areas. You will most likely need to do some root pruning as well as provide fresh potting soil. Check out the link Al provided - it really does outline everything you need to know about growing JM's (and other trees) in pots.