It's likely there was some issue with the roots on that side of the tree. Perhaps that side of the pot or container faced the south and the roots got too hot, or it may have been a watering issue.

It's hard to offer guidance w/o seeing your tree (a picture). You can promote back-budding by letting the tree grow wild until it is in excellent health and has lots of energy reserves, and then cutting it back hard. Occasionally, as the tree gains strength, it will back-bud on older wood on it's own, but you never know where the new buds might occur. How old your tree is, is a factor as well. Trees that are a high % of dynamic mass back-bud readily, but older trees get more reluctant to back-bud on older wood as the bark thickens.

There is also the thought that perhaps, after the radical change, a different way of styling the tree so the lost branches become a non-issue might be optional. Tilt the tree this way and that, and see if you can't look into the future and develop a different vision for what you initially had in mind for your tree - the old "When life gives you lemons ..... make lemonade" thing.

You don't say where you live, or give many details about your tree's care, but a good soil, light, and proper nutritional supplementation are key issues if you are to keep your tree in good health. If you want to start a more in depth discussion, that's ok, but the info so far is too sketchy to help you much.

How long have you had your tree?

Al

Sorry for not providing much information. My tree is quite young; around 4 years. I obtained my tree September 2010 when I began training it. I also did decide to let it grow wild for a while after the branches died. My bonsai sits on an East facing window, and I live in Minnesota, meaning during this season the plant is getting at least 9 hours of sunlight a day. I water at least once every 2 - 3 days, but usually aim for once a day. I got the soil and tree from a bonsai society in this state.

Thanks for your help! :)

Some things to consider:

If it's on an east windowsill, (it's almost a given) it's not getting enough light, and it might be too cold there for the plant. (Your user info doesn't tell us where you live - you might wish to fix that. It makes it easier for others to help.) Soil temps should be above 60* always. They will tolerate lower soil temps for a while, but they prefer soil temps in the 65-75* range. If you're trying to water once each day, it's very likely that you're over-watering. In most cases I've seen, the bonsai soil sold at bonsai shops & even by bonsai clubs is finer than ideal. The reason is two-fold. They are trying to make a profit, so screening the fines out of the material is both an extra step (time is money) and they would lose a considerable fraction of the products they are using to make the soil (which they had to pay for) if they screened out the inappropriately-sized particles. I didn't say that to disparage the soils, I said it to impress upon you that you need to be very careful about how you water bonsai. Because of the shallow pots, ANY perched water table (PWT) is a large fraction of the soil, and PWTs kill roots.

E.g., if you are growing in a pot that is 3" deep, and in a soil that supports a 1 - 1-1/2" PWT. 1/3 to 1/2 of your soil remains saturated after you water. This is decidedly bad for your roots, and may be why your tree is suffering.

Water AS NEEDED. Use a sharp dowel & stick it in the soil all the way to the bottom of the pot. Don't water until it comes out clean and dry. After you water, tilt the pot steeply toward a drain hole - it will cause MUCH more water to drain from the soil. Try it. Water, making sure you flush the soil, & wait for the pot to stop draining. Then, tip the pot so a drain hole is down, and watch how much more water exits the pot. Also, use a wick to help with drainage - you can also use the wick as a 'tell', to let you know when it's time to water. You can read more about tips on how to deal with excess water retention by following the embedded link.

Have you been flushing the soil regularly? Where do you live? Are you fertilizing - with what - what strength?

Al

Hm... What window direction would you recommend? The temperature where the bonsai sits is always around 65 degrees, and I do have a heater there incase the temperature needs to be raised.

Thank you for the watering tips. I'll definitely change my watering habits.

I have not been flushing regularly... How does one properly go about flushing the soil? I live in Minnesota in the U.S., and I'm not fertilizing, even though I probably should be..

Each time you water, the soil should be fully saturated and at least 10-15% of the total volume of water you apply should exit the drain holes. This flushes accumulating salts from the soil. In winter, you should also be fertilizing at low doses, but only if you are watering in the manner I described. If you water in small sips, the accumulating salts from your tap water makes it increasingly difficult for the plant to take up water and the nutrients dissolved in water.

I prefer fertilizers in the 3:1:2 ratio. Examples commonly found are MG or Peter's 24-8-16, MG 12-4-8, or my favorite - Foliage-Pro 9-3-6. I prefer the Foliage-Pro because it also supplies Ca and Mg, two elements commonly missing from soluble fertilizers. It also supplies nutrients in almost exactly the same ratio in which plants use them (allows you to keep soluble salts levels at the lowest possible w/o nutritional deficiencies) and in a favorable ratio to each other.

The plant would prefer a south window. I'm not sure what kind of heater you have, but make sure the warm air isn't blowing directly on the plant.

Make sure you read the link I left upthread.

For a more thorough understanding of how water behaves in soils (imperative if you are going to progress in the discipline of bonsai), get an understanding of what's in the link below under your belt.

Al

Here is a link that might be useful: More about soils

Oh, in that case I do indeed flush the soil every time I water the bonsai. I guess I was just confused by the term flushing.

Thank you for the fertilizer advice. I will certainly look into that more.

The problem about my home is that the there are only East and West facing windows... Do you think it'll survive in the East? And the heater I have is quite gentle and is certainly not directly blowing on the bonsai.

I did indeed read that link you left, and it was quite informative. I'll definitely read the one about soils as well.

Don't underestimate the effect of adequate humidity.

The Golden Gate Ficus has leaves high in cuticular wax & tolerates low humidity well, though that's not to say humidity of over about 40% isn't a plus. I keep the humidity in the room where I keep my Ficus at 50% or a little higher.

If you have issues with necrotic leaf tips and margins (spoiled foliage), look first to the level of soluble salts in the soil (solution), THEN to humidity as a contributor to the problem, rather than looking to low humidity as the direct cause.

Al