For one thing, sun, lots of sun. Water well, but let soil dry between waterings. They love being summered outdoors.
Fertilize when you see new growth, using an All Purpose fertilizer. Once a month, during growing season is sufficient. Follow container directions..but half recommeded dosage is best. Ficus, Rubber Trees, are not the fastest growing plants, so over-fertilizing will cause spindly growth and ill-health.
Well-draining soil is important. Heavy soils remain wet for long periods..which means, root rot and insects. My two Rubber Trees are potted in an All Purpose soil, with added Perlite.
Wash and/or hose leaves regularly to keep foliage clean. Don't use leaf shine, that stuff is a nightmare.

What color and size is your Rubber Tree? If variegated, it should get more light than green w/red edge, but they all need a good amount of light. Toni

You'll find quite a bit of information aimed specifically at maintaining Ficus trees in containers at the link below.

I hope you find it helpful.

Al

Here is a link that might be useful: More about maintaining Ficus trees in containers

wow someone here told me that sun turns the leaves brown on a rubber plant.I know my ficus trees love the sun, but I thought rubber trees were different. Rubber tree is no longer in the sun but the leaves still seem to be turning brown.

It's probably not a light issue. Odds favor your problem is something soil-related - probably over-watering and/or a build-up of soluble salts in the soil, but you would need to provide a lot more information to determine what is actually wrong so 'how to fix it' can be determined.

The link I provided above will go a long way toward defining exactly how to keep your tree healthy.

Al

Cyn, when you say its leaves are turning brown, what do you mean?
Is the brown crispy or soft?
There are many reasons leaves brown.

If an F.'Rubber Tree' is placed in full/bright sun, the leaves will darken.
Especially variegated or burgandy trees. The object of full sun is to keep colors vivid, more pronounced.
When a Ficus isn't getting enough light, colors fade. Toni

Thanks for your response. I guess they would be considered soft. The plant had these spots o some leaves when I bought it. I cut those leaves off but now it has more.

Cyn, you stated: "Rubber tree is no longer in the sun but the leaves still seem to be turning brown."

How long was it in the sun before you moved it? Are you letting it dry out between waterings. Can you post a photo?

Jane

Please do a Google IMAGE search using the words Ficus elastica oedema and compare your symptoms with some of the pictures to see if they match up. There's not really much to go on yet in the way of clues, but if the spots do match up and you find they are related to oedema, the cause is almost certainly over-watering. The spots would first have been wet lesions that you may or may not notice, turning brown & corky as the plant tries to 'seal' the injury.

There are other possible causes, but I doubt they are light related. Photo-oxidation (sunburn) usually turns rather large patches of tissue silver before it turns brown, but usually the 'sunburned' areas will be quite large, perhaps palm-size or larger; and 'spots' aren't symptomatic of a light deficiency.

If it's not oedema, and you can't provide a picture, an accurate description of the spots, including if there is a red/purple or yellow halo around them, would be helpful.

Al