Gardening indoors includes houseplants and plants that are just indoors for the winter.The heat and light indoors calls for special care of your houseplants and over wintering of tender garden plants. There are other problems which need consideration including salt build-up, humidity, drafts, pests, how you water your plants and what to do if they get pot bound.

The best thing you can do for your indoor plants is to learn something about the growing conditions your particular plants like and provide as close to those conditions as possible.If you see a problem developing, take action quickly.

Houseplant Problems

Becoming Pot Bound

Sooner or later a healthy, growing houseplant is going to out grow its pot. When a plant gets too large for its pot, the roots circle around inside the pot and start to restrict themselves. If your plants seem to dry out more quickly than they used to, but are otherwise healthy, they are probably pot bound. There are simply too many roots in the pot and not enough soil is left to hold and distribute water. Re-pot your houseplant into a pot an inch or two larger. Don't try to go too large, as too much soil means the roots will be sitting in damp conditions and the roots will begin to rot.

Pests

Indoor pests multiply quickly. There are no natural predators to keep them in check, so checking frequently for symptoms. Spider mites, aphids, mealy bugs and scale can cover a plant in days. If severe enough, the plant may never recover. Keep an eye out for leaves that become discoloured or curled and for plants that look limp even when they're watered. Learn to spot the following common houseplant pests.

Spider Mites leave telltale webbing, especially on the inner joints of plants and in plants with lush foliage. The tiny mites are about the size of a pinhead and attack plants by sucking their juices. Leaves will have yellow stippling. As the infestation gets worse, the leaves will turn totally yellow and brittle and die. To get rid of spider mites, spray the affected plants with insecticidal soap.

Mealy Bugs are small cottony white blobs, usually attached to the plant at the stem joints, but they may also be found along the stems. They feed off the plants by sucking. Plants infested with mealy bugs often look like they are drying out, even when they've been watered. Mealy bugs are very hard to get rid of. If you catch the problem early, cut out the infested branches. If your plants become severely infested, it would be best to just get rid of them.

Scales are small insects that attach themselves to the stem of a plant and cover themselves with a hard, oval shaped shell. Like mealy bugs, they slowly suck the sap from plants, leaving them weak. They are very hard to get rid of so it is probably best to replace the plant.

Aphids look like small green, white, yellow or black spots that can surface on all parts of a plant. Aphids can reproduce so quickly that an infestation will cover the plant in days. They are soft bodied insects and can be killed quite easily by a strong blast of water or repeated sprays of insecticidal soap. But they are persistent so you will need to keep an eye on these plants and treat regularly.

Heat

Many gardeners think they are doing their houseplants a favour by placing them in a warm spot, but placing your indoor plants near a direct source of heat, like a radiator, will dehydrate the plant very quickly. Even if you are careful about watering the soil, the foliage will quickly become dehydrated.

Drafts

Placing an indoor plant, especially a tropical or blooming plant, near a frequently opened door to the outside or too close to a window with limited insulation will have the same effect as leaving the plant unprotected outside. You will probably first notice leaves dropping and the plant may look like it needs water, when actually it needs warmth.

Light

Plants that are not getting as much light as they need will look pale, rather than a healthy green and new growth is spindly, as it reaches for the sun. You may also notice that the new leaves are smaller than usual. However, most houseplants don't like to be placed in the direct sun of a windowsill. Strong sunlight may actually burn their leaves. Only plants that specify bright, direct sun, like Cyclamen, gardenia, geranium and other indoor plants grown for their flowers, should be sited in a south facing window. Low light plants, like Philodendron, will be fine placed further in a room where indirect sunlight reaches. Those in between are the houseplants you'll need to keep watch on. East and west facing windows are fine for most plants, but if your home lets in a lot of light, you may be able to grow houseplants well away from the windows.

Humidity

Lack of humidity can kill indoor plants. You may first notice this as browning leaf tips before the leaves die and drop. If your house tends to be dry, you can increase humidity around your houseplants by placing a tray of pebbles under the pots, filling the tray to just below the pot's bottom. Do not let your plants sit directly in the water. You can also provide some humidity by misting your plants each day. If you have lots of houseplants, you may want to invest in a humidifier.

Salt Build-up

Water your potted plants with enough water so the soil gets wet and is allowed to drain through. Not watering enough can lead to salt build-up which can inhibit growth. You may not notice it until you start to see whitish crust on the soil or sides of the pot. At least once a month, water your potted plants thoroughly, so that excess salts will be flushed out the drainage hole of the pot.

Watering

The number one killer of houseplants is over watering, which leads to root rot. Plants take in air through their roots and if the soil is constantly wet, they can't do this. Instead you'll be encouraging root rot, which can kill a houseplant. Don't let your plants sit in water and don't automatically water all your houseplants on a schedule. Check to see if the soil about 1" below the surface is dry, before you water. When you do water, water thoroughly. Water until you see the water coming out the bottom drainage holes. It will also help if you use a light potting soil instead of garden soil, which tends to be heavy and doesn't allow water to drain through.

Over-wintering Tender Plants

Outdoor plants can be brought indoors as houseplants for the winter. However there are some points to remember:

Keep only healthy plants

If something has been struggling all summer under the best of conditions, it is not going to improve indoors.

Never bring in a plant with pests or disease

Problems spread more quickly among indoor plants than in the garden.

If the plant looks good as a house plant, bring it in and use it as one

Many people have the light to successfully winter geraniums and begonias in full bloom.