Proper watering of your indoor plants is as important as proper lighting. More indoor plants are killed by over-watering than by any other cause, so it is important to know the water requirements of each plant that you have indoors. It is also important to note that plants that are grown indoors in containers will require more frequent watering than plants grown outside in the ground because the containers restrict the growth of the root system. Electric lighting also creates a drying effect that creates a need for more frequent watering.
Indoor plants can be watered with regular tap water. The chlorine and fluoride that is added to most city water will not harm your house plants. However, do not water your plants with water that has been run through a water softener, especially a water softener that uses salt. If you do buy bottled water for your plants, buy regular spring water or drinking water, not distilled water. Distilled water has had all the minerals removed and your plants do need the minerals that are naturally found in drinking water. Use water that is the same temperature as the room the plant is in. Using water that is too cold or too hot can shock your plant’s root system.
The humidity in the room is also an important factor to consider in your plant’s water needs. If the room air is very dry, consider using a humidifier. Air that is too dry for too long can cause the leaves of the plant to dry and curl at the edges. You can also mist the plants leaves, depending on the plant, if the air in the room is too dry. Mist the leaves early in the day to prevent them from rotting overnight.
Not all plants have the same water requirements. Tropical plants may require more water than Mediterranean plants and flowering plants will require more water than plants that do not flower. Carefully read the watering instructions for all the plants or seeds that you purchase.
Along these same lines, not all of your plants will need watering at the same time. The size of each plant, the amount of light and ventilation each plant gets, the temperature and humidity of the room all have an effect on how much water a plant needs. Watering all of your indoor plants at the same time each week is not a good practice. Instead, learn to tell when your plants need water by the feel and color of the soil. As the soil dries out it will become a lighter color and will eventually begin to pull away from the sides of the container and even crack. A good way to check the moisture content of the soil is to stick your finger into the soil one or two inches deep. If the soil at the bottom of the hole is dry, your plant needs water.
Do not water your plants until the soil is dry enough that the plant actually needs water. When the soil is too wet the plant can not get enough oxygen and will literally drown. The roots will turn brown and will rot or will be subject to disease and the leaves will turn yellow and will fall off.
While it is better to let a plant get a little too dry than to over–water it, letting a plant stay too dry can also kill the roots. If you are away from home often or find it difficult to gauge when your plants need water, you can invest in self-watering planters that will constantly give your plants the proper amount of water.
Do not water your indoor plants at night. Transpiration, the process where water vapor passes through the leaves of the plant, is an important part of the watering process and can not occur at night in indoor plants.
Do not automatically assume that the plant needs watering if it appears stressed. Carefully check the soil’s moisture by sticking your finger as far down into the dirt as possible before you water a plant that appears stressed.
There are two methods you can use to water your plants. One method is to water your plants from the top of the soil. When watering from the top of the soil, use a watering can with a narrow spout that will fit between the leaves to prevent splashing too much water on the foliage. Water all over the top of the soil, not just in the middle on or the sides.
You can also water your plants from the bottom. For some plants that do not tolerate moisture on their leaves, such as African violets, this is the best method. This method is also preferred for most plants because it allows the water to soak up through the entire soil base. Many plant containers have large saucers that go underneath the pot. Fill this saucer with water and allow the soil to soak up the water through the drainage holes. Allow the water to stand for one hour and then drain off any remaining water. Do not allow the remaining water to stay in the saucer. This will result in over-watering and prevent the roots from receiving the oxygen they need.
If you container does not have a saucer, fill a sink or large bucket partially with water and place the plant container in the sink or bucket. Make sure that the water does not flow over the top of the container. Let the plant sit in the water until the top of the soil is moist.
Plants that are consistently watered from the bottom may eventually show signs of salt build-up on the top of the soil. If this salt build-up is moderate, water the plant from the top of the soil thoroughly and discard the water that drains out of the soil. If the salt build-up is heavy, scrape off the top layer of the soil, taking care not to disturb the roots, and replace it with fresh soil.