Living through a harsher than normal winter gives us an appreciation for green life. Bringing houseplants into your home or office can offer some natural calm and tranquility. But for those of us with a history of throwing out dead plants, it may seem like we should stay away from house plants. Not so, we say! Here are some simple tips for keeping your indoor garden green and lush.
Plants grown inside the home obviously need the same things as plants growing in your garden: water, light, soil, nutrients, etc. When you grow houseplants, you’ll need to provide them with the proper environment, and carefully monitor your plants to make sure they continue to grow in healthy conditions.
When you buy your houseplants, inspect them carefully to make sure they should now signs of diseases. Also look for evidence of pests both on the top and bottoms of the leaves. For more on pests, click here.
Soils and Pots for Houseplants
If you receive a houseplant as a gift or buy one directly from the nursery, it will probably not need a new pot or new soil for quite a while.
In general, some houseplants need to be repotted once every two years, while others may need a new pot or new soil more frequently. Usually it is time to repot a houseplant when it becomes root bound. This means that the roots begin to fill up the pot and no longer have sufficient room. The roots in this case may begin to grow in dense clumps, displacing the soil. You’ll notice when a plant becomes root bound when the water drains out of the bottom quickly, the plant constantly needs water, or there is limited new, healthy growth.
As a general rule, it’s recommendable to repot when the plant is actively growing. Spring, summer, and early fall are good times. When you repot, you’ll need to carefully select a soil mixture appropriate for growing houseplants. Look for a “peat-lite” mix with a high content of sphagnum peat. The potting soil should also contain equal parts vermiculite and perlite.
It’s a good idea to remove old soil when you replant. Gently pull up the root ball and shake off the soil. Next, add new soil to the bottom of the new container and place the plant into the pot. Add more new soil around the root ball. Do not pack the soil too much. Keep the root ball slightly below the level of the soil, but do not fill the container to the rim with soil.
Note that cacti and some succulents require higher levels of sand. Mix equal amounts of your potting soil with sand when growing cactus. Avoid using sand from your neighborhood dirt lot. Instead, buy sterilized sand used specifically for growing plants. Likewise, don’t add garden soil to your potting mix. Your houseplants will grow better in soil specifically designed for them.
When you grow unusual houseplants like epiphytes and orchids, you’ll need a special soil medium to grow them. Orchid bark is a good soil mix to use in this case. Also, make sure to ask your nursery or extension agent about the soil needs of specific kinds of houseplants. For example, gardenias like acidic soils. The addition of peat moss to your potting mix will help gardenias thrive. Consider using an electronic soil tester to determine the quality and acidity of your soil.
When making a soil mixture for repotting your plants, make sure you use sterilized soil. This will minimize potential problems with soil borne diseases and pests. There are also several techniques you can use to sterilize soil if you have an old batch of potting soil you’d like to recycle. See this website from Colorado State University for more information on sterilizing potting soil.
A good container is also important for growing houseplants. When you select a container, pick a pot that isn’t dramatically larger than the original one. This will allow your plant to feel comfortable in its new space, and will ensure that your plant’s roots will absorb water from the soil properly. Take into account that clay containers absorb some of the moisture from the soil and make it dry out a little faster. Always pick containers that have a sufficient number of holes in the bottom to drain water. Check the holes occasionally to make sure they aren’t plugged. Plants like ferns often love hanging planter baskets.
Fertilizers for Houseplants
Houseplants need plenty of organic nutrients to grow properly. If you use high quality potting soil and add well decomposed compost to your soil, your plants should receive most of the nutrients they need. You may also choose to occasionally give your houseplants a dose of fertilizer to help them grow.
When fertilizing houseplants, we recommend that you try out compost teas or other natural fertilizers before using potentially harmful chemical fertilizers. Slow release fertilizers are a good pick for use on houseplants. Many organic fertilizers are slow release and will help to minimize the risk of “burning” your plants. Garrett Juice is an excellent organic fertilizer that you can purchase ready made or you can make yourself.
Whether you choose to use chemical or organic fertilizers, always make sure you read the instructions carefully. Over applying fertilizers can be harmful to your plants and to the environment. Also, if you overuse fertilizers, your plant may actually become weaker.
Spring and summer are good times to fertilize houseplants. It’s best not to fertilize houseplants during the winter when they are dormant. If you notice that your plant does not look healthy, do not add fertilizer as a way to stimulate growth. Check for other issues like lack of light, root bound pots, diseases, and pests. See this troubleshooting guide for more tips.
Note that plants that are grown in full sun will generally need more frequent treatments with fertilizers.
Watering is one of the most important factors for growing houseplants successfully, so read this section carefully! Consistent and proper watering will keep your plants happy and healthy.
If you over water your plants, they may suffer from disease, root rot, etc. Your plants will also be stressed and unhealthy if you underwater. Additionally, if you let the soil dry out too much and too often, it may have trouble absorbing water in the long run. Remember to never let your plants get so dry that they begin to wilt. This will cause them severe stress and will make your houseplants more susceptible to disease and pests.
Note that different kinds of houseplants have different watering schedules. You can check our list of recommended houseplants to get an idea how often to water your plants. If your plant is not on the list, make sure to do some research to find out how often you need to water it.
As a general rule, houseplants with flowers need watering more frequently than plants that only have foliage. To test if your houseplants need water, you can use a soil tester or feel the soil with your finger. When you use your finger, if the first 1 ½ inches of soil are moist, you can wait a little while longer to water.
Pay attention when you water your plants. The water should gradually soak into the soil. If the water drains out quickly, your plant may be root bound. Water your plants thoroughly. It’s ok to let a little water drain out of the bottom of your pots. However, don’t let your plants sit in water for extended periods of time. Discard any extra water.
When you water indoor plants, a good method is to use a watering can. In the summer, another option is to take your houseplants outside and use a hose with an attachment to gently apply water to the plants.
Some people also like to water their houseplants by placing them in a container of water. Choose a large bucket or similar container and place the houseplant inside. Gradually fill the bucket until the water is over half way above the top of the pot. Do not let the water get above the rim of the pot. Let the plant soak for a while and remove it when the top layer of soil feels wet. If you use this technique, occasionally water your plants with a watering can. This will help pull accumulated salts out of the soil.
If you need to travel or be away from your plants for awhile, don’t worry. In these cases there are a number of handy houseplant watering devices available to help slowly water your plants while you’re gone.
Humidity and Temperature
Some houseplants, especially ones originally from tropical climates, prefer humid environments. During the winter, your home may become very dry due to your heating system. Some houseplants are sensitive to these dry conditions and may need a little help.
Try using a humidifier to balance out humidity levels in a dry climate. You can also use a mister to moisture the leaves occasionally. Also, if you have a special room in your home where you can control the humidity, it’s a good idea to keep your most sensitive plants there. Note that many orchids have special needs and like high levels of moisture. Read this excellent guide to growing orchids for more information.
As far are temperature goes, as a general rule flowering plants prefer cooler spots, especially at night. This will extend the life of the flowers. Around 60 to 70 degrees average daytime temperatures are good for flowering plants. Low temperatures of 60 degrees are recommended at night.
Plants without flowers generally do well in slighter higher temperatures. Make sure to read up on the recommended maximum and minimum temperatures for your foliage houseplants. Our list of recommended houseplants discusses plants that can handle lower temperatures. Also, this website from the University of Missouri (PDF file) has a list of common houseplants and their temperature requirements.
No matter what kind of houseplants you grow, avoid placing them near drafty windows in the winter. Also, avoid placing houseplants near heaters or radiators during this time. The sharp temperature changes can stress and weaken the plants.
Light Levels for Houseplants
Giving your houseplants the proper amount of lighting involves first selecting appropriate places to grow them. If you’ve carefully observed your house and thought about where you’d like to grow plants, you’ll have good idea where you can grow houseplants. You can also consider building or buying small planters or other structures such as window boxes to help your plants get closer to windows.
South and west facing windows typically get high levels of light. Obviously, the larger the window is, the more light. The intense light in some locations may be unhealthy for some plants, especially when they are flowering. Flowers will last longer when the light is indirect.
Fluorescent lights and grow lights are good options to provide extra, low-intensity level light to your plants. You’ll need to locate your plants fairly close to these artificial light sources, about 16” from the top of the plant. About 14 hours of artificial light will work for most houseplants.
Plants that are mostly foliage vary widely in how much light they need. Read up carefully on what your foliage plants require. If they need full sun, a south facing window is best. Once your plants are established and growing in their spot, don’t move them to an area with different light levels. If you need to move a plant, move them to a spot with intermediate light levels first.
Plants may start to grow towards a light source. To grow a more even plant, rotate the container occasionally.
Other Houseplant Growing Tips
Some houseplants benefit from some time outdoors during the summer. Wait until temperatures are warm enough to place the plants outside. Make sure night time temperatures don’t get below the recommended low temperatures. You may want to gradually expose the plants to outside temperatures by moving them outdoors a few hours a day and moving them back indoors at night.
Keep track of light levels as well. Plants moved outdoors may receive a lot more light than they do indoors. Try placing them in an area of filtered light for a couple weeks before moving them to an area with strong, direct light.
Heavy rains and winds may damage some houseplants. Ask your nursery or extension agent if you’re unsure weather or not a plant is ok to set outside during the summer.
Keep in mind that if you keep your houseplants outdoors for part of the year they will dry out more quickly. During the summer you can choose to place your houseplants with the entire container inserted into garden soil. This will cool the pot and maintain moisture levels. However, there is a slight risk that the roots will grow into the soil, so make sure to remove the plants periodically and check the bottom.
Also, check your plants for pests and diseases if they’ve spent part of the year outdoors.
For more on growing green plants, go to HouseplantGrowing.com