GardenSmart :: EPISODES :: 2003 show34
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Show #34

Typically we discuss outdoor plants on THE SOUTHERN GARDENER, today, however we'll cover indoor house plants.

The average life expectancy of an indoor plant is 6 months. This means half of those plants don't even live that long. The roles of light and water are reversed in this situation. Plants growing outside in a nursery have plenty of light, so to them the limiting factor is water and nutrients. In an indoor situation there is often a lack of light, often too much water. There are hundreds of potential indoor plants from which to choose, the key is finding plants that will tolerate light levels available inside your home. It is usual to have too much water and too little light. There are 100 to 150 indoor plants from which to choose. The key is finding plants that can tolerate the light in your home. First you must determine how much light is in your home. Light is measured in foot candles. If you don't have a foot-candle meter you can look at different elements to measure light. For example, if you have a north facing window in your home, that is considered bright, indirect light and that is about 100 foot-candles. An average indoor light, fluorescent or incandescent, is about 50 foot-candles. Lower light levels where one can barely read is around 25 to 30 foot-candles. Anything below that is very low light and most plants can't survive.

When we bring our plants inside, we tend to repot into larger containers. By doing this, putting the plant in more soil, we change the root-to-soil ratio and this can devastate indoor plants. In an outdoor setting it is a good idea to surround the plant with a lot of soil because the roots don't dry out as fast. In an indoor setting it is better that they dry out faster. A better approach, if you want a bigger pot, is to try pot-in-pot. We leave the plant in its' original container and place the old pot in a larger, more decorative container. Typically the larger container won't have holes in the bottom so water won't leak onto the rug or floor. To do this we fill the larger container with styrofoam peanuts or a little bark, this allows the original container to sit up in the new pot. Make sure it is about half an inch from the top of the new container. Dr. Rick has another tip in this situation. Place a short piece of 3/4" PVC pipe through the mulch all the way to the bottom of the container. You can then put a stick, a piece of bamboo or paper support from a coat hanger down the pipe. This allows you to check for excess water at the bottom of the container. Place the pipe at the edge of the container and bring it to the top of the container. This acts like a dipstick in your car and helps you monitor liquid in your containers and is an effective way to keep the roots of indoor house plants reasonably dry.

If you are intent on repotting into a larger pot, Dr. Rick has several ideas to aid your success. First, use clay rather than plastic pots. Clay breathes and allows moisture to move through and evaporate keeping the roots dryer. Another tip, use a premium potting soil. The best potting soils have perlite, they are the little white pieces in potting soil. These add air to the mix and it aids in drying out the soil. Make sure the potting soil is a light mix, since heavy mixes hold water. So clay, a mix with Perlite will help in not over watering your plants.

It is important to know how much water each individual plant needs and several other characteristics. Trees are easy to identify, they have leaves, often a trunk and they look like a tree. Benjamin Fig or Weeping Fig are difficult to grow. They are popular because they grow fast and put on a lot of size in a nursery. It is not unusual for them to grow a foot or more in a couple of months in a nursery. But Dr. Rick doesn't think they are good houseplants. They have thin leaves and their roots are fibrous. Fibrous means they have lots of tiny roots. Both of these factors mean the plant isn't able to store water. If it stays too dry or gets too wet the plant suffers, if it is near a cool or hot draft they tend to drop their leaves. Ming Aralia also has thin leaves and a fibrous root system. Both of these plants need very bright, high light. If you have a north facing window they may do reasonably well, but expect a lot of leaf drop off. Schefflera isn't as difficult to grow. They grow fast in the nursery, thus are popular and inexpensive. They tolerate lower light levels because it has a thicker leaf it can hold water better.

Another group to consider is the Palms. They have a very tropical, airy look. Someone said they look like they are always reaching, never getting there. They are similar to Trees in that they have thin leaves and can't store much water. Their roots do store a lot of water thus are easier to grow. Palms require a great deal of light. Areca Palm is a challenge to grow because it needs high light. The Raphis Palm is smaller, has thin leaves but thicker roots allowing it to store a lot of moisture. Raphis Palm doesn't need as much light and tends to do better in indoor situations. Unlike Trees when Palms are over watered they don't drop leaves. They do tell you about their water situation though. If the tip of the leaf has turned brown it means the plant is staying too dry. If the entire leaf turns yellow then it is going into a drought situation. If the plant is being over watered there will be yellow at the tips of the leaves.

Canes are a tough group of plants. Dracaenas are durable because they have leathery type foliage, that stores a lot of water, and they have a root system that holds water. Both qualities that make them, great indoor houseplants. They grow slowly which is a key ingredient to a good houseplant. If it is fast growing its' metabolism is quick and changes in the environment have a dramatic effect. Too much water, too little water can really effect it. Slow growing plants on the other hand do well because they aren't effected by changes. Canes do well in indoor situations, they can tolerate 25 foot-candles of light. Let them dry down to about 3/4 to 4/5 of the way in the pot. One way to measure this is to pick up the pot and see if it is heavy or light. Do not over water, the leaves will yellow, losing the lower leaves until 2 or 3 remain at the top. Let them dry down, water every 2 weeks or so. Dracaena Tricolor, also known as Dragon Tree has color on the outside of the leaves and is a spiky, upright plant. Song of Jamaica is a Pleomele, another great Dracaena. Both are good indoor plants, especially if you need height with low maintenance.

Vines are good plants that don't require much care. Ivies are a great example. They tolerate low light, down to 25 foot candles. They don't produce a lot of wood to support themselves, particularly varieties that crawl or grow across the ground. Therefore they don't use energy building themselves allowing them to be more durable and tougher than a lot of plants. When looking for a vine check to see if they're under rooted. Pull the plant out of the container and look at the amount of roots, make sure there are plenty. Also look at the stems and check to see if there are several vines coming off each stem. Otherwise they will tend to look scraggly on the top of the plant. One of Dr. Rick's favorites is Pothos. Marble Queen Pothos is best grown not cascading down, but supported on a bench or on a totem. A totem is a piece of wood, placed in the pot which allows the vine to grow up the piece of wood. Their roots will attach to the wood and it allows vertical height. When they hang down, it puts pressure on the vine and they tend to loose leaves at the top.

Lilies are another of Dr. Ricks' favorites. Spathiphyllum or Peace Lily tolerates very low light levels and produces a spath or flower giving it added interest and is a little fragrant. It is pretty much a leaf with a long Petiole so there is no wood and no trunk to use a lot of energy. It has a very good water holding root system. Aglaonema, White Lance, will tell you when it needs watered. They start to wilt, the leaves turn a bit pale, then the leaves start to fall, when that happens it is time to water. The root system on these plants and most indoor plants is like a pump that's switched on all the time. If there is water in the container it will continue to pump water into the leaves. When that happens, they tend to yellow around the edge. It is best to let house plants dry down to temporary wilt, let the leaves turn pale and start to wilt.

Cacti is one of the easiest group of plants to care for and they grow slowly. In fact the size of the plant when purchased is probably going to be the ultimate size. They have a thick, waxy coating to keep them from transpiring. They come from native areas where extreme drought is common as a result they require very little water. If over watered they will rot from the inside, often times it is difficult to determine if they are dead. One indicator is the plant becomes loose in the pot, this indicates the roots are rotting. A couple of teaspoons of water per month is all they need. Don't over fertilize them, that too rots the roots. Golden Barrel is in the shape of a barrel. It requires extremely low water levels. It does have spines, they are slow growing but make a masculine statement.

The Jade plant, Crassula, is the genus of this specific plant, is a nice plant. It may have a problem with Mealy Bugs, so beware of little cottony masses in the crouches of the leaves. Water when the leaves become less turgid, when they become just a little soft, otherwise leave them alone. It may be several weeks between waterings.

We have received a huge number of emails this season. We thank you for you questions. One question that is popular is - "how do I fertilize indoor plants, especially those that don't flower?" First don't over fertilize indoor plants, remember the limiting factor is not water or nutrients but light. When there is a lack of light the plants metabolism is extremely slow. This means you don't need to fertilize as much. Wait until you see new growth on the plant, that is an indication the plant is growing. That means it is a good time to fertilize. Spring is a good time to fertilize, the days are getting longer, temperatures are warming and the plant is moving into a time that it will grow. To reduce the concentration of fertilizer use a good time release fertilizer. Mix it with water, they dissolve, making a perfect way to fertilize. A good ratio for indoor plants is one with a high middle number or Phosphorus. Phosphorus is responsible for root growth for both flowering and non flowering plants. It is responsible for flower growth so if you're looking for more flowers do two things. Use a low concentration of high phosphorus fertilizer and provide adequate light. Fertilizer alone won't
help, in fact it may damage or burn the roots. A slow release fertilizer that has been coated with a sulfur like material will move slowly into the soil when watered. But err on the side of too little fertilizer, not too much. A good indication that a plant isn't getting enough fertilizer is yellow leaves at the base of the plant.

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Photos and story by Monrovia Nursery Company

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