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
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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