Closet Cactus Care by
Starting from Seed
For the non-professional cactus lover starting cacti from seed can be a daunting task,
especially for those without a greenhouse and experience. But growing these beautiful
specimens of the plant kingdom should not be limited to those who are mass producers.
Everyone should have a chance to start their own cacti from seed and slowly watch them as
they grow and form into mature specimens. With the right resources and techniques the cactus
enthusiast should find success, even if that is within a well lit closet.
Seeds and Soil:
Of course first thoughts must be given to what seeds to grow. There are a number of very
reputable cactus plant and seed dealers, my own favorite being Mesa Garden of Belen, New Mexico. This company
has thousands of different species of seed to choose from. Mesa Garden, and many other seed
sellers, can be located at the Cactus and Succulent Plant Mall home page at http://www.cactus-mall.com.
Soil choice among the professionals can be quite an intricate endeavor. Many cacti have very
specific ecosystems that they have evolved in, but until you become much more involved in
cacti care you can simply use the general cactus soil that can be purchased from your local
nursery or garden center. If you are looking for a quality general purpuse soil I would
recommend ordering from Bob Smoley■s GardenWorld, or many of the other cacti dealers
found at the Plant Mall. Many professionals are now using mixes with 50% pumice with good
results, but a general mix could consist of 2/3 potting mix to 1/3 pumice.
Besides the seed and soil other needed supplies are small plastic pots, a regular sized spoon,
2 deep microwavable bowls with lids (preferably glass, one large and one small), a set of
tweezers, a can of disinfectant spray, a bottle of bleach, and some ziplock baggies. I would
also recommend that only distilled water be used for soaking the soil and any future misting
of the soil or seedlings.
Getting the soil ready and killing off all contaminates is the first step. Make an estimate of
how much soil is going to be needed to fill the number of pots that are going to be used
(remember, seeds should be set in the soil no less that one half apart, but an inch is best).
Take the soil and put it in the large glass bowl and slowly add distilled water and mix till it
is minimally wet, trying to eliminate all dry spots. The soil should not be so wet as to make
it difficult to work with. Microwave for about one minute for each cup of soil. The steam
created through the heating should be enough for sterilization. Use the small glass bowl to do
the same procedure with sifted soil, but this time use only about 1/4 the original soil amount.
This will be the soil topping for the pots and allow for the seed roots to dig in. After both
containers of soil are sterilized let them cool. I recommend letting it cool with the lids on
since it will help the soil avoid picking up airborne spores. This may of course take some
time, so get cleaning.
Disinfect all the pots and tools by placing them in the sink with a gallon of warm water and
a tablespoon or two of bleach. Let them sit for a while. If they are previously used they
should be scrubbed with a clean unused sponge, being careful to remove all dirt and mineral
buildup. This step will most likely save you from the horror of fungus engulfing your seeds
and seedlings. Many simply avoid this step by using a fungicide in the soil, but often this will
lessen seed germination rates, something that the closet cactus grower, with few seeds, cannot
afford. Finish up by using the disinfectant on the counter top and placing the clean pots and
tools out to dry on a clean towel. I am of course trying to stress that all items used the
process, from towels to tweezers, need to be thoroughly clean and free of mold and fungus
An easier way to sterilize the soil is possible and quite handy if you are just sowing a small
number of species. Simply put the soil in the pots as described below (but without the seeds)
and microwave for an appropriate amount of time. Of course be sure that you do not cook
them to long, leading the plastic to melt. I generally will put the pots in a large ziplock baggy
that is partially closed, thereby lessening the dissipation of the soils moisture content. Then
you can just let the soil cool a bit in this large bag, remove and sow, and then place into
smaller bags for the germination.
Sowing the Seed:
Once the fine topsoil is ready, being slightly warm (80 to 85 degrees), start by filling each
pot full with regular soil and then with a very thin layer of sifted soil on top of that. I
personally use square 2.5■ (6 cm) plastic pots. Gently press the soil down with your spoon,
but not too much, it needs to stay rather loose. Give a spraying from a misting bottle to settle
and even out the top layer of soil. Make sure the soil is relatively wet but in no way sopping
wet. Now just take your tweezers and place the seeds on the soil and press them halfway into
the soil. Give about an inch between seedlings as you should probably keep them in these
containers for at least a year.
Now you are ready to bag them up. Two 2.5" pots fit perfectly into a small ziplock. The
trick in bagging them is to make the bag like a tent. This will cause the condensation buildup
within the bag to run down the sides and collect at the base of the pots, possibly to be sucked
back into the pots through the bottom holes. If a horizontal ceiling is above the pots droplets
of condensation may fall directly on top of the newborn seedlings, often displacing the
seedlings or causing them to rot easier. The easiest way to make such a tent is to place the
pots directly on the crease that is at the bottom of the bags. This would mean the ziplock is
directly above the pots.
Creating the Right Environment - Heat and Light:
Now that the seeds are bagged up it■s important to create the right growing environment of
heating and lighting. This is possibly the most critical aspect of growing your own cacti from
seed. My own method is to place the baggies onto a reptile heating pad that can be purchased
from a pet store. I have forgotten the brand I use, but it is very thin with a clear lamination
on it. There are a couple different sizes available, but they are rather expensive, approximately
$40 for the larger one. You may want to place a small thermometer (sterilized) within one
of the bags to make sure the internal temperature does not get excessive. Best germination is
at about 80 to 85 degrees, but a night temperature around 65 to 70 degrees is also necessary.
I simply have my heating pads and lights on a timer. A 14 to 16 hour cycle of light and heat
is good. Dependent upon what type of lighting you use, its heat levels, and the environment
in which the baggies will be placed, you may not need heating pads. I start my own seeds in
the unheated basement of my house which usually will run about 65 degrees for the duration
of the winter, having sown my seeds in the Fall so that they will be ready to acclimatize to
natural conditions in the Spring.
For lighting I use two 40 watt 4' long shop lights with two florescent tubes. These are
elevated about 1/2' to 1' above the seed containers. This is usually fine for the germination
phase but may turn out to be too much light for best growth. Many people believe in putting
the lights upwards of a couple inches from the soil level, but I have found this is not always
necessary. It must be kept in mind that though cacti are typically desert plants they germinate
and have much of their initial growth in cracks and crevices in the soil or under the shade of
other plants. A clear sign that there is too much light is that the seedlings will stop growing
and get a reddish/brown color. If this occurs you can use cheesecloth to lay over the bags as
needed. Germination should take anywhere from a week to nearly a month, so be patient and
avoid opening the baggies and letting in contaminates.
After about two or three months you can remove the pots from the baggies and keep them
under the lights and on the heating pad cycle. Some people have been known to keep the pots
in the bag for up to a year. If you find it necessary reapply the cheesecloth as needed once
removed from the bag. If you begin to notice seedlings dying off after they have germinated
make sure to remove the pots from the bags and allow the soil to dry out some, then follow
the watering directions given below, but with added fungicide.
One additional measure I take to help recreate a natural environment indoors is to add a small
fan to my timing system. I place the fan directly above the cacti on low and allow it to blow
gently throughout the area of my exposed cacti. Not only will this help limit any fungus and
green mold growth, but it will also help with the all too common gnat problem. Another way
to limit fungus, gnats, as well as retain soil moisture, is to apply a layer of desert sand or
small gravel around the seedlings once they are large enough.
Once the new seedlings are out of the baggies watering will become important. Seedlings will
need more water than mature cacti, but they also stand a better chance of getting root rot. I
personally recommend that the top layer of soil should come close to being dry before re-
watering. When watering is needed the pots should be placed in a dish of room temperature
water, allowing the water to rise through the bottom till the topsoil is moist. One can also
regularly apply a fine mist with a water bottle. Distilled water produces healthier seedlings
than tap water, but rain water is the best for watering as it contain trace minerals. If you
decide to use a top cover it may be necessary to learn how to use pot weight as an indicator
of watering time. Do this by learning the weight of the pots when fully watered. When the
pot becomes noticeably lighter be sure to water. This is also a good technique for checking
adult plants as well which might have rock cover.
Though my technique does not often afford rapid growth it should lessen the chances for rot,
thereby securing that the small closet cacti grower has his or her limited amount of seed
succeed. Following the directions of a good 1-7-6 fertilizer such as Sudbury Cactus Juice may
possibly increase survival rates by strengthening the plants natural defenses. As with any cacti
fertilizer it is necessary that they be fed from the bottom only, otherwise mineral deposits will
built up on the cacti themselves and can cause burns.
Growing Seedlings Outdoors:
Since I am in a northern clime I find it best to start my seedling by the above method indoors
in the Fall with the anticipation that I will put them outdoors after six or more months of
growth. It is very important that when placed outdoors the seedlings receive no direct sunlight,
but are instead placed in a nice shady spot that gets diffused light. As with artificial lights to
much sunlight will be readily recognizable by the reddening of the cacti. In this case the cacti
can be moved to a less bright spot or else a shade screen can be used to cut back the light.
My own method is to use replacement screening for screen doors and windows that can be
cheaply purchased from your local hardware store in rolls. This screening can be doubled up
until the needed level of protection is found. Such porous screening also allows for needed
air circulation as well as protection from the occasional cacti eating bird. Of course one can
also purchase professional growers shade screening.
Once your seedlings have grown to about a half inch to an inch you might want to consider
transplanting them to a new container with fresh soil. Let the soil first dry out a little. It is
best that the soil is not fully wet, but also not fully dry, at which point it might harden up and
encase the roots, causing the young rootlets to tear off when removing from the soil. Many
species have their best growth in a relatively root bound environment so it is recommended
that the cacti be little more than one inch away from the containers edges. Some cacti,
especially those with tuberous roots such as Ariocarpus and Turbinicarpus also love to dive
deep into the soil so be sure to provide them with adequately deep containers.
Once the seedlings are transplanted to new containers and on their way to maturity, it is time
to start testing out their natural sunlight capabilities. As with all cacti, young or mature, a
sudden move from shade or partial sun to full sun is not recommended. Such a sudden shift
in environments can cause the plant to get unsightly sunburn marks. It is best to slowly move
them into more sunlight over the period of a couple weeks, taking care to watch for browning
or reddening over. Immediately move the plant back into more shade if this occurs. And
remember, though your cacti received strong artificial light indoors they still might not be
capable of handing a rapid shift to strong natural light.
Grafting Your Seedlings:
Now that your seedlings are large enough you might want to consider grafting. Grafting is an
excellent method for increasing the growth rate of many of the clumping cacti, but is typically
not done with columnar cacti. It is also used to propagate species since a graft will reach
maturity quicker, thereby setting off many ■pups■ that can then be taken and grafted
themselves. The principle here is to use a fast growing columnar species as a base plant and
graft a slower growing clumping species onto it.
Start by selecting a nice columnar cactus for a base that is at least 4 inches tall, such as a
Trichocereus pachanoi or Myrtillocactus geometrizans. If the two cores do not match in size
it is very important that you at least cause them to connect at some point.
Now simply use a very sharp and sterile non-serrated knife to cleanly slice the base cactus
horizontally, being careful not to saw through the plant. It■s important that at this point you
trim the edges of the base plant at a 45 degree angle all the way around while leaving a flat
area equal to, or a little larger, than the diameter of the scion. This is important so that as the
scion grows it can basically "roll down" over the edge of the base plant during
its active growth. If you don■t cut the edges it is very possible that the scions outward and
downward growing pressure will cause it to pop off the base plant.
When you slice the scion plant be sure that it is cut very cleanly and without having to apply
much pressure. Such pressure may cause bruising of the seedling or young plant which may
in time become infected. Place this cut cacti directly on top of the center core of the base
plant, or slightly off center if the cores are of unequal diameter. My own way of ensuring the
graft is to use two rubber bands wrapped around the base of the pot of the columnar and over
the top of the graft, each rubber band being at right angles to each other. This can at times
be very difficult so it is very important that you take your time applying the rubber bands,
being very careful that they are loose enough so as not to apply undue pressure on the graft
and cause it to burst open at the sides, thereby effectively ruining the young plant.
Once the rubber bands are properly secured the graft should be placed inside a slightly humid
environment for a number of days to allow the two to grow together. If the graft is not kept
humid often the base plants cut edges will start to rapidly dry and sink, often causing the
proper connection of the two plants to fail. My own technique is to place the watered plant
within a ziplock bag under lighting for a few days. Depending on the size of the graft I may
also simply place a baggie over the top of the plant while spraying a mist of water into the
bag to keep up the moisture. After a short length of time the base plants exposed flesh should
have callused over and two plants should be securely formed together. They can then be
removed from the bag and cared for normally. After 2 to 3 weeks the rubber bands can be
One of the most current grafting techniques I have heard about is to simply place the scion
onto the base material as illustrated above and to make a ring of superglue around their
connective points. Then one simply needs to hold the plants together with pressure until the
glue is dry.
Other tips for successful growing of a graft plant might be in order here. The first is that
often new shoots might arise from the base stock of the graft. Often one might want to let
them grow a few inches and later cut them off to be used as graft stock. If this is the case
then the limb can be cut off as close to the parent plant as possible after reaching 4 to 5
inches and then one can follow the above directions. Since the stock will not yet have roots
the rubber bands can be placed around the base of the plant for a few days. Once the graft
is secure remove the rubber bands and place the plant upright in a dry environment. After a
couple weeks the open cut at the base should have callused over and the plant is ready for
planting. If you would like to grow this cut off limb then simply allow it to callous over and
then plant an inch or so into the soil. If you don■t want these limbs to zap away the growing
power of the scion plant then they should be pinched off as soon as they are noticeable.
Many closet cactus growers like myself who may not have a year round greenhouse or live
in the appropriate environment will need to find ways to provide for the plants over the
winter. With my own cacti I simply slow down watering in September and water only a
couple times in October, dependent upon the weather conditions. I also attempt to prevent the
rain from soaking them by putting them under cover of roof or tarp. Once the outside
conditions begin to consistently fall around 40 degrees at night then I look to bring them
indoors for hibernation; the soil being dry by then. Having slowed down their growth outdoors
due to the lessening of water they generally do not grow once I bring them in. The medium
and large plants are set downstairs and receive little light. Most of them end up in a couple
corners of my basement, one of which get a little bit of sun from a window in a southfacing
basement staircase. Though some have been winterized in complete darkness they do not
appear to be any worse off in the spring than the ones that received minimal light. I also use
a small selection for decorative purposes and place them around the house or office, on the
window ledges or the end tables. Unless the plants are starting to show moderate dehydration
I will not water them at all for the entire winter.
A couple faults of hibernation are root die back and no growth. Since the small roots receive
no moisture and are much thinner than the main root sections they will often die. This leads
to the slower formation of new growth the following season since energy for growth is being
pushed into formation of new roots. There is really not much that can be done about this
except to water, but watering, along with insufficient light, will lead to etiolation, the
yellowing of the flesh along with uncommonly thin growth. Such growth could kill the
aesthetic qualities of the cactus.
Most of my smaller seedlings will be placed under lighting while the newest seeds are sown
at the same time. The yearlings receive water as soon as the soil is dried out. If some of the
smaller plants in hibernation are showing signs of dehydration I will usually place them under
the lights and water till they have regained some of their former glory. Once the small plant
has regained its strength I let the soil dry under the lights and then place it back in the dark
for continued hibernation.
Growing for Aesthetics:
All my plants are grown for their beauty and so I feel that it is important to maintain the
proper conditions that support this. By following the already mentioned hibernation technique
one can generally keep a plant for years which maintains a standard diameter and shows only
a small pinch in the stock which represents the yearly growth point. Since the columnar
cactus■ diameter is dependent on the amount of sun it receives it often happens that a plant
grown in the south will have a larger diameter than it would in the north. Usually I will for
example get a 4■ columnar that once acclimatized here may only be 3■ in diameter. Since
such a sudden change is not very pleasing to look at I will usually let the new growth form
for a season until there is at least 4■ of new vertical growth on the 3■ diameter stock. I will
them remove this acclimatized section and re-root it. I may then also cut off the section of
the base plant that shows tapering, possibly to re-root itself if it is significant enough. I then
at least have a nice voucher specimen in the tip to grow completely to form and a short large
base of equal diameter that can be either grown to form or from which clippings can be taken
for further specimens or trading. It may be advantageous with the base stock to cut the
tapering section off at a 45 degree angle so that water does not collect on the tip and lead to
By following many of the above techniques, and incorporating those which have worked for
you in your environment, you should be on your way to maintaining a very nice cactus