Note: The tips and notes below represent a body of knowledge that we have gathered from raising cactus plants in the USA.
Most notes are generalizations. Additional research into specific plant cultivation requirements is encouraged.
I. Raised Cactus Bed Preparation
In preparation of our outdoor cactus beds, the following steps were used:
- A south-facing area was chosen for the bed. This area receives unobstructed sunshine for a good portion of the day.
- The grass covering the area was removed with a shovel. The sod is used to fill in bare spots in the lawn.
- A shovel or tiller is used to turn the soil over upon itself.
- Builder's sand is added to the soil; estimate 1 part sand to 1 part soil erroring on the sandy side.
- Sand and soil is mixed together with shovel or tiller.
- To enhance drainage, soil mixture is shaped so that the bed is high in the center and tapers toward the ends.
- A small ditch is shoveled out at the bed's lowest point to divert water away from the bed.
- Cacti are planted and watered.
II. General Cactus Soil Mixture
Most cacti require a free-draining soil mixture to prevent diseases resulting from too much water. A one part potting
soil to one part builder's sand mixture is acceptable for most types. Some cacti, the epiphytes, are native to jungle
areas and receive their nutrients from trees. These epiphytes, including the popular Christmas Cactus and Easter Cactus,
do best with peat moss added to the soil mixture. A one part potting soil, one part builder's sand, and one part peat
moss mixture is the recipe that we use for epiphytic cacti. If you use peat moss be sure to wet it throughly before
adding it into the soil mixture.
III. Watering Requirements
During the growing season, cacti need to be watered when the soil approaches dryness.
It has been my experience that this results in weekly watering. The main thing that
we try to accomplish when watering is to completely saturate the soil. For potted plants, this means
that the pots are sometimes submerged in a basin full of water. A plant is considered to be completely
watered when all air bubbles stop arising from the soil. In winter, a
natural dormancy period for most cacti, watering is reduced. We usually water our plants
once per month during the winter using the method described earlier.
IV. Fertilizer Requirements
Cacti will benefit from a light fertilizer application during the growing season.
We use a partially diluted houseplant fertilizer on our plants. Some recommend
the application of 1/2 strength tomato food. No fertilizer should be given to the
plants during the winter dormancy period.
V. Lighting Requirements
Generally, cacti should be grown in full sun for blooms and good growth. The only exceptions are the epiphytic
species that are native to the shaded rain forests. Some plants can be sunburned from
too much light especially when moving from an indoor location to an outdoor location. This
usually discolors the plant. South exposure is best for greatest intensity of sunlight in the USA.
VI. Temperature Requirements
Temperature can kill or disfigure cactus plants. Heat generally
is not the problem; our plants endure afternoon temperatures in the 90s and
low 100s during the growing season. Plant tolerance to cold, however, varies from species to species. Most cacti that
we have owned tolerate temperatures to freezing (32F). A few conk out below 50F and some endure cold USA winters
with lows reaching 10F. Cold and excess water in the winter is a lethal combination. We've lost plenty of
plants due to this reason. The majority of our plants are wintered in the greenhouse where minimum temperatures
Each area of the world has its own indigenous weed species. The weeds that we battle
the most are spurge, nut grass, and Bermuda grass. You have to be careful removing weeds
close to cacti - I have many battle scars from not wearing gloves. A good action hoe and a three prong cultivator
come in handy during weeding time.
Cacti are not immune from insect attack. We haven't really noticed any problems with insects, however.
Ants seem to be our most frequent visitors. See our section on Cactus Pests for a
brief treatment of common insect problems.
The majority of our cacti are potted in regular, unglazed clay pots. Clay pots are porous and add to the
free drainage characteristic of cactus soil. Plastic pots can be also be used, however, extra care is required
to insure that the soil does not become waterlogged. Plastic pots hold water longer than clay pots. We don't repot
very often since most cacti don't mind to be crowded too much. A root or roots growing out of one of the pot drainage
holes is a clue that the plant needs repotting. Gloves, folded newspaper layers, and tongs are used to support
the cacti when removing it from the old pot and when placing it into the new pot. Some plants refuse to
give up their old homes, so, it is sometimes necessary to break the pot. New pots are generally 2 inches
larger in size compared to the old pot (i.e. a plant that is growing in a 4 inch pot is repotted into a 6 inch pot).
Stem cuttings: a portion of the cactus stem is cut off and placed in a warm, dry place for a few days for the
wound to callous over. Time is not critical - I've waited as long as 3 weeks for cuts to callous. After
callous develops, plant in soil mixture and water as usual.
Seeds: Growing cacti from seed is very enjoyable and is a great way to increase
the number of plants in your collection. Cactus seed originate from fruits that sooner or later
dry out and expose their seed. Some cactus fruits dry out naturally on the plant, however, some fruits remain juicy
for quite some time. Harvesting seed from these juicy fruits is much like getting grape seed from grapes. Paper towels are
used to dry these seed prior to storage. Once dried, cactus seed can be stored in tiny envelopes for convenience
until planting time. It is best to store them in a cool and dry area of the house. The seed remain fresh for several years.
Once the seeds are ready to plant, prepare or purchase your soil germination mixture. Any porous, free draining
soil mix will do; purchased germination mixes have the advantage of being sterilized and free from weeds/fungi.
Place the soil mix in small pots or, preferably, a plastic compartmentalized seed flat. Soak the mix
with water and let the water soak in. Since most cactus seed are very small, sprinkle them directly on top of the
soil. Some larger seed may need to be placed gently underneath the soil surface. Once the seed have been sowed,
cover the mix with a very, very small layer of fine sand. The sand will help to support the tiny plants when they
germinate. Place a transparent covering (i.e. glass, plastic) on top of the seed container to help retain moisture.
For small pots, placing the pots inside a Ziploc-style bag is ideal. Exact-fitting, plastic domes usually are included
in the purchase of seed flats. Place the seed in a warm location (i.e. 70F - 80F) that receives indirect sunlight.
Germination time varies from 3 days to months. It is important to keep the seed mix from drying out. When seedlings
appear and have taken on a green appearance remove the transparent covering. Young cactus plants appreciate fresh air.
Following germination, keep a close eye on watering and light requirements. Seedlings require more water than adult plants and the mixture should
not dry out. When watering, a fine mist should be used so as to not uproot the seedlings that are trying to get their roots established.
Strong light can sunburn seedlings very quickly, so, make sure that seedlings receive indirect light for the first few months after germination.
Cactus seedlings grow slowly, so, don't be surprised that the tiny
plants remain in the seed mixture for a long period of time (i.e. 6 mos - 2 yrs). Crowding of seedlings is not much of a problem and
may be beneficial. Transplant seedlings once their root systems have been established. It should be noted that the seedling
roots are fragile. Take care not transplant the seedling too early.