Growing Cacti in Your Home
If you have a brown thumb (which I don’t believe for a moment!) why not try growing cacti? They are fascinating plants, easy to care for, come in an endless supply of varieties and are drought tolerant. They also do well in homes with low humidity.
Cacti are symbols of protection, warmth, power and resilience. In Feng Shui they protect the home against negative energy and misfortune. When combined with succulents, they make a beautiful landscape of different textures, shapes, colors and flowers. Some have spines, fuzzy hair or both.
The cacti genus can be divided into two groups; forest cacti and desert cacti. All are native to the Americas.
Forest cacti, in their outdoor native habitat are usually epiphytic, like part shade, and the higher humidity in sub-tropical and tropical forests. An example of forest cacti are Christmas cactus, Easter cactus and Orchid cactus. The flowers are outstanding on most varieties with some even being fragrant.
The second type are desert cacti which we will be the focus of this article. There are thousands of varieties of desert cacti that come in all shapes and sizes. Many varieties have spines that are actually modified leaves. They not only provide some shade for the plant but also protect it from predators. The spines come from small bumps called aeroles, which also produce branches and flowers.
Cacti bloom outside in the summer. Depending on the variety, blooms can be orange, pink, red, yellow, white or purple. Some cacti will produce tiny low groups of flowers, while others have large beautiful blooms. Many can be grown in the home either in a very sunny window or under grow lights. Some will tolerate part sun so do study up on your specific cacti and its care. Never introduce a cactus to a full sun environment immediately after you get it home. Believe it or not, cacti can actually sunburn if not acclimatized to a new environment. Slowly introduce it to a full sun location of 4-6 hours per day. Under the right growing conditions, cacti in the home can live for ten or more years. Cacti in their native environment can live for 300 years!
Most cacti do not bloom indoors. You may have good luck if your days are warm and nights are very cool (10-12 C). Remember that desert cacti in their outdoor natural habitat are used to very chilly nights (down to 2 degrees C)
During the spring and summer growing period, cacti need water and nutrients. Do not let them dry out excessively. Acclimatize to the outdoors in summer when night temperatures are consistently 10 C or above.
During the spring and summer desert cacti should be regularly watered when their container soil is almost dry. Do err on the side of under-watering as opposed to too much water. It is very important to not let the pot sit in water after watering. This can lead to root rot.
From April to September feed once monthly with an organic water soluble or liquid cacti/succulent fertilizer low in nitrogen – Ex: 5-10-10 or 2-77.
If needed, cacti should be repotted in spring. The best pots are shallow terra cotta clay pots that have been fully soaked in water for at least two hours prior to use. This prevents the pot from pulling any moisture away too quickly before the roots can use it. Clay pots also provide good airflow through the soil and release extra moisture through the pot walls. The new pot should only be one size up from the original. Ex: 4 in to 6 in. or 6 in. to 8 in.
When repotting, I suggest you use ProMix Cacti/Succulent Soil. You can add a bit of fine gravel and/or perlite which only improves soil drainage and aeration.
Prepare your repotting area first. You will need thick gloves, tongs, and long strips of newspaper, twisted together to form a ‘rope’. Loosen the soil around the pot rim with a knife. Wrap the twisted newspaper ‘rope’ around the cactus; grasping the two ends close to the plant. Lift it up and out of the pot.
Plant the cacti at the same soil level it was in the old pot.
Water after repotting with tepid tap water that has sat out on the counter for a couple of days or room temperature rain water. Ice cold water and ice cubes are not recommended.
Cacti need to rest in winter. November to March is their dormant period. Water only when the soil has completely dried out. Make sure they are placed away from drafty doors or windows.
Propagation of cacti is by seeds, cuttings, offshoots (new growth) or pups. Pups grow at the base of the plants. While they are growing the mother plant provides them with water and nutrients.
To harvest pups, sterilize a very sharp knife and wear gloves. Cut the pup away from the mother plant at the base at a 45 degree angle. A slanted angle allows the wound to callus over before it rots. Dip the callused end of the pup into rooting hormone powder and gently shake off the excess. Gently press the end into the top of the new, slightly moistened, growing medium. Place in bright but indirect sunlight. Roots should develop in 4-6 weeks.
Starting cacti from seed requires a ton of patience but is a fun project to do. Start your project in late winter, spring, or early summer. Cactus seed can be bought in assorted variety packs in garden centres or from seed companies.
Soak the cactus seed in water for half an hour. Drain off the water and gently clean the pulp off the seeds with a q-tip.
Most cacti seeds need to be stratified before planting. Put the seeds in a Ziplock bag, add a handful of cactus soil and place in the fridge for a month. Keep the soil in the bag slightly moist.
Plant the seeds in a shallow tray, in moistened peat/cactus soil; as deep as they are wide. Lightly moisten the soil. Cover the tray with clear plastic. Place in a bright location out of direct sun. Most will germinate in approximately 3 weeks. Remove the plastic cover only to check on the soil moisture and once the seeds have germinated. In about six months they should be ready for their own pots. Did I mention this requires patience?
Pests and Diseases
Cacti can experience insect pests such as scale, mealy bugs, spider mites and fungus gnats.
Fungal Rot – Dark mushy spots on the stem.
Bacterial Rot - Bacterial rot can cause your cactus to ooze a black liquid. This can occur at the base of the plant or growing tips. Remove tiny affected areas and treat with a diluted hydrogen peroxide solution. If there is too much rot, throw the plant away.
Overwatering – The cactus will turn yellow and/or experience brown mushy spots.
A word about cactus corking.
Older cacti may experience a natural process called ‘corking’. This is not a disease. The cactus will develop a partial brown protective layer that resembles cork bark. Corking usually starts slowly around the base of the cactus. When pressed, it is quite hard. Corking protects a cactus and provides older, large and heavy cacti with support.
As I mentioned, this is natural, so do not attempt to remove it.