by Hank Andresen, HCSS
Growing in your home - a southern window with bright light is preferred.
In a greenhouse - you have full control of the environment.
Outside in pots - provide some form of cover, under eaves of your home, or a covered patio with bright light.
Outside beds - you will need porous soil in raised beds and a lot of TLC.
Growing all Cactus, all Succulents, or both?
Note: All cacti are succulents but not all succulents are cacti.
Clay - Clay dries out faster than plastic or ceramic pots. Use shallow azalea pots, or bulb pots.
Plastic - Black, dark green, or gray if possible. White and bright colors have a tendency to degrade and break while being handled.
Ceramic - Expensive but dresses up your collection. Avoid highly decorated pots.
1/3 Easy GRO Premium potting soil or equivalent.
1/3 large per1ite or pumice.
1/3 coarse sand or fine gravel (like aquarium gravel). Captan or any good fungicide mixed in with your soil mixture.
Water thoroughly and allow to dry out completely before watering again.
During warmer months (March to October) water every 7 - 10 days.
In cooler months (November to February) water carefully every 3 - 4 weeks. However, some cactus should be kept completely dry during this dormancy period.
Any low nitrogen fertilizer 1/2 strength once a month. Be sure fertilizer has all the trace elements including boron.
Ozmocote can also be used in lieu of the above.
Use BR61 in the spring to promote "super" blooms.
Plants can sun bum if put in direct sun without acclimating them first.
Give plenty of air circulation such as fans in your greenhouse.
Think in terms of quality - do not sacrifice this for quantity.
Do not water during overcast days or rainy days.
Temperature, amount of light and ventilation all affect the drying time of your soil.
Fine gravel, crushed granite, marble, limestone and small rocks all make excellent top dressing.
Most insects can be removed by hand or a strong stream of water. Use pesticides as a last resort; remember we do have beneficial insects, such as ladybugs, assassin bugs, praying mantis, green lacewings, Trichogramma wasp, etc. Ladybugs (many different species) feed on aphids, cinch bugs, whiteflies, mites and many other soft-bodied insects and eggs. We all need to get to know these friends of the gardener and of course us "CACTUS NUTS
Liliana Cracraft, Paulette Patterson, Stan Russ, Dave Thomas, Noreen Toleman, and Richard Stamper. Houston Cactus & Succulent Society.
1. Over watering.
Over watering is one of the most common problems when growing cactus & succulents. As a general rule, plants should be watered in the summer on a 10-14 day intervals in well-drained soils. More often if the soil is sandy and less often if the soil is heavier (clay). In the winter, irrigation should be reduced because most cacti go dormant. Best tip for the summer: learn about your plant water needs by checking the root zone 2-3” below the surface before watering. It should be dry. If in doubt, don't water.
2. Not watering enough.
“Cacti do not need water” is a myth. They need water to live just like any other plant. Temperature has an effect on the rate of desiccation. Many C&S do not need to be watered over the winter, but is best to give them a little bit of water to prevent the loss of roots. If a plant's roots have dried up, water it very lightly until roots take hold again.
3. Not providing the proper amount of sun light.
Just because cacti and succulents are often found in arid habitats, doesn't mean they can be placed or planted in full sun. Many species grow where they get a degree of shelter from rocks, larger plants and the environment. Growers should be cautious as they place their plants from a sheltered position into more light. Young barrel and columnar cacti and some yuccas can be sunburn and the scars are permanent. Best tip: Use a shade cloth (30%) to protect plants form the fierce summer sun. On the other hand, not exposing the plants to enough sun light creates pale, sickly, or abnormally-looking plants (etoliation). Best tip: Rotate plants often to expose the whole plant to the same amount of light.
4. Trying to grow plants not suitable for Houston’s weather.
Many of the plants offered at nurseries are sure casualties of Houston weather because they have been grown in greenhouses under protected conditions. Better to choose plants that have a chance, such as many Agaves, Opuntias (prickly pears), Aloes, Haworthia, Gasteria, Kalanchoes and Euphorbia. Many Echeverias, Semperviviums (hen & chicks), Sedum, Lithops, Pleiospilos (living stones), and a number of cacti do well during our mild days, but can die in the summer heat. Best tip: Plants should be protected in the winter for temperatures below 40º F.
5. Failure to use the proper soil mix.
Many beautiful and inexpensive plants from local nurseries are planted in a peat-based medium. This medium is hard to water correctly and inevitably becomes too wet or too dry. We recommend using a commercial cactus potting soil, but mixed with something like perlite, sand, or small gravel. This way, you’ll have a fast draining medium that is much more suitable to Houston weather. Good soil mixes for Lithops include 10%-20% potting soil to 90%-80% gravel. For most cactus and succulents a 30%-40% potting soil to 70%-60% gravel is recommended. A 50% potting soil with 50% pearlite is a good mix for succulents like Sanseverias (snake plants), small agaves, and yuccas. A 50-60% potting soil to 50%-40% gravel is suggested for leafy succulents like Adeniums (Desert Roses). Best tip: soil used for cactus & succulents must have some draining material.
6. Ignoring the plant’s requirements for growth.
It is very important to know the growth habits of your plants. For example, most cacti and succulents should be grown at temperatures between 75-90ºF, and some may require trace minerals in the soil. These can be provided by fertilizing, but the common fertilizers must be used appropriately, usually at ¼ strength, or a slow-release product should be used. Best tip: A fertilizer for tropical plants is perfect. If your plant is variegated (light or pale green tinging towards white or silver), use a fertilizer with a lower content of nitrogen.
7. Leaving plants root-bound too long.
The roots must have enough room to grow and thrive. The roots of plants that have grown in a pot for a long time completely fill the entire pot in a tight mass. This creates desiccation problems because water may have a hard time penetrating the mass. The roots also cease to acquire nutrients and the plant could perish. Best tip: Repot when roots begin to show through the draining hole.
8. Poor planning when landscaping.
Landscaping with cacti and succulents is becoming very popular, but poor planning may result in a disaster. Some key elements for success include building a raised bed by mounding the soil, or even constructing a large in-ground planter. This is similar to a raised vegetable planter. The bed should be elevated 8” to 12” above the surrounding area. A raised bed promotes drainage; an absolute if you want to be successful with a variety of cacti and succulents. The soil mix must be fast draining, but not too lean. A combination of expanded shale or pea gravel, with sharp sand and compost is a good general purpose blend. Test your blend. Water should not stand on the surface more than a few seconds before entering the soil. Plant early in the spring if possible, and be prepared to shelter plants under netting until they are fairly well established. Best tip: Choosing the right landscape plants is best done with advice from those who have had success. Lay down one or two layers of weed block. Cut “X”s in the weed block and plant your plants through these “X”s. Use gravel, decomposed granite or clean crushed stone as a mulch/dressing for a finish treatment.
9. Planting Incompatible plants in a dish garden.
For a dish garden use cacti and succulents with similar growing conditions. Use plants with watering at the same time such as ball type like the Golden Barrel (Echinocactus), and taller growing White Lace (Echinocereus) cacti, or maybe succulents with elongated or thick fleshy leaves. Use plants with the same growing seasons such as Zebra Plant (haworthias) and Black Head (aeonium) for winter time, or Jade Plant (crassula) with one or two of the Hen & Chicks (sempervivum, echeveria).
10. Burning plants due to phototoxicity.
Overall, cactus & succulents do not get infested by insects (such as scale) as often as other plants. However, they are susceptible and on occasion we must treat them with insecticides when manual removal of bugs is not enough. Plants treated with chemicals must be protected from the sun; otherwise they will get burned easily, especially with products that contain oils. Best tip: isolate plants with scale or other insects, and protect them from the sun.
This article was originally published in the 56th issue of the weekly e-newsletter Lazy Gardener & Friends of May 2, 2014. Reprinted with permission.