There are as many different potting soil recipes as there are growers. The proper mix will help with the common problem of over watering. After experimenting with different potting soil mixes, most growers will settle with one or two that work for them. The mix you chose should meet the following requirements:
- Be porous enough for good drainage and aeration.
- Be dense enough to support the plant.
- Be readily and economically obtainable.
Common Potting Soil Ingredients Are:
Perlite – A mineral that helps aerate and lighten the soil mix. Aids drainage.
Pumice – A mineral that helps aerate and lighten the soil mix. Aids drainage. Not generally available in our area.
Vermiculite – A mineral that helps aerate and lighten the soil mix. Retains some moisture so is less good for drainage than other additives and not recommended for cactus and succulent potting mixes.
Expanded Shale – Made from mined shale that is ground and kiln-fired into a porous, water-absorbent, gravel like substance. Aids drainage but is heavier than perlite.
Coir – Ground coconut husk. Adds organic matter without acidifying the soil. Breaks down slowly. Renewable resource.
Peat Moss – Mined from ancient peat bogs in the northeast US and other countries. Adds organic matter. Acidifies the soil. Breaks down rather rapidly. Difficult to hydrate. Non-renewable resource. Not recommended as an ingredient in most cactus and succulent potting soil mixtures.
Compost – Adds organic matter, structure, and nutrients. Utilizes a conservative resource. It’s free and you can make it yourself.
Forest Products (Tree Bark, Wood Chips, Saw Dust) – Adds bulk and organic matter.
Lava Sand – Finely ground lava material. Adds texture, trace minerals, opens up the soil.
Builders/Play Sand – Adds texture, trace minerals.
Sandy Loam Soil – Adds texture, trace minerals.
Dolomitic Limestone – Added to soils and soilless potting mixes as a pH buffer and as a magnesium source.
Wetting Agent – Help water penetrate into hydrophobic soils.
Decomposed Granite – Used in some potting mixes to increase drainage. Used as top dressing.
Two examples of a potting soil mix:
Example A: Example B:
4 parts commercial potting soil mix 1 bag of commercial cactus mix
2 parts perlite add perlite, course sand, or other
2 parts compost drainage material
2 parts sandy loam soil
2 parts lava sand
During the growing season, check your plants every few days and water more frequently than you water when the plants are dormant. Allow the soil to become dry before watering again. When you water, it is usually best to add water until the water runs out the drain holes in the bottom of the pot. Never place the pot in a saucer or other vessel that allows the pot to sit in water.
In the winter, most cacti and succulent plants are dormant. However, most plants will need some water during the winter months. This will depend on the plant species and your growing conditions. Some plants, particularly cacti, will do fine without water for several months during their dormant period.
Most cactus and most succulents require strong light to grow well but many cannot stand direct sun. Knowing your plant name is the key to proper light exposure. Most plants thrive when placed outside during warm weather but will need to be acclimated slowly so as not to be sun burnt.
Liquid or water soluble fertilizer should be used at one quarter of the recommended strength. You can apply the diluted fertilizer with each watering while the plant is growing. Discontinue fertilizing during the dormant season. Most plants do not require fertilizing during the first year after repotting. Fertilizer for cactus and succulents should be low in nitrogen. Peters 20-20-20, Miracle-Gro tomato fertilizer, Super Bloom, or bone meal are some good choices for most cactus and succulent plants.
There are a number of insects that can be a problem for growers. To control most of these insects, we recommend trying the most benign treatment first. That is the use of a squirt bottle filled with water. Spraying a stream of water on insect pests will dislodge them and they will usually not re-attach to the plant. Sometimes the addition of a few drops of dish washing liquid to the spray helps.
For severe infestations, more stringent methods must be used. Always follow the manufacturer’s directions closely on all insecticides. It is usually best to do a test treatment as some treatments will harm certain plants or leave residue on the leaves.
The insects you are most likely to encounter are:
Mealy Bugs: If only a few mealy bugs are present, you may pick them off with tweezers or blot them with a q-tip which has been dipped in 70% rubbing alcohol. The next level of treatment should be with horticultural oil such as neem oil. If the infestation persists, use a systemic insecticide containing imidicloprid.
Root Mealies: Elimination of root mealies usually requires that the plant be removed from its container and all soil removed from the roots. Discard the soil, wash the roots with a stream of water from a garden hose to remove the mealies, and re-pot the plant. Then treat with a systemic insecticide containing imidacloprid.
Spider Mites and Aloe Mites: These tiny mites are present in our environment and can appear at any time. They are often encountered in greenhouses. The most effective control is with a spray insecticide containing pyrethrins and sulfur or spinosad. Repeat the treatment after five days and, in the case of aloe mites, the affected plant tissue should be removed.
Scale: If the scale infestation is on a landscape plant these pests can usually be dislodged with a strong spray from a garden hose. If the infestation is on a small pot plant the insects can usually be cleaned off with a stiff brush such as a tooth brush. Eventually an insecticide is usually required to prevent re-occurrences. Systemic products are usually the most effective.
Stink Bugs (Chelinidea vittiger): These insects are particularly problematic on cacti and Dyckia plants. Their habit of sucking the juices from the plant leaf will leave light colored spots. Horticultural oils will control this pest when in the nymph stage but will not eliminate the adult form. Adult insects must be captured and mashed with large tweezers or controlled with an insecticide containing imidicloprid.