Two teaspoons per gallon. That is Don's recipe for improved plant health.
Two teaspoons of white vinegar per gallon of water is what Don Campbell, a local cactus and succulent expert, recommends to use to water these plants. The vinegar drops the pH of the water to about 4.5. While this is on the high side of acid, it is a great pH for most houseplants whether they are succulents or not.
Lowering the pH of the water helps release nutrients and improves the overall health of the root system. Some potting mixes, especially mixes used for cactus and some succulents, are very well drained. These soils typically have low levels of plant-available phosphorus. Lowering the pH of the water helps release phosphorus for plant's use. Lowering the pH too far can release aluminum and other micronutrients in quantities that can be toxic to the plant. Acid-loving plants like gardenia, rhododendron, and Easter lily can tolerate and even benefit from a lower pH so adding more white vinegar to the water for these plants is recommended.
Don suggests using the vinegar and water mix every time you water your houseplants. In the spring when days are longer and nutrients are in more demand, house plant fertilizer can be added to the vinegar and water solution. Don't use more of the fertilizer than recommended on the product label; fertilizer is a salt and salt kills roots.
Neglecting to water your plants during the winter will also result in root death. Unless you maintain a high humidity in your home, houseplants dry out much quicker in the winter than during the summer. You can probe the soil with your finger, use a soil moisture probe, or lift the pot to determine if you need to water. The smaller pots will usually need to be watered more frequently so don't forget to check them more often than the plants in large pots.
When you water your pots, ensure sufficient water is applied to run out the holes in the bottom of the pot. Even then you may not have wet the soil sufficiently. At times the soil will pull away from the pot creating a gap that allows water to run out of the pot without wetting the soil. Peter told me he waters his houseplants by soaking them in a bucket full of water. I've done the same thing in my bathtub. When air bubbles quit escaping the soil in the pot, the soil has been thoroughly soaked. Don't allow the pot to stay in the bucket any longer or root death can occur. Using the bucket-watering technique can result in the spread of root diseases from one pot to another but may be necessary if the soil is not being wet sufficiently to ensure the health of the plant.-
When you water from the top, apply sufficient water to wet the soil and then apply the same amount of water to leach salts out of the pot. You don't have to do this if you use the bucket-soak technique. Unless you use distilled or reverse osmosis water, you apply salt every time you water your plants. These salts will accumulate in the soil if you don't wash them into the saucer. To keep the salty water in the saucer from being sucked back into the pot as the soil dries, you need to empty the saucer of its of water, or use a trivet or other device to raise the pot above the water that accumulates in the saucer.
One of my cactus-like succulents, a red Euphorb, Euphorbia trigona rubra, had a fungus called Fusarium spreading along its main stem. This fungus was also starting to infect some of the arms of this succulent plant. I took the plant to the last month's meeting of the Chinle Cactus and Succulent Society and offered a piece of the plant to anyone interested in adopting. Don cut arms off this three-foot tall plant for anyone wanting to take home a cutting. Each cutting was checked first to ensure it was free of the fungus.-
This Euphorb oozes a white latex fluid to which some people are very allergic. Each cutting was wrapped in paper to transport it home and protect the adoptee from coming in contact with this ooze. -
Before the cutting could be rooted it needed to cure for up to 10 days or longer and then stuck into a pot of soil to root. With time, each cuttings will reach the height of the original plant and be a beautiful accent plant in the home.
Dr. Curtis E. Swift is a retired horticulture agent with the CSU Extension. Reach him at Curtis.Swift@alumni.colostate.edu or check out his blog at http://SwiftsGardeningBlog.blogspot.com. He owns Swift Horticultural Consulting and High Altitude Lavender.