Can someone tackle a question regarding my cactus?
My cactus collection includes 20-30 large cacti (5 feet and taller)growing in half wine barrels and positioned around my yard in the Los Gatos/Santa Cruz mountains. Average temp through the summer is 5-10 degrees below temps in the valley….hot but not stifling. They get 2/3 sun, 1/3 shade through the day. I water them heavily every 3-4 weeks in the summer, every 2 months in the winter.
This year I am having trouble keeping them green. Healthy color has always been a minor problem, more prevalent in the summer than in the winter. This year is much worse. The tall varieties are all light green, with a couple of them tending to yellow. With every second watering, I use a very diluted measure of Schultz liquid plant food (10-15-10), approximately 3 droppers full (50-60 drops) per 5 gallons of water. Once a year in the fall, I add ½ cup of bone meal to each plant, not yet done this season. Is there something I can safely add to the soil that over time will improve their health and “green them up”, so to speak?
My naturally yellow varieties appear to be doing okay.
Thank you for your time.
If you can send us a picture, we can give you more specific info.
In general, yellowing is a sign of stress more common in the winter when they go dormant, not in the summer. If this started happening about a month ago, it could be because of the sudden heat we had back then. A lot of plants in the Bay Area, including cactus, got damaged.
We mix our own slow release nutrients for cactus, which we sell in 1 pint for $4 or 1 gallon for $18, and will ship. We prefer slow release to the liquids.
If your cactus has been in the same soil for many years, there may not be any soil left, and it may be time to repot them all.
Finally, you can try kelp meal to help green them up.