Of Milkshakes and Hummingbirds: Q & A with CNPS-San Diego


CNPS-SD recently received a query from a San Diego County gardener:

Q: “I bought a manzanita at your plant sale and I am about to plant it in the ground. Before I do, is there any recommended soil amendment or fertilizer that I should use? What type of fertilizer should I use after planting, and how often?”

A: In general, native plants do not need or want much in terms of fertilizers or soil amendments. They are adapted to living in rather nutrient-poor soils. The nutrients they do receive usually come from their own leaf litter. Manzanitas in particular hate fertilizers. A good analogy is that fertilizing native plants is like trying to feed a milk shake to a hummingbird. You should resist the temptation to add any fertilizer when you plant it or at any time afterwards. If you would like to read more about this, the Las Pilitas Nursery web site has a good discussion of manzanitas:

http://www.laspilitas.com/groups/manzanita_arctostaphylos/Manzanita.html .

Q: “I have a question about cutting back California Fuchsia, Salvia 'Pozo Blue' and California Encelia. I have cut back the Fuchsia previously but was too cautious and now it is getting an unattractive woody base. I would like to deadhead the Salvia – when can I do that? I have cut back the Encelia before and it seemed to come back readily. Can I do this every year?

A: You can deadhead Salvias any time from later summer to mid-winter, and you can prune them to the desired shape at the same time. If you want to feed the birds in your garden, scatter the cut seed heads on the ground, or you could put them in a bowl or something similar to make a feeding station. Birds such as finches and towhees love the seeds of Salvias. As you saw with your coast sunflower (Encelia californica), most natives come back vigorously from pruning when they get some winter rain. You can cut back the Encelia every year if you wish. Your California fuchsia should be cut back to the ground in winter and it will pop back next spring. Don't cut it too early as it flowers from summer through fall. It spreads by underground runners as well as seeds, so you may find it popping up in other parts of your yard. If you find it getting out of control, you can pull up the young shoots, roots and all, to keep it contained. 

Q: “I have heard about a 'good fungus' that lives in the soil and helps plants be more drought tolerant. What is this and how can I get it for my garden?”

A: What you heard about is mycorrhizal fungi. These fungi do indeed live in the soil and form a mutually beneficial association with certain plants. The extremely fine root-like hairs of the fungus can extract water from the soil better than the roots of green plants. However, the fungus lacks chlorophyll and cannot make its own food. In a classic example of symbiosis, mycorrhizal fungi provide water to green plants, and in return the green plants supply carbohydrates to the fungi. The best way to encourage mycorrhizal fungi in your garden is to follow this program:

  • Have a good variety of native plants
  • Use a combination of rocks and good quality mulch around your plants
  • Avoid herbicides but keep non-native weeds under control as much as possible
  • Avoid fertilizers
  • Avoid unnecessary soil disturbance
  • Keep soil relatively dry in summer. Lightly water no more than once or twice a month.

Q & A is a regular column of the CNPS-SD newsletter.  Please send your native gardening questions to info@cnpssd.org.