I’ve gotten several emails lately requesting more information about something mentioned in a recent column. I also received a phone call from a reader describing a bad encounter with a certain common plant. She wanted to share her experience so it didn’t wouldn’t happen to anybody else. And a conversation about how bad the poison oak is this year triggered a discussion about how to dispose of the stuff. So here goes. All the news that’s fit to print.
Whether it was Joe Friday who said it or Dan Akroyd in the Dragnet parody. we all want “Just the Facts, Ma’am“.
In my column a couple weeks ago about garden planning for the drought, it was the last line “And don’t forget the… mulch (no shredded bark, please)” that caused a bit of confusion. It’s great that everyone has accepted the value of covering the soil with organic mulch. Organic mulches- such as bark chips, treated sawdust, straw or even grass clippings- keep plant roots cool, encourage earthworms and other beneficial organisms, conserve soil moisture, combat weed growth and protect the soil from erosion.
But is there an organic mulch that is better than another?
There are many types of mulch available. Nurseries sell different types of mulch in bags, building supply yards carry everything from bark nuggets in different sizes to treated sawdust to chipped bark and even shredded redwood bark. It’s the shredded redwood bark, also called gorilla hair, that does nothing for the health of your soil. If you have a very steep slope you may have to go with this type of mulch but that’s the only time I can recommend it. It will cling to a hillside without washing down in winter rains but treated sawdust would also work for this type of terrain and is much better for soil health.
Of all the types of organic mulches out there, recent studies have shown that ramial bark chips are one of the best mulches to improve soil health. Ramial chips come from trees and brush with branches up to about 3” in diameter with or without leaves. These chips contain a high percentage of thin young bark and young wood. This is what makes them so valuable to the garden. Young wood is a tree’s factory for producing protein, glucose, fructose, lignin and polysaccharides. It’s an important source of nutrients for living things at all levels according to a study by soil scientists, G.Lemieux and R.A.Lapointe. You can obtain these kind of chips free from tree trimming companies who are probably working nearby chipping roadside brush for PG&E.
About that call from a reader who had a terrible experience after pulling some plants in her yard that had gotten a little out of hand. She said she and her husband ended up with severe eye burn after getting some toxic sap from euphorbia in them. She said they really don’t know if some of sap became airborne while they were pulling stems or if they accidentally rubbed some near their eyes at some point in the day. They went to Urgent Care right away for treatment but the pain lasted for days. She described it as one of the most painful experiences she has ever had. Euphorbias are very deer resistant and drought tolerant and are being used more and more in gardens.
Many of us, me included, grow tropical milkweed or Asclepias curassavica to attract monarch butterflies. The milky sap from this plant protects the monarch from being eaten and can cause the same painful burning of the eye. I read of a case where a gardener’s clothes brushed some stems while she was tending the garden. Later she wiped the sweat out of her eyes and didn’t realize she had also touched her pants. She ended up with cornea burn causing temporary blindness and had to take strong pain relievers and steroids to elevate the pain.
Lastly, a fine crop of poison oak is growing this year so thick in places you can barely avoid it. The new foliage literally glistens with toxic oils. Many birds relish the white berries that form later in the season. 9 out of 10 people will get a rash if even one drop of urushiol oil touches the skin. And this oil has lasting power. It can stay active on any surface, including dead plants, for up to 5 years. Burning dead or dormant poison oak branches is especially dangerous as urushiol oils released in smoke can produce disastrous results if inhaled. So what to do with the stuff if you pull it out? Do not put it in your green waste can. It can end up being ground into mulch along with other green waste. Instead put it in your gray garbage can. Other plant matter that has to be put in the garbage can is pampas grass and bamboo. Don’t put them into green waste
So that’s the skinny on shredded redwood or gorilla hair, common plants with toxic sap and poison oak disposal. Be careful out there.