Golden Gate Gardener--Sample Column
Q: I'm a fairly new gardener. I was wondering if there is a way to keep snails out of the garden without spreading poisonous bait. My 18-month-old son likes to "garden," and I obviously don't want him digging amid substances that are harmful.
A: While the brown garden snail may seem a formidable adversary, you can indeed reduce its damage to a minimum while avoiding or rarely using baits. We see ads for snail bait, so we think of it first, but what if we saw ads for other snail-stopping measures?
Learn what snails eat. Snails love hostas and dahlias, but aren't interested in garden penstemon, bidens daisy or crown lychnis. They delight in beans, but usually eschew tomatoes. It is often a minority of plants they love most, and when you see which they are, you can decide whether to grow those plants, or you can use the information to know where to hunt.
Hunt the snails. In the daytime, they congregate in dark, smooth, dry places, whether on leaf undersides or fences behind plants. They come out in force at night, so you can hunt them with a flashlight in hand. If late nights aren't your thing, hunt early on misty mornings. What you do with collected snails is your business, but throwing them into your neighbors yard is rude, and also they can crawl back in a single night. Snail hunts can be remarkably successful in reducing snail populations. If you had started in June, you would have beaten the summer breeding and egg-laying season, but start now, and you will be ahead for next year.
Lay traps for snails. Lay black plastic or a board propped an inch above the ground in a shady place and they will congregate underneath it. But, of course, you have to search frequently, since you have created a snail hotel.
Protect snail predators. Sounds as if you are already avoiding harsh chemicals, so if you lay some mulch or flat stones in shady places, you will probably attract native salamanders and imported rove beetles that will eat snails. Rove beetles are big, velvety black beetles that raise their rears threateningly when disturbed. Raccoons, though pesty in other ways, eat garden snails, and other wild mammals probably do, too.
Bait as a last resort. Snails may be attracted to beer or yeast-baited traps, though mine have not been. A new bait based on iron phosphate in wheat flour is very low in toxicity to humans and other creatures besides snails, and as it breaks down it acts as a fertilizer. (The most common brand name is Sluggo.) It’s in tiny particles, and you spread it so thinly that it is not particularly interesting to children or pets. Indeed, they would have a hard time finding enough of it to harm them. But remember that you don't want to spread it in the middle of a garden, but at the perimeter, to lure snails away. I don't know your garden plan, but there might be difficult-to-search places that are inaccessible to your toddler but accessible to snails where it could be sprinkled to advantage.
Q: We purchased a red-leaf banana plant as an anniversary gift to each other two years ago. It was 4 feet tall. That winter, the deer smashed it down. We cut the damage off, and now it's 15 feet tall and beautiful. We are concerned about its health this winter in the Oakland hills. How can we protect this large plant from the cold?
A: You have chosen an anniversary gift that, planted where it is, is likely, as marriages often are, to suffer some adversity. I will tell you the risks, and then maybe you can choose a few other less risky plants for future anniversary gifts, so that you have sturdier symbols of your love to fall back on in case this one doesn't make it.
I think your plant must be one commonly called red Abyssinian banana (Ensete ventricosum 'Maurelii'). It is a banana relative that doesn't bear tasty fruit but is grown for its dramatic form and its reddish leaves, which are redder when it is grown in full sun.
Like most bananas and related ornamentals, this plant is sensitive to frost. Estimates of the temperatures it can tolerate range from 30 to 20 degrees F. It puts most of the Bay Area in the gambling zone. In any given winter, temperatures might drop too low, or not. Gardeners in borderline climates such as ours often leave the plants unprotected, knowing that bananas damaged by as much as a week of moderate frost may look terrible afterward but will most often recover in summer. If you are very ambitious, you could build a wooden frame and fasten burlap or clear plastic across the top (but not touching the plant) when frost is expected. A string of holiday lights or a couple of small spotlights under the shelter (with proper outdoor cords and outlets) can help keep the temperature a bit higher.
A friend of mine in Chico grew a banana in her garden for many years. The annual few days to a week of freezing winter weather did do some damage, but the tree looked good in summer. This plucky tree was eventually knocked over by a storm, and had to be removed because it was too big to set upright.
Indeed, strong winds are as big a danger to bananas as frost. Sites that protect against both wind and cold include a walled entry, a courtyard or an atrium. The south side of a wall or building will get the most warming sun, and if there is an overhang, this will block falling cold air. On the west side of a building or wall, sun would hit later in the day, allowing the plant to thaw more gradually, but if such a site were exposed to the prevailing western winds, it wouldn't be such a good idea.