They thrive in our area, mostly hiding in cool damp places during the daytime. At night is when they do most of their feeding. Fresh young foliage is one of their favorites, but they go after lots of other things too such as fruit on trees. Strawberries is one of their favorites also. They can crawl up the trunks of trees to get at the fruit, on many plants they go after tasty blooms (Orchids for one). If you let them go unchecked they can destroy almost anything you are trying to grow.
There are a few plants they don't eat, but others they thrive on. The following are suggestions as to how you can control them in your yard or garden. It is generally recommended that the area to be treated should be watered first, so the soil is moist, and then try not to water for about 2 days or longer. Watering the treated are will dilute or wash away some of the product.
The most popular and probably the easiest way, is to use dry Snail and Slug baits. There are many brand names, but generally there are two main ingredients. Iron Phosphate or Metaldehyde. There are a few others, one a liquid containing Cinnamon Oil. In recent years the Iron Phosphate types have been the most popular. Iron Phosphate is considered an 'organic' ingredient and is safer for children and pets. Metaldeyhde is a strong commercial chemical that has been around for many years and was the main ingredient is most Snail and Slug controls. It is still available to gardeners, but you should use caution if you have young children or pets wandering around in your yard. Iron Phosphate and Metaldehyde are most often found in a granular form, which is scattered lightly in areas to kill the snails and keep them off your desirable plants. Lightly scatter the product in and around the plants you are trying to protect. It is also recommended that you apply these products to form a 'barrier' around the main area, especially concentrating on adjacent ground covers such as Ivy or Ice Plant, as they tend to hide there where it is cooler and moist during the daytime. For potted plants, scatter at the base of the container or in the soil where the plants are.
You will probably have to make more than one application of any of them, the first applications will kill the active snails and slugs, but there are eggs that will hatch out and start feeding in a few days or weeks. Generally, apply at about 10 day intervals at first for the heavy populations, then less frequently as the populations die off. Be sure to read and follow the directions on the labels. Metaldehyde can be used in and around food crops but do not get it on any parts of the plants. Iron Phosphate can also be used in and around edible crops, but be sure to wash your harvest thoroughly.
Other ways to help reduce the damage from Snails and Slugs. They do not like copper. You can buy copper bands of thin metal and surround the area you want to keep pest free. This is easier if you have planter boxes or other containers. A thin band, usually between 1" and 2" wide should stop them. If you have problems with fruit trees being infested, you can put the copper band on the trunk of the tree, they will not climb over the band. If you choose this method, be sure the tree is not touching other areas in your yard, like fences or walls. They can crawl up those surfaces to get into the trees. The tree should be 'free standing' and no contact with anything else.
Another way to keep the population down is to put some raised boards in the area. Perhaps 12" x 12" or so, and raised up about 1" to 1.5" above the soil. The Snails and Slugs tend to find dark shady areas, and crawl under the boards. You should check these daily and kill anything under the boards. If you do this on a regular schedule you can greatly reduce their numbers, but it is difficult to get them all. It is safe and fairly effective and the cost is minimal if any.
Another way that is fairly effective and low cost is to go out in the garden at dusk or very early in the morning with a salt shaker. A light 'salting' on any Snail or Slug will kill them. This is also quite safe, no chemicals of any kind, but you need to be persistent and do it almost every day.
Decollate Snails can be effective to kill the Brown Garden Snails, however there are things to be aware of. They may not do a really good job on large mature snails, small to medium size snail are usually what they go after. They love Strawberries! They will also eat small seedlings, so if you are growing plants from seed, this could be a problem. If you choose to go the way of Decollate Snails, you can't use the products mentioned above, it will kill those too. Decollate Snails are best used in orchards and large groundcover areas. CalTrans has been trying them along some of the freeways to reduce the Snail populations there. This is generally considered a slow way to gain control, for best results it is recommended they be used 1 snail to each square foot of area, especially groundcovers. They tend not to 'migrate' very much.
Walter Andersen Nursery has built its reputation on providing the highest quality plant material and the best customer service backed by a professional staff. This, along with the widest variety of plant material available anywhere in San Diego has kept generations of San Diegans coming to Walter Andersen Nursery year after year.Contact them directly at 619 224 8271 (San Diego Store) or 858 513 4900 (Poway Store).