Q: Last year I bought potted herbs and repotted them in larger containers under a heat light. They were successful, but I was plagued by fruit flies to the point I gave up. I used milk and vinegar/soap solutions, but to no avail. I want to give it another shot and any help you can give me regarding soil and fly protection would be appreciated.
Bob, Burnaby
A: These flies are similar to fruit flies, but when they come from potted plants they are fungus gnats. The type of soil is no problem, but the moisture content is. Fungus gnats live and breed in moist soil. In dryer soil, they don’t breed and so die out.
The best solution I’ve found is spreading about a third to a half-inch (1 cm) deep layer of sand over the surface of the potting mix where the plants are growing. Then let the soil dry out just a little before watering again. Some people deal with fungus gnats by watering from the bottom and a few hours later dumping the water and waiting a few days before watering again. Another alternative is dusting cinnamon powder over the soil surface.
Many Mediterranean herbs prefer soil that dries out periodically because well-drained soil and occasional droughts are the type of situation they’re used to in the lands from where they originate. Rosemary, thyme, sage and oregano are all Mediterranean herbs.
Parsley does best in fertile soil, but can handle dryness because it has a taproot where it can store food and moisture. Chives have storage in their bulbs.
Mint does better in moist soil, but prefers to be outside if you can manage it. Fungus gnats don’t survive long outside because pests of all kind are a free lunch for birds.
Q: My bay tree was damaged by cold temperatures last winter when I left it outside. I usually put it into my tool shed. Do you know the hardiness of this plant for our wet, cold winters?
Judith MacDonald, Vancouver
A: Your bay tree is a Mediterranean native. It’s a Zone 8 tree reputed to be hardy to 5 F (15 C), but this is in perfect conditions — warm south wall, excellent drainage.
This means that on the Gulf Islands, on Vancouver Island, on very sheltered south slopes and in Vancouver areas close to the sea, garden-planted bay trees usually survive. But even then they’re always susceptible to colder than normal temperatures or unusually chilly winds especially when cold combines with wet. So in our present climate their winter survival outside is always a gamble.
Since you put your bay tree in a shed overnight during winter, it’s probably in a container. Container plants need to be one zone hardier than those planted in gardens where their roots are sheltered in earth. Whenever temperatures dip below freezing, your bay tree should be in your shed day and night – hopefully by a window.
Don’t be surprised if it defoliates. This is a response to sudden, stressful changes. Lemon trees do the same thing. Bay trees almost invariably leaf out again in spring.
Anne Marrison is happy to answer garden questions. Send them to her via amarrison@shaw.ca. It helps if you mention your city or region.
amarrison@shaw.ca
