Fighting frost and fungus: 5 things to do in the garden this week

1. Each evening, listen to the weather forecast and take the necessary protective measures where frost, when the temperature dips below 32 degrees, is predicted. From now until mid-March, frosty nights are a possibility in Southern California. Tropicals are most susceptible to frost damage but so are species of any description planted within the last six months. To prevent cold damage, cover plants with old drapes, blankets, sheets, or spun polypropylene floating row cover (the GardenQuilt brand provides protection down to 24 degrees) when frost is predicted; make sure to remove such coverings in the morning. Wrap trunks of citrus and avocado trees with burlap. Another cold protection strategy is to string holiday lights around frost-sensitive plants. Overhead irrigation on nights when frost is forecast will also prevent cold damage. As water freezes to ice, heat is released. As long as ice is kept wet, its temperature will not dip below 32 degrees and thus even ice-covered plants will not be damaged. You can tell if plants are being frost-protected if water drips from ice that has formed. If water applied simply results in thicker ice, the rate of water application needs to be increased until dripping is observed. By the way, the word “hardy”, horticulturally speaking, refers to plants’ ability to withstand cold temperatures.

2. Peach leaf curl, which affects both peaches and nectarines, is a devastating fungus disease. It appears on new leaves, which pucker and curl, in the spring but applying a copper spray prevents the pathogenic fungus, Taphrina deformans, from developing. Two annual sprayings are recommended: immediately after Thanksgiving and just before Valentine’s Day. Liqui-Cop by Monterey is promoted specifically for its use in stopping peach leaf curl. Common wisdom on this subject holds that once a tree exhibits peach leaf curl, typically soon after leaves appear in the spring, nothing can be done to interrupt its spread until leaves drop in the fall and spraying can be done as a measure to protect next year’s growth from contracting the disease. However, some success has been achieved by application of a garlic and citrus spray after leaves become infected with the fungus. The product is known as Garlic Barrier AG+ and is promoted primarily as an insect repellent, deterring ants, aphids, beetles, grasshoppers, leafhoppers, leafminers, loopers, mealybugs, mites, and whiteflies. According to the manufacturer, “the citric acid damages many insects’ outer coating (cuticle) and the garlic oil suffocates them by clogging their breathing holes (spiracles).” This product, which needs to be applied weekly, is also supposed to work systemically – protecting all plant parts after application to the foliage. Garlic Barriet AG+ also discourages birds, deer, and rabbits from chomping on your plants. 

3. Although there are 250 camellia species, only two of them are locally grown: Camellia japonica, which starts blooming in midwinter, and Camellia sasanqua which blooms mostly in the fall. What sasanquas lack in flower size as compared to their japonica cousins, they make up for in profusion of blooms, which appear in white and every version of pink and red. Sasanqua flowers are mildly fragrant, too. While camellias may seem exotic or challenging to the novice gardener, they are actually among the easiest woody plants to grow. They do best protected from afternoon sun, with a partial sun or light shade exposure being ideal. Yet the larger a camellia becomes, the more sun it can take since its leafy growth does a good job of shading the soil below so water is not lost through evaporation and roots stay cool. While you would not designate camellias as drought tolerant, an established camellia that is well-mulched can subsist on a single soaking per week in hot weather if not less. The world’s outstanding camellia collection is found at Descanso Gardens in La Canada. Viewing camellias there is best done in February when the japonicas are in bloom and many of the sasanquas are still be flowering. The nursery of choice where camellias are concerned is Nuncio’s (nucciosnurseries.com). It’s located at 3555 Chaney Trail in Altadena. It’s open 8 a.m. to 4.:30 p.m. Friday-Tuesday.

Related Articles

4. Cyclamen is the Rolls Royce of the fall and winter flower bed. A cyclamen growing in a four-inch pot is likely to cost considerably more than a similarly sized snapdragon, pansy, or primrose. Yet, if you are careful, you can keep a cyclamen plant alive for decades so that it will more than justify its higher price. Cyclamen should get a half day of sun at least and be planted in fast-draining soil. As is the case with daffodils, the secret to keeping cyclamens alive is a complete absence of water once they go dormant after flowers fade in early spring and leaves shrivel. To be safe, lift cyclamen tubers when the plants enter dormancy and store them in a paper bag in a cool place such as a garage. Cyclamen has silky petals that sweep upward in red, pink, mauve, or white, with distinctive V-shaped markings on its heart-shaped leaves. Dwarf varieties are also available.

5. Plant nasturtium seeds now, one inch deep and 10 inches apart, in fast-draining soil. If you want to get kids interested in gardening, planting nasturtium seeds is a great way to do it. Their large size – they resemble garbanzo beans – make them easy to handle. All parts of nasturtium (Tropaeolum majus) are edible, with a peppery taste that will remind you of watercress. Flowers are a popular garnish for salads. Nasturtium are famous for naturalizing an area through self-sowing where soil is to their liking and they receive about half of the day’s sun. A large expanse of nasturtium requires minimal watering due to floppy foliage which completely blocks the sun from reaching the soil. Nasturtium grows effortlessly, even for neglectful gardeners, which is how the expression “Be nasty to nasturtium” came about. There are two available types: those that vine up to six feet or trail along the ground and those that grow into bushes that are one and a half feet tall and wide. Their classic flower colors are orange and yellow, but you can also find nasturtiums in red, salmon, purple, and maroon, as well as double-flowered varieties. There are also variegated nasturtiums with leaves that are mottled green and white.

Please send questions, comments, and photos to joshua@perfectplants.com