Q. I thought Natal Plum was frost-tender, but I’ve seen it survive several winters where frost occurs regularly. Is there a secret trick to get them to survive the cold?
Natal plum (Carissa macrocarpa) is an attractive shrub bearing jasmine-scented white flowers followed by small, dark-red plum-like fruit. Its leaves are dark green, round, and thick with a waxy surface. It’s a popular hedge plant in frost-free areas like San Diego, Los Angeles, and Orange County because it’s attractive all year round. It’s also surprisingly tolerant of salt spray, so it can thrive close to the beach where most plants would shrivel up and die.
They are usually not frost-tolerant, but if your area only gets mild frost (mid-20s) you might be able to grow Natal plum. Plant them near a sidewalk, south-facing wall, under eaves, or other sheltered location. All these locations offer at least several degrees of frost protection which, in many cases, will be just enough to keep these plants alive.
If any tender plant has been damaged by frost, wait to remove the damaged foliage since those dead leaves can protect the interior of the plant. Once the last frost date for your area has passed, you can clip away. Even if a tree or shrub has been completely defoliated (lost all its leaves), don’t give up hope. Just trim the dead stuff away and water as usual. Many times it will come back to life
Q. My dog likes to eat the yellow flowers off the weeds near our house. I believe the plant is wild mustard. Is this safe?
If he’s eating wild mustard flowers, he should be fine. These plants are closely related to cabbage, broccoli, and cauliflower. Unfortunately, they can produce some horrific gas so you may want to discourage him from eating them. Trust me, I’ve learned this the hard way.
Q. What causes lettuce to become so bitter after it’s flowered? I’ve tried cutting the flower stalk off, but that doesn’t help.
Lettuce will bolt after the weather warms up, or daylight hours increase, or simply because it’s old and had enough. Usually, the head will elongate and start to look like one of the Coneheads from Saturday Night Live (now I’m dating myself). Soon, a flower stalk emerges from the center of the head and quickly grows tall. This is when the plant has decided it’s time to reproduce, so all the sugars that were contained in the lettuce leaves have migrated to the flower head to provide energy for seed production. If you let the flowers mature and produce seeds, you can collect those seeds and use them for next year’s garden.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; 951-955-0170; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu