Houseplant 101: What you need to know about keeping your indoor garden healthy

Q. How do I keep my houseplants looking good? They always look nice right after I bring them home, but soon after the leaves start turning brown at the tips.

Most houseplants are tropical, so they thrive in full, but indirect, sun and high humidity.  If they don’t get enough sun, they will stop growing. When they aren’t growing, they don’t take up much water. At this point, when you water the roots end up sitting in soggy soil and will rot. Root rot (from overwatering) is the most common cause of death for indoor plants. Giving them 5 or 6 hours per day of indirect light will keep them growing and happy. Don’t place them in full, direct sun because an indoor plant is not acclimated to intense sunlight and will burn quickly.  A spot that is within 3 or 4 feet of a south or west-facing window should provide adequate sunlight. 

Humidity (or lack of it) is a common problem for houseplants in our dry Southern California climate. Brown leaf tips/edges can be a sign of inadequate humidity. Calatheas are especially prone to leaf tip browning. Periodic misting with water can be helpful but may be inadequate. I recommend using distilled water for this since it will leave no hard water deposits. To increase local humidity, group plants together or use a pebble tray (a shallow tray or saucer containing gravel and filled to the top of the gravel with water). Set the pot on top of the water or just leave the tray nearby so the evaporating water can increase the local humidity. I will use several smaller saucers for pebble trays and place them between the pots. (Only because I have a lot of them sitting around.) When the air becomes especially dry (during a Santa Ana, for instance), use a cool mist humidifier to make the air more comfortable for both you and your plants. 

Q. Is it safe to use vinegar to kill weeds? What about salt?

The internet is full of gardening advice but unfortunately, most of it is really bad. Vinegar can be used as a weed killer, but I would only use it on weeds growing between pavers or sidewalk cracks since it can damage non-target plants. If we didn’t all live in a fire-prone area, those propane-powered flame-thrower things look like they’d be satisfying to use, especially on nutgrass and some other stubborn weeds. Unfortunately, that’s not a good choice for Southern California since you’d risk setting the state on fire.

Salt is a very bad idea for weed killing, even if used on sidewalk cracks or between pavers. Sure, the salt will kill the weeds, but it will remain in the soil and kill any other plants that are nearby. If you try to wash the salt away, it will kill any plants exposed to the runoff. Do not use salt as a weedkiller!

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; https://ucanr.edu/sites/RiversideMG/

San Bernardino County

mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu