Mexican Rush

Year-round

Mexican rush is a clumping, grass-like plant that actually grows wild in San Francisco, at the Presidio, and it does best where the soil stays damp with full sun to partial shade.

• Keep the soil consistently moist. This plant does not like drying out, especially through summer.
• Give it full sun to partial shade. It handles San Francisco fog and mild coastal light well.
• Plant it where water collects, like a rain garden, pond edge, or bioswale, not a typical dry flower bed.
• It is native to the San Francisco area, documented growing wild at the Presidio, so it fits a native, habitat focused planting here.
• This species does not appear on the ASPCA toxic plant list for cats or dogs, though it is not on their confirmed non-toxic list either, so keep an eye on pets who chew on any grass-like plant.

Fall

Fall is when San Francisco's rains return, so you can ease off watering, and it is a good time to tidy up the clump before winter.

• Ease up on extra watering once the fall rains start, usually by November.
• Cut back any dead or flopped over blades to keep the clump looking neat and upright.
• This is a good time to plant new divisions, since cooler, wetter weather helps new roots settle in before summer.
• Clear fallen leaves out of the clump so the base does not stay soggy and matted under debris.

A tidy fall cutback like this reads as an intentional garden bed instead of a spreading weed patch, which is exactly the impression that heads off an HOA letter.

Winter

Winter is San Francisco's wet season, so Mexican rush gets plenty of natural water on its own, and the main job is just keeping an eye on drainage and the rare cold night.

• Let the winter rains do the watering. This plant is built for wet soil this time of year.
• San Francisco rarely gets frost, but on the occasional cold night in December or January, a light frost will not seriously harm an established rush like this one.
• Make sure water is not pooling so deep or long that it drowns nearby plants. This rush tolerates standing water better than most companions.
• Keep the clump cut back and tidy through winter dormancy.

Trimmed, tidy dormant clumps avoid the neglected-yard look that sometimes draws an HOA letter during winter curb checks.

Spring

Spring is when Mexican rush puts out fresh growth as San Francisco's rainy season winds down, making it the best time to divide crowded clumps or plant new ones.

• Divide overgrown clumps in March or April, right as the rains ease up, and replant divisions with room to grow.
• Keep watering by hand if a dry spell hits in April or May, since the rain that kept it moist all winter is tapering off.
• Watch for new shoots spreading past where you planted it. That is normal for this plant, but cut them back or add a barrier if it is heading somewhere you do not want it.
• Skip fertilizer. Wetland plants like this one generally do fine on their own in damp soil.

Keeping the spread contained in spring is what keeps this rush looking like a deliberate garden feature instead of a creeping weed, which is the detail an HOA letter usually flags.

Summer

Summer is San Francisco's dry season, so this is the time of year Mexican rush needs the most watering attention to avoid drying out.

• Water regularly. This plant wants consistently moist soil, and San Francisco's summer fog does not replace real rainfall.
• If it is planted at a pond edge or bioswale, check that the water source, whether a drip line, greywater, or standing water, is still reaching it during the dry months.
• Light afternoon shade or the city's typical summer fog cover is fine. This plant does not need full blasting sun to do well.
• Trim off any completely brown, dried out blades so the clump does not look stressed.