WateringTimesWatering plan, $19
Andromeda polifolia, WUCOLS IV

How often to water bog rosemary in California

In July in the Central Valley, established bog rosemary in loam needs a deep watering about every 5 days: about 8.8 gallons each time for a plant 4 feet across, about 12 gallons a week. Bog rosemary is a low evergreen shrub in the heath family, with narrow blue-green leaves whose edges roll under. Nodding clusters of small pink or white bells open in early summer. It comes from northern bogs and needs acidic, humus-rich soil that stays moist, and heat is its weak point in California gardens.

Ground coverShrubRated for 2 of 6 zones

How often to water bog rosemary, month by month

Your city
Plant width
4 ft
Your soil

Type your city above and the days between waterings and the gallons appear here, worked out from your city's climate table. Or read the figures by climate zone further down.

Every month, on your water days. The personal plan prints this for bog rosemary and the rest of your yard, on the days your water supplier allows.Get the plan for $19

How this is worked out: established roots fill the top 1.5 feet of soil, and you water again when that soil has dried halfway. Loam soil holds about 1.5 inches of water per foot. Water the whole area the plant covers, and skip a watering after a good soaking rain.

Which soil do you have?

Dig down a few inches, take a handful of moist soil and squeeze it.

  • Sandy: gritty, falls apart when you open your hand, will not form a ball.
  • Loam: forms a soft ball that crumbles when you poke it.
  • Clay: forms a firm, sticky ball and squeezes out into a ribbon between thumb and finger.

Still not sure? Pick loam. Most garden beds sit between sand and clay.

How to measure plant width

A shrub with its width marked from one side to the other and the circle under it shaded blue

Measure across the plant, from the tips of the leaves on one side to the tips on the other.

Water the whole area the plant covers, shown in blue. The gallons here cover that area.

A wider plant means more gallons each watering, not more waterings. While it is young, measure again each spring.

How to tell it needs water

  • Dry soil just an inch below the surface around bog rosemary means it needs water right away, since it grows wild in bogs
  • Leaf tips browning or the blue-green foliage dulling in summer can mean the roots have dried or the site is too hot
  • Yellowing leaves with green veins can point to soil that is not acidic enough, which water alone will not fix
  • Wet ground rarely harms this bog shrub, so yellowing over soggy soil more likely comes from heat or alkaline soil than overwatering
  • Stems dying back in patches after a hot spell warrant a check of both soil moisture and afternoon sun

How to water it

  • Water at soil level around the clump with a soaker line, keeping the whole root area moist
  • Keep the top 6 to 8 inches of soil moist, watering again as soon as the surface starts to dry
  • Plant in acidic, lime-free soil rich in peat or leaf mold, in a spot that naturally holds moisture
  • Mulch with shredded bark or pine needles to keep the shallow roots cool and moist
  • Site it in part shade along a pond edge or in a rain garden, where the ground stays damp

Through the seasons

A new bog rosemary needs constantly moist soil through its first year while it roots into the bed. Established plants still need steady moisture all year, as befits a bog native. It stays evergreen and flowers in late spring and early summer. Summer heat is the hardest season, so water and shade matter most from June through September. Winter rain covers the cool months on the north-central coast and in the Central Valley. WUCOLS gives bog rosemary a high water rating on the north-central coast and in the Central Valley. For the south coast, South Inland, the high desert and the low desert, WUCOLS marks it as not suited.

In pots

Bog rosemary grows well in a pot of acidic, peaty mix, which also lets you control its soil. Keep the mix moist at all times, checking it every day or two in summer heat. Water until it runs from the drainage holes. As a bog plant, it can sit over a shallow saucer of water in summer, but tip the saucer out in winter. Shade the pot on hot afternoons, since heat stresses it more than wet roots do.

1 Your climate zone six WUCOLS zones, each from its own reference city
4.27gal per sq ft in JulyHigh water use in the Central Valley zone
A year
27.38 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
1.12.13.24.30.64JAN1.04FEB1.74MAR2.43APR3.32MAY3.97JUN4.27JUL3.82AUG2.88SEP1.88OCT0.89NOV0.55DEC1.12.13.24.30.64JFM2.43AMJ4.27JAS1.88OND
Gallons per square foot per month, Central Valley. Peak 4.27 in Jul, 27.38 a year.

Monthly water need by climate zone

Bog Rosemary: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.60.64––––
Feb0.841.04––––
Mar1.391.74––––
Apr1.882.43––––
May2.333.32––––
Jun2.583.97––––
Jul2.584.27––––
Aug2.383.82––––
Sep1.982.88––––
Oct1.391.88––––
Nov0.740.89––––
Dec0.50.55––––
Year19.227.38––––

How this is worked out: the WUCOLS water rating for each zone times that zone’s climate for the month. A dash means WUCOLS does not rate the plant there. The figures are what the plant uses, before sprinkler losses.

Plants with the same water needs 16

Rated high water in the Central Valley, like bog rosemary. Plants that drink alike can share one valve and one schedule.

HydrangeaHydrangea macrophylla & cvs.high water, Central Valley4.27 gal/sq ft in JulyBlueberriesVaccinium hybrids and cvs (CA native and non- native spp.)high water, Central Valley4.27 gal/sq ft in JulyShell GingerAlpinia zerumbethigh water, Central Valley4.27 gal/sq ft in JulyBlood Twig DogwoodCornus sanguineahigh water, Central Valley4.27 gal/sq ft in JulyRed-veined EnkianthusEnkianthus campanulatushigh water, Central Valley4.27 gal/sq ft in JulyAbyssinian BananaEnsete ventricosumhigh water, Central Valley4.27 gal/sq ft in JulyClimbing HydrangeaHydrangea anomala petiolarishigh water, Central Valley4.27 gal/sq ft in JulySnowball HydrangeaHydrangea arborescenshigh water, Central Valley4.27 gal/sq ft in JulyLacecap HydrangeaHydrangea aspera villosahigh water, Central Valley4.27 gal/sq ft in JulyBrazilian Plume FlowerJusticia carneahigh water, Central Valley4.27 gal/sq ft in JulyBananaMusa spp. (shade in low desert)high water, Central Valley4.27 gal/sq ft in JulyPink KnotweedPersicaria capitata (Shade in San Diego)high water, Central Valley4.27 gal/sq ft in JulyWillowSalix spp. (shrubs)high water, Central Valley4.27 gal/sq ft in JulyBaby's TearsSoleirolia soleirolii (SHADE)high water, Central Valley4.27 gal/sq ft in JulyBellflowerCampanula & spp. and cvs.high water, Central Valley4.27 gal/sq ft in JulyVine MapleAcer circinatumhigh water, Central Valley4.27 gal/sq ft in July

Similar plants that need less water 16

Rated lower than bog rosemary in the Central Valley. Worth a look for a new bed or a lawn replacement.

RosesRosa hybrids..bushmoderate water, Central Valley2.67 gal/sq ft in JulyAzaleasRhododendron spp. (CA native and non-native spp.)moderate water, Central Valley2.67 gal/sq ft in JulyCamelliasCamellia japonica (SHADE IN DESERT)moderate water, Central Valley2.67 gal/sq ft in JulyGardeniasGardenia spp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBird of ParadiseStrelitzia reginae (shade in desert)moderate water, Central Valley2.67 gal/sq ft in JulyHibiscusHibiscus rosa-sinensismoderate water, Central Valley2.67 gal/sq ft in JulySago PalmCycas revolutamoderate water, Central Valley2.67 gal/sq ft in JulyStar JasmineTrachelospermum jasminoides and cvs.moderate water, Central Valley2.67 gal/sq ft in JulyHoneysuckleLonicera japonicamoderate water, Central Valley2.67 gal/sq ft in JulyIvyHedera helixmoderate water, Central Valley2.67 gal/sq ft in JulyArborvitaeThuja occidentalis ssp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBambooBambusa spp.moderate water, Central Valley2.67 gal/sq ft in JulyLilacsSyringa hybrids (including Descanso hybrids)moderate water, Central Valley2.67 gal/sq ft in JulySpireaSpiraea spp. (CA native and non native spp.)moderate water, Central Valley2.67 gal/sq ft in JulyButterfly BushBuddleja davidii and hybridsmoderate water, Central Valley2.67 gal/sq ft in JulyStrawberriesFragaria spp. & cvs. (CA native and non-natives species)moderate water, Central Valley2.67 gal/sq ft in July
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes bog rosemary, your sprinkler type and the month, and gives the minutes per water day for that supplier's schedule. Or put it in a zone of the personal watering plan and get all twelve months printed.

Questions people ask

How much water does bog rosemary need per day?

In July in the Central Valley, established bog rosemary needs about 1.7 gallons a day for a plant 4 feet across and about 6.9 gallons a day for a plant 8 feet across. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Does watering for bog rosemary change across California?

Yes. WUCOLS rates bog rosemary separately for each of the six California climate zones: high water in the North-Central Coastal zone, high water in the Central Valley zone, not suited to this region in the South Coastal zone, not suited to this region in the South Inland zone, not suited to this region in the High and Intermediate Desert zone, not suited to this region in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Can bog rosemary grow in a rain garden?

Yes. It tolerates wet soil and even frequent standing water, so it suits pond margins, stream edges and rain gardens. The soil there still needs to be acidic and rich in organic matter.

Does bog rosemary need acidic soil?

Yes. It is a heath family plant that requires lime-free, acidic soil. In alkaline ground the leaves can yellow even when watering is right, so grow it in a bed or pot of acidic mix.

Can bog rosemary take full sun?

Only where summers stay cool and the soil stays wet. It does poorly in heat, so give it part shade or dappled light in most California gardens. Afternoon shade matters most in the Central Valley.

Is bog rosemary poisonous?

Yes. It is listed as poisonous with medium severity, so keep it away from children and pets that chew plants. Despite the name, it is not related to culinary rosemary.

How big does bog rosemary get?

It grows 8 inches to 3 feet tall and spreads slowly by suckers into a clump. Dwarf forms stay near 18 inches. Widen the watered area as the clump fills in.

More plant watering guides

WillowSteviaDelphiniumCoast RedwoodVariegated Sweet FlagChameleon HouttuyniaBaby's TearsBellflower

Sources