WateringTimesWatering plan, $19
Cotoneaster horizontalis, WUCOLS IV

How often to water rock cotoneaster in California

In July in the Central Valley, established rock cotoneaster in loam needs a deep watering about every 20 days: about 2.2 gallons each time for a plant 2 feet across, about 0.8 gallons a week. Rock cotoneaster is a slow, low shrub 2 to 3 feet tall that spreads 6 feet or more. Its stiff, flat branches are arranged like a fishbone. Small pink spring flowers give way to bright red berries, and in cool areas the leaves turn red-orange in fall. It tolerates poor soil and becomes drought tolerant, though it prefers cooler summers.

Ground coverRated for 5 of 6 zones

How often to water rock cotoneaster, month by month

Your city
Plant width
2 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 rock cotoneaster 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

  • Soil dry 4 inches down under the branches in summer signals rock cotoneaster can take a soak
  • Small leaves dulling and dropping in a long hot spell can indicate drought stress
  • Fine speckling and webbing on leaves in hot, dry spots point to spider mites
  • Blackened, scorched-looking shoot tips point to fireblight, not a lack of water

How to water it

  • Water under the spreading branches with low drip or a soaker
  • Soak several inches down, then let the soil dry before watering again
  • Plant in full sun to part shade in loose, well-drained soil
  • Let it drape over walls, rocks or slopes where water drains away
  • Pull seedlings that come up from dropped berries

Through the seasons

Water a new planting regularly through its first summer as branches spread. Established shrubs are drought tolerant and need only occasional deep soaks. In warm areas it stays semi-evergreen, while in colder spots it drops its leaves after fall color. Berries ripen red in fall. WUCOLS rates rock cotoneaster low water on the north-central coast, in the Central Valley and on the south coast. South Inland and the high desert carry a moderate water rating. WUCOLS marks it as not suited to the low desert.

In pots

Rock cotoneaster can spill over the edge of a large, low container or raised planter. Use well-drained mix. Water when the top couple of inches are dry, letting water run out freely. In summer sun, check every few days. Empty the saucer. Rinse dust from the leaves in hot weather to discourage mites. In winter, rain is often enough, so feel the mix first.

1 Your climate zone six WUCOLS zones, each from its own reference city
1.07gal per sq ft in JulyLow water use in the Central Valley zone
A year
6.84 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.761.52.33.00.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.761.52.33.00.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Rock Cotoneaster: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.780.74–
Feb0.210.260.320.870.93–
Mar0.350.430.461.31.46–
Apr0.470.610.561.611.89–
May0.580.830.641.952.39–
Jun0.640.990.692.292.85–
Jul0.641.070.792.513.04–
Aug0.60.950.742.332.79–
Sep0.50.720.61.862.14–
Oct0.350.470.461.331.46–
Nov0.190.220.330.90.93–
Dec0.120.140.260.680.65–
Year4.86.846.218.4121.27–

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 low water in the Central Valley, like rock cotoneaster. Plants that drink alike can share one valve and one schedule.

BougainvilleaBougainvillea & spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyLantanaLantana camara ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyJunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyYarrowAchillea millefolium (non-native hybrids)low water, Central Valley1.07 gal/sq ft in JulySagebrushArtemisia spp. (shrubby)low water, Central Valley1.07 gal/sq ft in JulyCalifornia Native YarrowAchillea millefolium (CA native cultivars)low water, Central Valley1.07 gal/sq ft in JulyWoolly YarrowAchillea tomentosalow water, Central Valley1.07 gal/sq ft in JulyGround Morning GloryConvolvulus mauritanicuslow water, Central Valley1.07 gal/sq ft in JulySouth African GeraniumPelargonium sidoideslow water, Central Valley1.07 gal/sq ft in JulyLippia GroundcoverPhyla nodiflora (Lippia nodiflora) cvs.low water, Central Valley1.07 gal/sq ft in JulyRock SoapwortSaponaria ocymoideslow water, Central Valley1.07 gal/sq ft in JulyMother of ThymeThymus praecoxlow water, Central Valley1.07 gal/sq ft in JulyVancouver Jade BearberryArctostaphylos uva-ursi 'Vancouver Jade'low water, Central Valley1.07 gal/sq ft in JulyTrailing LantanaLantana montevidensis (sellowiana) ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyGermanderTeucrium chamaedrys ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyBigleaf PeriwinkleVinca majorlow water, Central Valley1.07 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 rock cotoneaster, 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 often should I water rock cotoneaster in summer?

In July, established rock cotoneaster in loam needs a deep watering about every 20 days in the Central Valley, about every 27 days on the south coast and about every 9 days in the South Inland zone. Sandy soil holds less water, so waterings come closer together. Clay stretches them. Check the soil before each watering and skip one after a soaking rain.

How much water does rock cotoneaster need per day?

In July in the Central Valley, established rock cotoneaster needs about 0.1 gallons a day for a plant 2 feet across and about 0.4 gallons a day for a plant 4 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 rock cotoneaster change across California?

Yes. WUCOLS rates rock cotoneaster separately for each of the six California climate zones: low water in the North-Central Coastal zone, low water in the Central Valley zone, low water in the South Coastal zone, moderate water in the South Inland zone, moderate water 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.

Are rock cotoneaster berries poisonous?

If eaten, the fruits can cause stomach upset. Keep children from eating them. Birds eat them and spread seed.

Why does my cotoneaster have black, burned-looking tips?

That is likely fireblight, a bacterial disease. Prune out affected shoots well below the damage and clean tools between cuts. It is not a sign of thirst.

Does rock cotoneaster need much heat?

No, it prefers cooler temperatures and may struggle in very hot summers. Mites also increase in hot, dry spots.

Can I train rock cotoneaster on a wall?

Yes, its flat, fishbone branches can be trained on rock walls, trellises or fences. It also covers slopes well. Water at the base of the wall.

Is rock cotoneaster evergreen?

It is semi-evergreen in warm areas and deciduous in colder ones. Deciduous plants color red-orange first. The branch pattern gives winter interest either way.

More plant watering guides

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Sources