WateringTimesWatering plan, $19
Clematis & ssp., hybrids & cvs., WUCOLS IV

How often to water clematis in California

In July in the Central Valley, established clematis in loam needs a deep watering about every 8 days: about 2.2 gallons each time for a plant 2 feet across, about 1.9 gallons a week. Clematis climbs toward the light while its roots need protection from drying ground. Keep the soil evenly moist beneath mulch, with the stems clear of wet material. A vine with limp leaves needs a soil check before more water, since both dry roots and stem trouble can cause collapse.

VineRated for 6 of 6 zones

How often to water clematis, 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 clematis 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 2 to 3 inches down beside a clematis signals that the root zone needs water
  • Limp new leaves with brown margins can accompany dry soil, especially beside a hot wall
  • Buds that shrivel before opening can follow dryness, so check moisture rather than judging by flowers alone
  • Yellow lower leaves and a soft, dark stem base over wet soil can indicate drainage trouble
  • A single stem collapsing while the soil remains moist can indicate clematis wilt rather than thirst

How to water it

  • Water around the clematis crown and outward, moistening soil about 12 to 18 inches deep
  • Use drip or a slow hose at ground level to keep the climbing foliage dry
  • Mulch over the roots while keeping the stems clear, or shade the ground with low perennials
  • Work compost into clay or fast-draining sand before planting and choose a spot where water does not collect
  • Widen the watered circle as the vine matures and check the soil beside heat-reflecting walls

Through the seasons

Keep a new clematis root ball evenly moist through its first summer as roots spread. Established vines still need steady moisture during spring growth and flowering through the warm season. Most garden types lose their leaves and rest in winter, when demand falls. Winter rain can supply coastal and Central Valley plants; check desert soil through dry gaps before irrigating. WUCOLS rates clematis high water in South Inland and moderate water in the other five climate zones.

In pots

A clematis needs a large, deep container with protection from hot sun on the pot itself. Check the top two inches of mix often in California summer heat, and water when they feel dry. Let excess flow from the drainage holes, then empty the saucer. Mulch the surface or shade the container to protect its roots. A bare vine uses little water in winter, but keep checking the mix during rainless spells rather than letting it dry completely.

1 Your climate zone six WUCOLS zones, each from its own reference city
2.67gal per sq ft in JulyModerate water use in the Central Valley zone
A year
17.11 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
1.02.03.04.00.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC1.02.03.04.00.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

Clematis: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.781.240.740.78
Feb0.530.650.811.390.930.93
Mar0.871.091.152.081.461.52
Apr1.181.521.42.581.891.95
May1.462.081.613.122.392.45
Jun1.612.481.743.672.852.79
Jul1.612.671.984.023.042.85
Aug1.492.391.863.722.792.6
Sep1.241.81.492.982.142.08
Oct0.871.181.152.131.461.49
Nov0.470.560.841.440.930.96
Dec0.310.340.651.090.650.68
Year1217.1115.529.4621.2721.08

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 moderate water in the Central Valley, like clematis. Plants that drink alike can share one valve and one schedule.

JasmineJasminum polyanthummoderate 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 JulyGrapevinesVitis vinifera ssp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyEvergreen ClematisClematis armandiimoderate water, Central Valley2.67 gal/sq ft in JulyWinter CreeperEuonymus fortunei radicansmoderate water, Central Valley2.67 gal/sq ft in JulyArabian JasmineJasminum sambacmoderate water, Central Valley2.67 gal/sq ft in JulyHyacinth BeanLablab purpureus (Dolichos lablab)moderate water, Central Valley2.67 gal/sq ft in JulyTrumpet HoneysuckleLonicera sempervirensmoderate water, Central Valley2.67 gal/sq ft in JulyPink Trumpet VinePodranea ricasolianamoderate water, Central Valley2.67 gal/sq ft in JulyPotato VineSolanum laxum (jasminoides)moderate water, Central Valley2.67 gal/sq ft in JulyItalian ClematisClematis viticellamoderate water, Central Valley2.67 gal/sq ft in JulyHopsHumulus lupulusmoderate water, Central Valley2.67 gal/sq ft in JulyBoston IvyParthenocissus tricuspidatamoderate water, Central Valley2.67 gal/sq ft in JulyVirginia CreeperParthenocissus quinquefolia ssp. & cvs.moderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 9

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

BougainvilleaBougainvillea & spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyWisteriaWisteria spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyFlowering WoodbineLonicera periclymenumlow water, Central Valley1.07 gal/sq ft in JulyFleeceflowerFallopia baldschuanica (Polygonum aubertii)low water, Central Valley1.07 gal/sq ft in JulyCarolina JessamineGelsemium sempervirenslow water, Central Valley1.07 gal/sq ft in JulyCecile Brunner RoseRosa 'Cecile Brunner'low water, Central Valley1.07 gal/sq ft in JulyLady Banks RoseRosa banksiaelow water, Central Valley1.07 gal/sq ft in JulyRoger's Red GrapeVitis 'Roger's Red'low water, Central Valley1.07 gal/sq ft in JulyBlue Dawn Morning GloryIpomoea acuminatalow 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 clematis, 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 clematis in summer?

In July, established clematis in loam needs a deep watering about every 8 days in the Central Valley, about every 11 days on the south coast and about every 5 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 clematis need per day?

In July in the Central Valley, established clematis needs about 0.3 gallons a day for a plant 2 feet across and about 1.1 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 clematis change across California?

Yes. WUCOLS rates clematis separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, moderate water in the Central Valley zone, moderate water in the South Coastal zone, high water in the South Inland zone, moderate water in the High and Intermediate Desert zone, moderate water in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

How do I water clematis after planting?

Feel the nursery root ball as well as the ground around it. The ball can dry sooner than the surrounding soil. Expand the soaked area as roots move out instead of leaving the water at one point beside the stem.

What should I do for clematis in a heat wave?

Check beneath the mulch before the hottest weather. If the soil is drying, soak deeply and shade the base from afternoon sun. Leaves that recover by morning do not establish a need for an extra watering.

How deeply should I water clematis?

Aim to moisten soil about 12 to 18 inches deep around established clematis. Beside a wall, check beyond the sheltered root ball as well.

Do clematis need cool roots?

Shade the outside of a clematis container or mulch its surface to protect the roots. Companion plants in the same pot also compete for moisture.

Why did one clematis stem suddenly collapse?

Inspect the collapsed clematis stem for damage or darkened tissue near its base. Cut affected stems back to healthy tissue and keep watering guided by soil moisture.

More plant watering guides

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Sources