WateringTimesWatering plan, $19
Vinca minor, WUCOLS IV

How often to water periwinkle in California

In July in the Central Valley, established periwinkle 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. Periwinkle, Vinca minor, is a trailing evergreen groundcover that forms a dense mat of glossy leaves topped with blue-violet flowers in spring. It tolerates dry shade once established but still needs regular checks while a new planting knits together. This plant is not the taller, warm-season Madagascar periwinkle sold as a bedding annual.

Ground coverPerennialRated for 6 of 6 zones

How often to water periwinkle, 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 periwinkle 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 an inch or two down beneath the mat signals an established periwinkle patch needs water
  • Dull or curled periwinkle leaves warrant checking moisture beneath the mat before adding irrigation
  • Yellowing, collapsing periwinkle over saturated soil calls for checking drainage and inspecting the stems
  • Bare patches in periwinkle need inspection for damaged stems as well as a root-area moisture check
  • Vigorous runners rooting well beyond the bed reflect normal spread, not a cue about watering

How to water it

  • Water newly planted periwinkle plugs often enough to keep the root zone from drying out completely
  • Check an established mat an inch or two down and water when that layer is dry
  • Use overhead sprays or drip under shrubs and trees where periwinkle is commonly used as a groundcover
  • Mulch lightly around a new planting while leaving the center of each plug uncovered
  • Pull or trim runners that root past the bed's edge instead of cutting back on water to slow them

Through the seasons

Keep a newly planted periwinkle bed evenly moist through its first summer while runners root and knit the mat together. Established plantings tolerate short dry spells but still perform best with periodic soil checks through the warm season. This groundcover stays evergreen year round and keeps using some water even in mild winters. WUCOLS rates periwinkle moderate water in all six climate zones, from the coast and Central Valley through South Inland and both deserts. Winter rain can cover part of the cool season on the coast and in the Central Valley, while desert plantings need regular checks through dry winter stretches as well.

In pots

If keeping periwinkle in a container, watch its trailing stems for contact with nearby soil. Check the top inch of mix often in summer heat, since a shallow pot dries faster than a garden bed. Water until it drains through the holes, then empty the saucer so roots do not sit wet. Trim trailing stems that root into neighboring pots or the ground below. In winter, water less often as growth slows, keeping the mix from drying out 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
0.761.52.33.00.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.761.52.33.00.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.780.780.740.78
Feb0.530.650.810.870.930.93
Mar0.871.091.151.31.461.52
Apr1.181.521.41.611.891.95
May1.462.081.611.952.392.45
Jun1.612.481.742.292.852.79
Jul1.612.671.982.513.042.85
Aug1.492.391.862.332.792.6
Sep1.241.81.491.862.142.08
Oct0.871.181.151.331.461.49
Nov0.470.560.840.90.930.96
Dec0.310.340.650.680.650.68
Year1217.1115.518.4121.2721.08

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 periwinkle. Plants that drink alike can share one valve and one schedule.

DahliasDahlia spp.moderate 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 JulyFernsNephrolepis cordifolia (SHADE IN DESERT)moderate water, Central Valley2.67 gal/sq ft in JulyDayliliesHemerocallis spp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBegoniasBegonia & ssp. & cvs. (shade in the desert)moderate water, Central Valley2.67 gal/sq ft in JulyIvyHedera helixmoderate water, Central Valley2.67 gal/sq ft in JulyCalla LiliesZantedeschia aethiopica SHADE IN DESERTmoderate 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 JulySageSalvia officinalis and cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBicolor MonkshoodAconitum cammarummoderate water, Central Valley2.67 gal/sq ft in JulyGarden MonkshoodAconitum napellusmoderate water, Central Valley2.67 gal/sq ft in JulyCarpet BugleAjuga reptans (shade)moderate water, Central Valley2.67 gal/sq ft in JulySnowdrop WindflowerAnemone sylvestrismoderate water, Central Valley2.67 gal/sq ft in JulyGreen Supreme ManzanitaArctostaphylos uva-ursi 'Green Supreme'moderate water, Central Valley2.67 gal/sq ft in JulyMassachusetts ManzanitaArctostaphylos uva-ursi 'Massachusetts'moderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

Rated lower than periwinkle 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 JulyAgapanthusAgapanthus orientalislow water, Central Valley1.07 gal/sq ft in JulyGeraniumsPelargonium x hortorum and cvs.low water, Central Valley1.07 gal/sq ft in JulyLantanaLantana camara ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySalviaSalvia greggii ssp., cvs. & hybridslow water, Central Valley1.07 gal/sq ft in JulyIrisesIris germanicalow water, Central Valley1.07 gal/sq ft in JulySucculentsEcheveria spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyJunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyRussian SagePerovskia 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 JulyMountain AlyssumAlyssum montanumlow water, Central Valley1.07 gal/sq ft in JulySagebrushArtemisia spp. (shrubby)low water, Central Valley1.07 gal/sq ft in JulySilver SageSalvia argentealow water, Central Valley1.07 gal/sq ft in JulyPurple MulleinVerbascum phoeniceumlow water, Central Valley1.07 gal/sq ft in JulySilvery YarrowAchillea clavennaelow water, Central Valley1.07 gal/sq ft in JulyFern Leaf YarrowAchillea filipendulinalow 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 periwinkle, 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 periwinkle in summer?

In July, established periwinkle 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 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 periwinkle need per day?

In July in the Central Valley, established periwinkle 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 periwinkle change across California?

Yes. WUCOLS rates periwinkle 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, moderate 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.

Is periwinkle the same plant as Madagascar periwinkle?

No. Vinca minor is a trailing evergreen groundcover, while Madagascar periwinkle, Catharanthus roseus, is an upright warm-season bedding plant. They have different care and watering needs, so confirm which one you have before following this guide.

How do I stop periwinkle from spreading into the lawn?

Install a physical edge or barrier between the bed and turf, since runners root wherever they touch soil. Pull or cut back stems that cross the line regularly. Reducing water will not reliably contain its spread.

Does periwinkle need shade to survive?

Periwinkle accepts full sun, partial shade and dappled light, and it also tolerates heavy shade. It prefers moist soil with good drainage despite its drought tolerance. Check the soil beneath the leaves when choosing whether to water an exposed planting.

What can kill patches of periwinkle?

Vine stem canker, also called blight, can damage or kill sizeable patches of periwinkle. Inspect dying stems and check soil moisture before changing irrigation. A diagnosis is more useful than repeatedly soaking a patch that remains wet.

Why does my periwinkle look sparse in deep shade?

Periwinkle tolerates substantial shade, so sparse growth does not identify a light or watering problem by itself. Check soil moisture and inspect stems for injury or disease. Consistent moisture cannot be expected to repair every thinning patch.

More plant watering guides

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Sources