WateringTimesWatering plan, $19
Vinca major, WUCOLS IV

How often to water bigleaf periwinkle in California

In July in the Central Valley, established bigleaf periwinkle 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. Bigleaf periwinkle is an evergreen groundcover with glossy, heart-based leaves and blue-violet flowers in spring, often repeating into fall. Its trailing stems root wherever they touch soil, forming a dense mat that spreads fast. It has escaped gardens across much of California, invading streamsides and woodlands, so it needs firm containment if grown at all.

Ground coverPerennialRated for 4 of 6 zones

How often to water bigleaf 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 bigleaf 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 that bigleaf periwinkle needs water, especially in sun
  • Leaves wilting and turning dull in hot afternoon sun can indicate a dry root zone
  • Yellowing leaves and blackened stems in soil that stays soggy can indicate root rot
  • Spotted leaves or blighted stem tips point to leaf spot or blight rather than thirst
  • New plants appearing well beyond the bed show stems rooting or washing away, not a need for water

How to water it

  • Water the soil beneath the mat with a soaker line, keeping runoff from carrying stem pieces away
  • Moisten the top 6 inches of soil, then let the surface dry before the next watering
  • Plant only in a contained bed with deep edging, far from creeks, drainage channels and wild land
  • Give it partial shade and fertile, well-drained soil, where it dries out more slowly than in full sun
  • Pull stems that root past the edging, and never dump clippings where water can carry them

Through the seasons

Keep new plantings moist until they root. After that, established mats take deeper, less frequent watering. Bloom comes mainly in spring, with scattered flowers into fall, and the evergreen foliage carries on through winter. WUCOLS rates bigleaf periwinkle low water in the Central Valley. It rates moderate water in South Inland, the high desert and the low desert. WUCOLS marks it as not suited to the north-central coast or the south coast. It is invasive in California, and its use in urban landscapes is strongly discouraged.

In pots

A container is the safest way to grow bigleaf periwinkle, since the pot keeps its rooting stems in check. Use a pot with drainage holes and a fertile, well-drained mix. Check the mix an inch or two down every few days in summer and water when it is dry. Water until excess drains, then empty the saucer. Trim trailing stems before they touch the ground, and bag the clippings. In winter, water only when the mix dries.

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

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan–0.16–0.780.740.78
Feb–0.26–0.870.930.93
Mar–0.43–1.31.461.52
Apr–0.61–1.611.891.95
May–0.83–1.952.392.45
Jun–0.99–2.292.852.79
Jul–1.07–2.513.042.85
Aug–0.95–2.332.792.6
Sep–0.72–1.862.142.08
Oct–0.47–1.331.461.49
Nov–0.22–0.90.930.96
Dec–0.14–0.680.650.68
Year–6.84–18.4121.2721.08

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

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 bigleaf 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 bigleaf periwinkle in summer?

In July, established bigleaf periwinkle in loam needs a deep watering about every 20 days in the Central Valley 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 bigleaf periwinkle need per day?

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

Yes. WUCOLS rates bigleaf periwinkle separately for each of the six California climate zones: not suited to this region in the North-Central Coastal zone, low water in the Central Valley zone, not suited to this region 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 bigleaf periwinkle invasive in California?

Yes. It has escaped gardens and spreads in coastal counties, foothill woodlands, the Central Valley and even desert areas, crowding out native plants. Streamsides are especially vulnerable, because broken stems wash downstream and root.

Does periwinkle carry a grape disease?

Yes. It is a known host of the bacterium that causes Pierce's disease, which is deadly to grapevines. Keep it away from vineyards and backyard grapes.

How do I get rid of bigleaf periwinkle?

Pull or dig out the stems along with their rooted nodes, removing every piece you can. Bag the debris rather than composting it near water. Check back often, since missed fragments can start new plants.

Can you overwater bigleaf periwinkle?

Yes. It prefers moist soil with good drainage, and ground that stays soggy can bring root rot. Let the surface dry between waterings.

How is bigleaf periwinkle different from small periwinkle?

Bigleaf periwinkle has larger flowers and thinner leaves with heart-shaped bases and fine hairs along the edges. Small periwinkle has thicker leaves without those hairs. Both spread by rooting stems.

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Sources