WateringTimesWatering plan, $19
Forsythia spp. and hybrids, WUCOLS IV

How often to water forsythia in California

In July in the Central Valley, established forsythia in loam needs a deep watering about every 8 days: about 8.8 gallons each time for a plant 4 feet across, about 7.6 gallons a week. Forsythia is a deciduous shrub in the olive family. Its arching stems carry golden yellow flowers in late winter or early spring, before or as the leaves open. It grows best in full sun with moderate, regular moisture and soil that drains. Once established it rides out a short dry spell, but roots left in saturated ground can die.

ShrubRated for 3 of 6 zones

How often to water forsythia, 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 forsythia 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 3 to 4 inches down beneath the outer stems of an established forsythia means it is ready for a deep soak
  • Leaves that fade in color and stay limp into the next morning over dry soil point to a thirsty root zone
  • Leaf edges and tips turning brown, with leaves dropping early in late summer, can follow a long dry spell
  • Fewer flowers on the bare spring stems can trace back to a dry summer, though pruning after mid-July also removes the buds
  • Leaves that wilt and fade while the soil stays soggy point to roots dying from too much water, not thirst

How to water it

  • Water the soil under the arching branches with drip emitters or a slow hose, keeping spray off the foliage
  • Soak until water reaches a foot or more down, then let the top few inches dry before the next soak
  • Spread wood chip mulch over the root zone, pulled a few inches back from the base of the stems
  • Plant forsythia where water drains away, and build a low mound in heavy clay that holds water after rain
  • Widen the watered ring as the shrub fills out, since border forsythia can spread as wide as 12 feet

Through the seasons

Keep a new forsythia's root ball evenly moist through its first summer, widening the soaked area as roots spread. Established shrubs take deeper soakings with some drying between them. Flowers open on bare stems in late winter or early spring, and the leaves follow. Pruning after mid-July removes next spring's buds, so the summer stems already carry the coming flowers. Leaves drop in fall and the shrub rests through winter, when rain covers the cool months on the coast and in the Central Valley. WUCOLS rates forsythia moderate water on the north-central coast, in the Central Valley and on the south coast. WUCOLS has not evaluated it for South Inland. It marks forsythia as not suited to the high desert or the low desert.

In pots

Full size forsythia grows too wide for most containers, but compact cultivars that stay near 30 inches tall can live in a large pot. Check the mix 2 inches down every few days in summer, and daily during Central Valley heat. Water until it runs from the drainage holes, then empty the saucer so the roots never sit in water. A pot on hot paving dries fast, so shade the container itself. In winter the bare shrub uses little water, so let the mix dry more between soakings.

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
0.671.32.02.70.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.671.32.02.70.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.78–––
Feb0.530.650.81–––
Mar0.871.091.15–––
Apr1.181.521.4–––
May1.462.081.61–––
Jun1.612.481.74–––
Jul1.612.671.98–––
Aug1.492.391.86–––
Sep1.241.81.49–––
Oct0.871.181.15–––
Nov0.470.560.84–––
Dec0.310.340.65–––
Year1217.1115.5–––

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

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 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 JulySageSalvia officinalis and cvs.moderate water, Central Valley2.67 gal/sq ft in JulyRed BuckeyeAesculus paviamoderate water, Central Valley2.67 gal/sq ft in JulyWestern ServiceberryAmelanchier alnifoliamoderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

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

LavenderLavandula spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyRosemaryRosmarinus officinalislow water, Central Valley1.07 gal/sq ft in JulyBougainvilleaBougainvillea & spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyOlive TreesOlea europaea ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyCrape MyrtleLagerstroemia spp., hybrids & 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 JulyAloeAloe spp. & cvs.low 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 JulySagebrushArtemisia spp. (shrubby)low water, Central Valley1.07 gal/sq ft in JulyWild PrivetLigustrum vulgarelow water, Central Valley1.07 gal/sq ft in JulyCoralberrySymphoricarpos orbiculatus (SHADE)low water, Central Valley1.07 gal/sq ft in JulySydney Golden WattleAcacia longifolialow water, Central Valley1.07 gal/sq ft in JulyBlue Leaf WattleAcacia salignalow 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 forsythia, 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 forsythia in summer?

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

In July in the Central Valley, established forsythia needs about 1.1 gallons a day for a plant 4 feet across and about 4.3 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 forsythia change across California?

Yes. WUCOLS rates forsythia 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, not evaluated 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.

When should I prune forsythia?

Prune right after the spring flowers fade. Forsythia blooms on old wood, and cuts made after mid-July take off the buds for next spring. Remove some of the oldest stems and any dead wood each year to keep the shrub open.

Why is my forsythia not blooming?

Pruning after mid-July removes next spring's flower buds, so check when the shrub was last cut. Flowering is best in full sun, and a shaded plant blooms less. A long dry spell can also mean fewer flowers, so keep summer soakings deep.

Can I cut forsythia back hard?

Yes. An overgrown border forsythia can be cut almost to ground level to renew it. Do it right after flowering so the new stems have the whole season to grow. Keep up soil checks while they grow, so the regrowth does not stall in a dry spell.

Can forsythia grow in clay soil?

Yes. It tolerates poor and clay soils, but it does best where water drains away. In heavy clay, soak slowly and let the top few inches dry before watering again. Soil that stays saturated starves the roots of air and invites root rot.

Does forsythia lose its leaves in winter?

Yes, it is deciduous. Fall color is usually a plain yellow green, sometimes purplish, before the leaves drop. A bare shrub needs water only when winter rain fails and the soil is dry several inches down.

Can forsythia be used as a hedge?

Yes. Border forsythia works as an informal hedge or screen, and its arching stems also cover banks and slopes. Give a hedge its own drip line along both sides rather than relying on nearby lawn sprinklers.

More plant watering guides

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Sources