WateringTimesWatering plan, $19
Forsythia X intermedia, WUCOLS IV

How often to water border forsythia in California

In July in the Central Valley, established border 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. Border forsythia is a fast-growing deciduous shrub whose long arching stems fill with yellow bell flowers in early spring, before the leaves open. Left unpruned it reaches 8 to 10 feet tall and spreads even wider. A young plant needs regular deep soaks for its first few years. Once rooted it rides out dry spells fairly well, and waterlogged ground troubles it more than thirst.

ShrubRated for 3 of 6 zones

How often to water border 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 border 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 under the outer stems of a young forsythia means it is time for a deep soak
  • Shriveled leaves in a long hot spell, with dry soil below, can show the shrub has run short of water
  • Fine pale stippling or a bronze cast on the leaves in hot, dusty weather can be spider mites, which hit water-stressed shrubs hardest
  • Soil still soggy days after a soak means the site drains too poorly for forsythia, so hold off on water
  • Scattered dead stems on a plant with moist soil can come from dieback disease, which extra water will not fix

How to water it

  • Water a young forsythia over its root ball and a little beyond it, then widen that circle as the arching stems spread
  • Soak slowly until water reaches 12 to 18 inches down, then let the top few inches dry before the next soak
  • Run drip emitters or a soaker hose under the stems instead of spraying the whole shrub
  • Spread a few inches of compost or wood chip mulch over the root zone, leaving a bare circle around the base of the stems
  • Plant in any soil that drains freely, and avoid low spots where winter rain stands

Through the seasons

Water a new forsythia regularly through its first few summers, until its roots reach well past the planting hole. After that it needs deep, spaced soaks only in dry spells. Flowers open on bare stems in early spring, then leaves follow and hang on late into fall before they drop. The leafless shrub rests through winter. Winter rain covers the cool months on the north-central coast and in the Central Valley. WUCOLS rates border forsythia low water on the north-central coast. It rates moderate water in the Central Valley and in South Inland, where summer soil checks matter most. WUCOLS marks it as not suited to the south coast, the high desert or the low desert.

In pots

A full-size forsythia soon outgrows any pot, but dwarf cultivars that stay about 2 to 4 feet tall can live in a container. Choose a large pot with open drainage holes. Check the mix 2 inches down every few days in summer, and daily during Central Valley or South Inland heat waves. Water until it runs from the holes, then empty the saucer. The bare shrub uses little water in winter, so let the mix dry a little between soakings and check it after rain.

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

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.4–0.78––
Feb0.210.65–0.87––
Mar0.351.09–1.3––
Apr0.471.52–1.61––
May0.582.08–1.95––
Jun0.642.48–2.29––
Jul0.642.67–2.51––
Aug0.62.39–2.33––
Sep0.51.8–1.86––
Oct0.351.18–1.33––
Nov0.190.56–0.9––
Dec0.120.34–0.68––
Year4.817.11–18.41––

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 border 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 border 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 border 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 border forsythia in summer?

In July, established border forsythia in loam needs a deep watering about every 8 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 border forsythia need per day?

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

Yes. WUCOLS rates border forsythia separately for each of the six California climate zones: low water in the North-Central Coastal zone, moderate water in the Central Valley zone, not suited to this region in the South Coastal zone, moderate water 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. Flowers form on the previous year's stems, so cuts made after midsummer remove next spring's buds. Each year, take out some of the oldest stems at the base to keep new flowering shoots coming.

Why is my forsythia not blooming?

Late pruning is one cause, since it cuts off the flower buds. Shade is another, because forsythia flowers more heavily in full sun. After a hard renovation cut, expect no flowers the following spring.

Is forsythia toxic to dogs and cats?

Forsythia is listed as non-toxic for dogs, cats and horses. That makes it a reasonable shrub for a yard where pets roam.

Can forsythia be grown as a hedge?

Yes, it makes an informal flowering hedge or mass planting. Space plants 18 inches to 2 feet apart for a dense hedge, or up to 3 feet apart for a looser look. Trim right after flowering and remove a few old stems so fresh shoots rise from the base.

Does forsythia grow in poor or salty soil?

Yes. It tolerates poor garden soil, urban conditions and salt. Waterlogged ground is what it handles badly, so drainage matters more than richness.

Why does my forsythia have flat, fused-looking stems?

Flattened shoots that look like several stems pressed together are fasciation. It looks odd but does not affect the health of the shrub. Prune the stem out if you dislike the look.

More plant watering guides

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Sources