WateringTimesWatering plan, $19
Magnolia stellata, WUCOLS IV

How often to water star magnolia in California

In July in the Central Valley, established star magnolia 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. Star magnolia is a slow-growing deciduous shrub or small tree, often multi-stemmed, with fragrant white flowers shaped like stars. Blooms open in late winter to early spring, before the leaves, so late frost can brown them. It needs consistent, even moisture in summer and dislikes soil that is either very dry or soggy.

ShrubRated for 3 of 6 zones

How often to water star magnolia, 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 star magnolia 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

  • Dry soil 2 to 3 inches below the mulch in summer means star magnolia is due for water
  • Leaves browning at the edges in summer heat can follow a dry root zone, since it needs even moisture
  • Browned petals after a cold night are frost damage on the early flowers, not a watering problem
  • Yellow leaves with green veins in alkaline soil point to chlorosis rather than thirst
  • Leaves yellowing and dropping in soggy ground show the roots are too wet

How to water it

  • Run drip or a soaker beneath star magnolia's branches so the soil there is moistened evenly
  • Soak about a foot deep, then water again when the top couple of inches dry
  • Plant in moist, rich, well-drained loam that is acidic to neutral, in full sun for the best bloom
  • Keep a layer of organic mulch over the roots to hold moisture even through summer
  • Spread the watered area outward as the shrub widens toward 10 to 15 feet

Through the seasons

Keep a new star magnolia evenly moist through its first summers while roots spread. Established plants still need consistent moisture in summer, since they tolerate neither dry nor waterlogged soil. Flowers open in late winter or early spring before the leaves, which emerge bronze, turn dark green and color yellow in fall. Seed pods split in late summer to show bright orange seeds. WUCOLS rates star magnolia moderate water on the north-central coast, in the Central Valley and in South Inland. It is marked not suited to the high desert, the low desert and the south coast.

In pots

Star magnolia grows slowly, so a young plant can live in a large container for several years. Fill a draining pot with rich, slightly acidic mix. During summer heat, test the top 2 inches every few days, and water before the whole root ball dries. Tip out the saucer once the excess has drained so roots never sit wet. In winter, move the pot out of a sunny, south-facing spot so warmth does not push buds open ahead of a frost.

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

Star Magnolia: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.4–0.78––
Feb0.530.65–0.87––
Mar0.871.09–1.3––
Apr1.181.52–1.61––
May1.462.08–1.95––
Jun1.612.48–2.29––
Jul1.612.67–2.51––
Aug1.492.39–2.33––
Sep1.241.8–1.86––
Oct0.871.18–1.33––
Nov0.470.56–0.9––
Dec0.310.34–0.68––
Year1217.11–18.41––

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 star magnolia. 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 star magnolia 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 star magnolia, 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 star magnolia in summer?

In July, established star magnolia 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 star magnolia need per day?

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

Yes. WUCOLS rates star magnolia separately for each of the six California climate zones: moderate 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.

Why did my star magnolia flowers turn brown?

The flowers open early and are easily damaged by frost. A planting spot away from southern exposure delays bloom and reduces the risk. Browned flowers are not a sign of thirst.

Why are my star magnolia leaves yellow?

In alkaline soil it often becomes chlorotic, with yellow leaves and green veins. Soggy soil can also yellow leaves. Check drainage and soil pH before adding water.

Does star magnolia need full sun?

It tolerates partial shade but flowers best in full sun. Full sun dries the soil faster, so keep mulch in place and check moisture through summer.

How big does star magnolia get?

It grows slowly to about 15 to 20 feet tall and 10 to 15 feet wide, often with several stems. Plan the watered area for that spread.

Can you overwater star magnolia?

Yes. It needs even moisture but is intolerant of wet soil. Let the surface dry slightly between soakings and avoid low spots where water stands.

More plant watering guides

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Sources