WateringTimesWatering plan, $19
Rhamnus alaternus, WUCOLS IV

How often to water Italian buckthorn in California

In July in the Central Valley, established Italian buckthorn in loam needs a deep watering about every 20 days: about 8.8 gallons each time for a plant 4 feet across, about 3.0 gallons a week. Italian buckthorn is a fast-growing, narrow evergreen shrub from the Mediterranean that reaches 12 to 15 feet tall and 6 to 8 feet wide. Dense, glossy dark green leaves make it a popular screen or clipped hedge in sun or shade. Small spring flowers give way to red berries that ripen dark purple, and birds carry the seed into wild areas.

ShrubRated for 4 of 6 zones

How often to water Italian buckthorn, 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 Italian buckthorn 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 a foot down beside a young hedge in its first summer means a slow, deep soak is due
  • Yellowing leaves and dieback in soil that stays soggy point to more water than this shrub needs
  • Seedlings coming up under trees and in nearby wild areas come from bird-spread berries, not from irrigation
  • Quick growth in its first years is normal for this shrub and not a sign of too much water

How to water it

  • Run drip lines along both sides of a new hedge so water reaches the whole root zone
  • Water deeply, about a foot down, then let the soil dry well before the next soak
  • Plant in sun or part shade in almost any soil, including spots that shift between sun and shade
  • Shear during the growing season to keep the hedge narrow and dense
  • Cut back irrigation once it is established, widening the watered strip only as the hedge fills out

Through the seasons

Water a new planting deeply through its first summer or two while roots spread. After that, winter rain and occasional summer soaks carry it along the coast and in the Central Valley. South Inland plants need a bit more. The shrub stays evergreen, flowers in spring and carries berries that turn from red to dark purple. WUCOLS rates Italian buckthorn low water on the north-central coast, in the Central Valley and on the south coast. In South Inland, it rates moderate water. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

A young Italian buckthorn can live in a large container as a narrow patio screen for a few years. Use a heavy pot with drainage holes and a well-drained mix. In summer heat, feel the mix 2 inches down every few days and water once it is dry there. Water until it drains, then empty the saucer. Shear to keep it in scale. In winter, water only when the mix has dried.

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
0.631.31.92.50.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.631.31.92.50.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Italian Buckthorn: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.78––
Feb0.210.260.320.87––
Mar0.350.430.461.3––
Apr0.470.610.561.61––
May0.580.830.641.95––
Jun0.640.990.692.29––
Jul0.641.070.792.51––
Aug0.60.950.742.33––
Sep0.50.720.61.86––
Oct0.350.470.461.33––
Nov0.190.220.330.9––
Dec0.120.140.260.68––
Year4.86.846.218.41––

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

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 Italian buckthorn, 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 Italian buckthorn in summer?

In July, established Italian buckthorn in loam needs a deep watering about every 20 days in the Central Valley, about every 27 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 Italian buckthorn need per day?

In July in the Central Valley, established Italian buckthorn needs about 0.4 gallons a day for a plant 4 feet across and about 1.7 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 Italian buckthorn change across California?

Yes. WUCOLS rates Italian buckthorn separately for each of the six California climate zones: low water in the North-Central Coastal zone, low water in the Central Valley zone, low water 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.

Is Italian buckthorn invasive in California?

It is on the watch list for invasive plants and has spread into scrub, chaparral and stream sides in the Bay Area and coast ranges. Birds, mammals and ants carry its seed, and it resprouts after cutting. Avoid planting it near wildlands, and never dump clippings with fruit.

How fast does Italian buckthorn grow?

It grows fast and makes a narrow screen within a few years, reaching 12 to 15 feet tall. It can also be trained as a small upright tree.

Can Italian buckthorn grow in shade?

Yes. It grows in sun or shade, which makes it useful for hedges that run from full sun into shade. Its narrow habit also suits paths and tight spaces.

What is variegated Italian buckthorn?

'Variegata' is a smaller form, 8 to 12 feet tall, with dark green leaves edged in creamy white. It brightens shady spots and needs the same watering as the species.

Can you overwater Italian buckthorn?

It tolerates regular water, but established plants need little in most of its rated zones. Soggy soil does not help it. Let the soil dry well between deep soakings.

More plant watering guides

Crape MyrtleWisteriaLantanaSalviaIrisesAloeSucculentsPomegranate Trees

Sources