How often to water Canadian hemlock in California
In July on the north-central coast, established Canadian hemlock in loam needs a deep watering about every 13 days: about 55 gallons each time under a 10 foot canopy, about 29 gallons a week. Canadian hemlock, also called eastern hemlock, is a graceful conifer with drooping branch tips, flat sprays of short needles and tiny hanging cones. It comes from cool, moist forests in eastern North America. It does not tolerate drought and struggles in hot summers, so in California it belongs in cool, moist coastal gardens.
How often to water Canadian hemlock, month by month
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.
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 under the branches, and skip a watering after a good soaking rain.
How to tell it needs water
- Soil dry 4 inches down under the mulch at the edge of the branches signals that a hemlock needs a deep soak
- Needles browning at the branch tips after a hot, sunny spell can indicate scorch on top of dry soil
- A dull, dusty cast or fine speckling on the needles in dry heat warrants a look for mites, which thrive on stressed trees
- Yellowing needles over soil that stays soggy point to poor drainage, since hemlock needs moist but well-drained ground
- A thinning crown on a tree in afternoon sun suggests it needs more shade as well as steadier moisture
How to water it
- Water slowly under the outer half of the canopy with drip or a soaker hose, keeping the trunk dry
- Soak the soil 12 to 18 inches deep, then water again once the top few inches are dry
- Keep a few inches of shredded bark or pine needle mulch over the root zone to hold moisture and keep the roots cool
- Plant in part shade or a cool, sheltered spot in moist, slightly acidic soil that drains well
- Extend the watered ring outward each year as the branches spread
Through the seasons
A new Canadian hemlock needs deep soakings through its first two or three summers while roots spread into the surrounding soil. Established trees still need moisture through the dry season, because this conifer does not tolerate drought. As an evergreen, it keeps using some water through winter. Winter rain covers the cool months on the north-central coast, though a dry winter calls for a soil check. WUCOLS rates Canadian hemlock moderate water on the north-central coast. WUCOLS marks it as not suited to the Central Valley, the south coast, South Inland, the high desert and the low desert.
In pots
Dwarf, weeping and mounding forms of Canadian hemlock can grow for years in a large container. Check the mix 2 inches down every few days in summer, and more often in hot, dry wind. A potted hemlock dries fast, and drought browns its needles. Water until it runs from the drainage holes, then empty the saucer. Keep the pot in afternoon shade. Winter rain may keep it moist, but check the mix during dry spells.
- A year
- no figure
- Reference
- Sacramento climate table
- Counts
- Plant need, before sprinkler losses
WUCOLS lists Canadian Hemlock as not suited to this region for the Central Valley zone, so no monthly figure is computed here.
Monthly water need by climate zone
Canadian Hemlock: gallons per square foot per month, by WUCOLS climate zone
| Month | N. Coast | C. Valley | S. Coast | S. Inland | Hi Desert | Lo Desert |
|---|---|---|---|---|---|---|
| Jan | 0.37 | – | – | – | – | – |
| Feb | 0.53 | – | – | – | – | – |
| Mar | 0.87 | – | – | – | – | – |
| Apr | 1.18 | – | – | – | – | – |
| May | 1.46 | – | – | – | – | – |
| Jun | 1.61 | – | – | – | – | – |
| Jul | 1.61 | – | – | – | – | – |
| Aug | 1.49 | – | – | – | – | – |
| Sep | 1.24 | – | – | – | – | – |
| Oct | 0.87 | – | – | – | – | – |
| Nov | 0.47 | – | – | – | – | – |
| Dec | 0.31 | – | – | – | – | – |
| Year | 12 | – | – | – | – | – |
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 not suited to this region in the Central Valley, like Canadian hemlock. Plants that drink alike can share one valve and one schedule.
Sugar MapleAcer saccharumnot rated, Central Valleyno Central Valley rating
Queensland KauriAgathis robustanot rated, Central Valleyno Central Valley rating
CherimoyaAnnona cherimolanot rated, Central Valleyno Central Valley rating
Purple Orchid TreeBauhinia variegata (purpurea)not rated, Central Valleyno Central Valley rating
ToogBischofia javanicanot rated, Central Valleyno Central Valley rating
Clustered Fishtail PalmCaryota mitisnot rated, Central Valleyno Central Valley rating
White SapoteCasimiroa edulisnot rated, Central Valleyno Central Valley rating
FilbertCorylus maximanot rated, Central Valleyno Central Valley rating
Spotted GumCorymbia maculata (Eucalyptus maculata)not rated, Central Valleyno Central Valley rating
Dove TreeDavidia involucratanot rated, Central Valleyno Central Valley rating
Royal PoincianaDelonix regianot rated, Central Valleyno Central Valley rating
Triangle PalmDypsis decaryinot rated, Central Valleyno Central Valley rating
Mountain White GumEucalyptus dalrympleananot rated, Central Valleyno Central Valley rating
Rainbow EucalyptusEucalyptus degluptanot rated, Central Valleyno Central Valley rating
Roxburgh FigFicus auriculatanot rated, Central Valleyno Central Valley rating
Indian BanyanFicus benghalensisnot rated, Central Valleyno Central Valley ratingTurn this into minutes on your water days
Every city page has a calculator that takes Canadian hemlock, 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 much water does Canadian hemlock need per day?
In July on the north-central coast, established Canadian hemlock needs about 4.1 gallons a day under a 10 foot canopy and about 16 gallons a day under a 20 foot canopy. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.
Does watering for Canadian hemlock change across California?
Yes. WUCOLS rates Canadian hemlock separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, not suited to this region in the Central Valley zone, not suited to this region in the South Coastal zone, not suited to this region 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.
Can Canadian hemlock grow in full sun?
It handles sun only where summers stay cool and the soil stays moist. In hot weather, strong sun scorches the needles. In California, give it part shade or a cool coastal site.
Why are my hemlock needles turning brown?
Browning often follows dry soil or hot sun, two stresses this tree handles poorly. Check the soil 4 inches down first. Also look under the needles for mites or scale before adding more water.
How big does Canadian hemlock get?
The species can reach 40 to 70 feet tall and 25 to 35 feet wide, so it needs plenty of room. Dwarf and weeping forms stay far smaller and suit most home gardens.
Can I grow Canadian hemlock as a hedge?
Yes, it tolerates shearing as a hedge, though it looks best left unpruned. Run drip line along both sides of the row so every plant gets an even soak. Hedge plants compete for water, so check the soil between them.
Is Canadian hemlock poisonous like poison hemlock?
No. Poison hemlock is an unrelated weedy herb. This tree is a conifer and is considered nontoxic to cats, dogs and horses.
More plant watering guides
Sources
- WUCOLS IV plant water use classification for Tsuga canadensis, the University of California survey California agencies use for landscape plan reviewRead August 23, 2026 on wucols.ucdavis.edu
- Model Water Efficient Landscape Ordinance, adopted text and appendices, effective 2025-01-02 · monthly reference evapotranspiration per city, Appendix CRead August 23, 2026 on water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Water-Use-And-Efficiency/MWELO-Rulemaking/Final-MWELO-Text-and-Appendices_20250103.pdf
- UC Statewide IPM Program, irrigation scheduling using evapotranspirationRead September 30, 2026 on ipm.ucanr.edu/PMG/GARDEN/ENVIRON/evap.html
- Shaw and Pittenger, Landscape Irrigation System Evaluation and Management, UC Cooperative Extension, 2009Read September 30, 2026 on ucanr.edu/sites/default/files/2013-02/160836.pdf
- Pittenger, Water Management in Gardens and Landscapes, UC Riverside, 2017Read September 30, 2026 on ucanr.edu/sites/default/files/2017-03/258022.pdf