How often to water Double Knock Out rose in California
In July in the Central Valley, established Double Knock Out rose 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. Double Knock Out is a compact shrub rose about 3 to 4 feet tall and wide, with double cherry-red flowers. It blooms in spring and repeats heavily until frost, and its petals fade to pale pink before falling. Like the rest of its group, it was bred for a long bloom season and strong resistance to black spot, and it blooms reasonably well even in partial shade.
How often to water Double Knock Out rose, 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 the plant covers, and skip a watering after a good soaking rain.
How to tell it needs water
- Soil dry 3 inches down under the shrub in summer means Double Knock Out rose can take a deep drink
- Rebloom slowing in midsummer heat can follow dry soil
- Leaves drooping in late afternoon can indicate thirst
- Yellow leaves over standing water or soggy soil point to poor drainage
How to water it
- Water deeply at the base during dry spells to keep flowers coming
- Let the upper few inches dry between waterings
- Plant in full sun to part shade in neutral to acidic, loamy, well-drained soil
- Mulch the roots to hold moisture and even out soil temperature
- Prune lightly in late winter to manage size
Through the seasons
Water a new rose regularly through its first summer. Established plants need deep watering during dry periods to keep a continual supply of flowers, with mulch to hold moisture. It is semi-deciduous and flowers from spring until frost, with petals fading to pale pink and then tan before they drop. In the Central Valley, WUCOLS rates Double Knock Out rose low water. WUCOLS has not evaluated it for the north-central coast, the south coast, South Inland, the high desert or the low desert.
In pots
Double Knock Out rose does well in a large pot on a sunny patio, where it blooms for months. Use a loamy, well-drained mix. Water when the top couple of inches are dry, until water drains out. In summer heat, check every day or two. Do not leave the pot in a saucer of water. Remove spent blooms to encourage quicker rebloom. In winter, water only when the mix dries.
- A year
- 6.84 gal per sq ft
- Reference
- Sacramento climate table
- Counts
- Plant need, before sprinkler losses
Monthly water need by climate zone
Double Knock Out Rose: gallons per square foot per month, by WUCOLS climate zone
| Month | N. Coast | C. Valley | S. Coast | S. Inland | Hi Desert | Lo Desert |
|---|---|---|---|---|---|---|
| Jan | – | 0.16 | – | – | – | – |
| Feb | – | 0.26 | – | – | – | – |
| Mar | – | 0.43 | – | – | – | – |
| Apr | – | 0.61 | – | – | – | – |
| May | – | 0.83 | – | – | – | – |
| Jun | – | 0.99 | – | – | – | – |
| Jul | – | 1.07 | – | – | – | – |
| Aug | – | 0.95 | – | – | – | – |
| Sep | – | 0.72 | – | – | – | – |
| Oct | – | 0.47 | – | – | – | – |
| Nov | – | 0.22 | – | – | – | – |
| Dec | – | 0.14 | – | – | – | – |
| Year | – | 6.84 | – | – | – | – |
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 Double Knock Out rose. Plants that drink alike can share one valve and one schedule.
LavenderLavandula spp. & cvs.low water, Central Valley1.07 gal/sq ft in July
RosemaryRosmarinus officinalislow water, Central Valley1.07 gal/sq ft in July
BougainvilleaBougainvillea & spp. & cvs.low water, Central Valley1.07 gal/sq ft in July
Olive TreesOlea europaea ssp. & cvs.low water, Central Valley1.07 gal/sq ft in July
Crape MyrtleLagerstroemia spp., hybrids & cvs.low water, Central Valley1.07 gal/sq ft in July
LantanaLantana camara ssp. & cvs.low water, Central Valley1.07 gal/sq ft in July
SalviaSalvia greggii ssp., cvs. & hybridslow water, Central Valley1.07 gal/sq ft in July
AloeAloe spp. & cvs.low water, Central Valley1.07 gal/sq ft in July
SucculentsEcheveria spp. & cvs.low water, Central Valley1.07 gal/sq ft in July
JunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in July
Russian SagePerovskia spp. & cvs.low water, Central Valley1.07 gal/sq ft in July
SagebrushArtemisia spp. (shrubby)low water, Central Valley1.07 gal/sq ft in July
Wild PrivetLigustrum vulgarelow water, Central Valley1.07 gal/sq ft in July
CoralberrySymphoricarpos orbiculatus (SHADE)low water, Central Valley1.07 gal/sq ft in July
Sydney Golden WattleAcacia longifolialow water, Central Valley1.07 gal/sq ft in July
Blue Leaf WattleAcacia salignalow water, Central Valley1.07 gal/sq ft in JulyTurn this into minutes on your water days
Every city page has a calculator that takes Double Knock Out rose, 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 Double Knock Out rose need per day?
In July in the Central Valley, established Double Knock Out rose 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 Double Knock Out rose change across California?
Yes. WUCOLS rates Double Knock Out rose separately for each of the six California climate zones: not evaluated in the North-Central Coastal zone, low water in the Central Valley zone, not evaluated in the South Coastal zone, not evaluated in the South Inland zone, not evaluated in the High and Intermediate Desert zone, not evaluated in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.
Do I need to deadhead Double Knock Out rose?
No, but removing spent blooms helps it rebloom sooner. Petals fade and drop on their own. Water steadily for more flowers.
Does Double Knock Out rose get black spot?
It was bred to be particularly resistant to black spot. Water at the base to keep leaves dry. Good air flow helps too.
How much pruning does Double Knock Out rose need?
It needs less pruning than most roses. Prune lightly in late winter to control size. Remove dead canes any time.
Can Double Knock Out rose grow in part shade?
It is one of the few roses that blooms reasonably well in partial shade. Full sun gives the most flowers. Shade slows drying.
Do deer eat Double Knock Out roses?
Roses can be damaged by deer and rabbits. Protect young plants if they visit. Fencing helps.
More plant watering guides
Sources
- WUCOLS IV plant water use classification for Rosa 'Radtko', 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