WateringTimesWatering plan, $19
Yucca filamentosa ssp. & cvs., WUCOLS IV

How often to water Adam's needle in California

In July in the Central Valley, established Adam's needle 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. Adam's needle is a yucca that forms a rosette of stiff, sword-shaped leaves edged with curly white threads. In late spring or summer it sends up a tall stalk of creamy white, bell-shaped flowers, and offsets slowly build a small colony. It tolerates drought, heat, salt spray and poor soil, but it needs good drainage.

ShrubSucculentRated for 6 of 6 zones

How often to water Adam's needle, 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 Adam's needle 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 6 inches down beside the rosette in summer heat means Adam's needle is ready for a deep soak
  • Leaf tips drying back during a long, hot summer can show the roots have gone too dry
  • Spotted or blighted leaves on plants in poorly drained ground point to excess moisture
  • A soft, rotting base or a rosette that pulls loose points to rot from wet soil
  • A flower stalk that browns after bloom has simply finished and can be cut off

How to water it

  • Water Adam's needle at the soil around the rosette, never into the leaf crown
  • Wet the soil to about a foot, then wait until it has dried well down before watering again
  • Plant in full sun or part shade in sandy or rocky soil with sharp drainage
  • Use gravel or bare soil around the base instead of a thick organic mulch
  • Water a little wider as offsets fill in around the parent rosette

Through the seasons

Water a new Adam's needle through its first summer whenever the soil dries, so roots spread beyond the planting hole. Established rosettes tolerate drought and need little water in most of California, though the high desert calls for more. The leaves are evergreen, and the flower stalk rises in late spring or summer. Irrigation matters most during long hot spells. On the south coast WUCOLS rates Adam's needle very low water. Low water is the rating for the north-central coast, the Central Valley, South Inland and the low desert. The high desert rating is moderate water.

In pots

Adam's needle grows well in a heavy pot of gritty, fast-draining mix. In summer heat, probe the mix every few days, and water only after the top 2 to 3 inches have dried. Let water run freely out of the holes and leave none standing in the saucer. Keep the pot where its sharp leaf tips will not catch passersby. In winter, water sparingly, since cool, wet mix can rot the roots.

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
0.761.52.33.00.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.761.52.33.00.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Adam's Needle: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.080.310.740.31
Feb0.210.260.080.350.930.37
Mar0.350.430.110.521.460.61
Apr0.470.610.140.641.890.78
May0.580.830.160.782.390.98
Jun0.640.990.170.922.851.12
Jul0.641.070.213.041.14
Aug0.60.950.190.932.791.04
Sep0.50.720.150.742.140.83
Oct0.350.470.110.531.460.6
Nov0.190.220.080.360.930.38
Dec0.120.140.070.270.650.27
Year4.86.841.557.3721.278.43

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 Adam's needle. 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 Adam's needle, 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 Adam's needle in summer?

In July, established Adam's needle in loam needs a deep watering about every 20 days in the Central Valley, about once a month or less on the south coast and about every 22 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 Adam's needle need per day?

In July in the Central Valley, established Adam's needle 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 Adam's needle change across California?

Yes. WUCOLS rates Adam's needle separately for each of the six California climate zones: low water in the North-Central Coastal zone, low water in the Central Valley zone, very low water in the South Coastal zone, low water in the South Inland zone, moderate water in the High and Intermediate Desert zone, low water in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

What are the threads on Adam's needle leaves?

They are curly, threadlike fibers that peel from the leaf edges. The leaves have some of the strongest fibers of any North American native plant. The threads are normal and not a sign of stress.

Should I cut off the flower stalk on Adam's needle?

Yes, cut the stalk at the base once the flowers fade. It keeps the plant tidy and has no effect on watering.

Is Adam's needle deer resistant?

Yes. It resists deer and rabbits as well as salt spray, drought and heat. That toughness still depends on soil that drains well.

How do I propagate Adam's needle?

Divide offsets from the parent, take root cuttings or sow seed. Water new divisions lightly until they root, then let the soil dry between drinks.

Can you overwater Adam's needle?

Yes. In poorly drained ground its leaves can develop leaf spots or blight, and the roots can rot. Allow a good dry spell in the soil between drinks.

More plant watering guides

Evergreen EuonymusCrown of ThornsCreeping SpurgeRigid SpurgeFleeceflowerCarolina JessamineYellow Horned PoppyHoney Locust

Sources