WateringTimesWatering plan, $19
Pelargonium sidoides, WUCOLS IV

How often to water South African geranium in California

In July in the Central Valley, established South African geranium in loam needs a deep watering about every 20 days: about 2.2 gallons each time for a plant 2 feet across, about 0.8 gallons a week. South African geranium is a small evergreen perennial from rocky, summer-rainfall grasslands of the Eastern Cape. It forms a compact rosette of soft, gray-green, heart-shaped leaves that are curiously scented. Dainty, nearly black burgundy flowers float above on long, wiry stems in spring and summer. It needs good drainage and mild winters.

Ground coverPerennialRated for 4 of 6 zones

How often to water South African geranium, month by month

Your city
Plant width
2 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 South African geranium 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

  • Gray leaves of South African geranium going limp while the soil is dry an inch or two down mean it needs water
  • Older leaves yellowing now and then are normal and can be pulled
  • Stems rotting at the crown in wet soil point to poor drainage
  • Orange-brown spots under the leaves point to pelargonium rust, not thirst

How to water it

  • Water at the base of the rosette, keeping the leaves dry
  • Plant in cool sun to part shade, with afternoon shade in hot areas
  • Use well-drained soil, raised if your ground is heavy
  • Deadhead spent flower stems and pull yellowing leaves
  • Let the top inch or two of soil dry before the next drink

Through the seasons

Water new plants regularly until they root in. Established plants like the soil to dry an inch or two between drinks. It stays evergreen in mild winters and blooms from spring into summer, and winter rain covers the cool months on the coast. Afternoon shade helps in hot inland summers. WUCOLS rates South African geranium moderate water on the north-central coast. The Central Valley, the south coast and South Inland carry the same low water rating. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

South African geranium suits a pot or window box, where its dark flowers can be seen up close. Use a well-drained, loam-based mix. Water when the top inch dries, until water runs out the base. In summer heat, check every couple of days and give afternoon shade. Keep the saucer empty. Deadhead often. In winter, water sparingly and move it under cover if frost threatens.

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
0.400.811.21.60.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.400.811.21.60.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

South African Geranium: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.160.310.31––
Feb0.530.260.320.35––
Mar0.870.430.460.52––
Apr1.180.610.560.64––
May1.460.830.640.78––
Jun1.610.990.690.92––
Jul1.611.070.791––
Aug1.490.950.740.93––
Sep1.240.720.60.74––
Oct0.870.470.460.53––
Nov0.470.220.330.36––
Dec0.310.140.260.27––
Year126.846.27.37––

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 South African geranium. Plants that drink alike can share one valve and one schedule.

BougainvilleaBougainvillea & spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyAgapanthusAgapanthus orientalislow water, Central Valley1.07 gal/sq ft in JulyGeraniumsPelargonium x hortorum and 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 JulyIrisesIris germanicalow 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 JulyYarrowAchillea millefolium (non-native hybrids)low water, Central Valley1.07 gal/sq ft in JulyMountain AlyssumAlyssum montanumlow water, Central Valley1.07 gal/sq ft in JulySagebrushArtemisia spp. (shrubby)low water, Central Valley1.07 gal/sq ft in JulySilver SageSalvia argentealow water, Central Valley1.07 gal/sq ft in JulyPurple MulleinVerbascum phoeniceumlow water, Central Valley1.07 gal/sq ft in JulySilvery YarrowAchillea clavennaelow water, Central Valley1.07 gal/sq ft in JulyFern Leaf YarrowAchillea filipendulinalow 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 South African geranium, 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 South African geranium in summer?

In July, established South African geranium 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 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 South African geranium need per day?

In July in the Central Valley, established South African geranium needs about 0.1 gallons a day for a plant 2 feet across and about 0.4 gallons a day for a plant 4 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 South African geranium change across California?

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

Are the flowers really black?

They are a very dark burgundy that looks almost black. They are small and held on long, wiry stems. Bloom runs through spring and summer.

Is the plant sold under this name the true species?

Many plants sold as South African geranium are hybrids with Pelargonium reniforme, according to a noted breeder. The true species has smaller, fragrant flowers and no stems. Hybrids form small mounds instead.

Is South African geranium frost hardy?

It needs mild, mostly frost-free winters. Bring pots under cover on frosty nights. Gardens with hard freezes are a poor fit.

What pests bother South African geranium?

Aphids can appear in spring. Pelargonium rust and viruses also affect it. Remove spotted leaves and keep foliage dry.

How big does South African geranium get?

It stays small, about 12 to 18 inches tall and wide. The flower stems rise above the leaves. Use it at the front of a bed or in a pot.

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Sources