Washingtonia robusta

Washingtonia robusta

Washingtonia robusta or Mexican Fan Palm is, with its cousin Washingtonia filifera and Phoenix canariensis, this is the most widespread ornamental palm, from the tropics to temperate climates.

It’s easily mistaken for Washingtonia filifera. Growth is even faster but resistance to frost not as good as its name robusta would suggest.

The trunk is thinner, the corona of leaves less dense and it has more and harder spines along the petiole.

The leaves are fan shaped with less filaments than Washingtonia filifera.

The flowers grow in up to 4 m long stalks.

Usage:

Grown as a solitary, bordering avenues or as a skyline palm.

Leaves were used for weaving and construction of roofs.

Fruit are edible after boiling.

Common names:

Mexican Fan Palm, Mexican Washington Palm, Mexican Washingtonia, Thread Palm, Washington Fan Palm, Washingtonia

Synonyms:

Washingtonia sonorae, Washingtonia thurstoni, Washingtonia vuylstekeana

Origin:

Mexico (Baja California, Sonora)

Hardiness:

USDA Zone 8, -8 °C

Height:

22 m

Soil:

Any soil, well drained

Exposure:

Sun

Propagation:

Seed

Sowing instructions:

  • if the seeds are fresh, don’t bother soaking, if not, soak for 1 or 2 days in lukewarm water
  • sow in light soil
  • humidify
  • keep at 25-30°C
  • germination time: a couple of days if seeds are very fresh, 1 to 3 months otherwise
  • repot when the seedlings are big enough to handle, repot in individual pot

Care:

  • no particular care needed
  • drought resistant
  • feed during growing season

Remarks:

  • as with most palms, growth may be slow the first years but then accelerates
  • spines along the petiole are harder and more numerous than with Washingtonia filifera
  • both Washingtonia hybridize easily making it difficult to distinguish between them
  • Washingtonia are hermaphrodites, a single specimen can produce fruit and viable seed

In my garden:

These seedlings are 6 weeks old (after sowing!) and about 8 cm (3 inch) high. I told you their growth rate is very fast, didn’t I?
Washingtonia robusta seedlings

Before repotting:
Washingtonia robusta seedlings

The roots hit the bottom of the pot and started to grow horizontally and in circles. Palms usually need deep pots because they develop very long roots which go deep underground to look for water.
Washingtonia robusta seedling

The seedlings in bigger pots, actually they are soda bottles which I’ve cut in half. I put the upper half back on to form an individual and very cheap mini-greenhouse. This way, you don’t need to water very often. Checking once or twice a week is enough.
Washingtonia robusta seedlings

Careful: these babies can handle direct sunlight and high temperatures but for most plants you shouldn’t place such devices in direct sunlight as the temperature may get to warm and the plants literally boil. Also, there is a risk of sunburn when condensation water forms drops on the leaves which then act as a magnifying glass.

I didn’t have any problems with Washingtonia filifera and robusta: they are exposed to the south and withstood 30°C this spring and early summer and they grow rapidly, most of them forming their 3rd leaf. They are about 20 cm high now.

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