Plant of the Month (November) : Ashy-leaf Buckwheat - Eriogonum cinereum

It’s strange to have buckwheats blooming this time of year.  But the garden is young (got a little extra water this summer), the weather’s been capricious and our Ashy-leaf Buckwheat is blooming like crazy.  This IS a later blooming species (summer-fall), so we shouldn’t be too surprised.  But November is ‘late-normal’  even for this species.

Ashy-leaf Buckwheat is a coastal native.  It grows wild on dunes and coastal bluffs from Santa Barbara County to Los Angeles County.  Its local range stretches inland for several miles on the Palos Verdes Peninsula, but in general it’s a plant of low-elevation (< 500 ft) coastal areas.  While Mother Nature’s Backyard is not coastal (about seven miles from the coast) - and our soil is loam (not sand) -  we decided to try this local favorite.   So far, so good!

Ashy-leaf Buckwheat shares many characteristics with other native buckwheats (see Plant of the Month - July, 2012 for more on this interesting genus).   It’s a half-woody sub-shrub with many slender branches.  The overall shape is mounded to sprawling depending on light, soil type and other conditions.    On coastal dunes and bluffs it sprawls close to the ground, pruned by the harsh winds and blowing sand and salt.  Further inland – and in our garden – it forms a mound two to three feet high and as much as 5 feet across.   Like many local sub-shrubs, this species grows to full size in 1-2 years – relatively quickly for a California native shrub.

As suggested by its common name, the Ashy-leaf Buckwheat has light colored leaves compared to other local buckwheats.  It is grown for both its attractive foliage and its flowers.    Early in the season, the leaves are a lovely pastel green that contrasts beautifully with the flowers.  As the plant dehydrates during the dry season, the leaves become curled and ashy-looking.  The light color of the leaves is due to long trichomes (plant hairs) that cover the leaves and stems (see picture below). 

While most native buckwheats have hairs on young leaves, this species retains them longer than most.   The leaves of Ashy-leaf Buckwheat are also slightly larger (at least 1 inch long) than two other local shrubby buckwheats (Eriogonum fasciculatum and Eriogonum parvifolium) – though not as large as those of the Giant Buckwheat/St. Catherine’s Lace (Eriogonum giganteum). 

 

 

The flowers are another attractive feature of the Ashy-leaf Buckwheat.  The tiny flowers are packed into dense, ball-like clusters at the ends of flowering stalks.  The perianth (non-sexual part of the flower) is white to pale pink (more usual).  In buckwheats, the perianth is composed of leaf-like bracts, rather than petals in the strictest sense.  The sexual parts of the flower extend beyond the perianth to promote pollination (see photo below).  The flower color is among the prettiest we know for a pink-purple themed garden.

 

Like all native buckwheats, Ashy-leaf Buckwheat is an important habitat plant, particularly for insects.   The flowers attract an array of insect visitors including bees, butterflies, pollinator flies, wasps and butterflies (particularly the smaller butterflies like Skippers, Blues and Hairstreaks).  Planting buckwheats for pollinators and butterflies makes sense; but who would want to attract more wasps to their garden?     Perhaps you, if you want their help in controlling aphids, mealy bugs, scale insects and other common garden pests.  

Birds and other small creatures eat the seeds in late summer and fall.  This is a good reason to resist the urge to prune off the dead flowers too soon.  If you wait until later – or just let nature take its course – you can also enjoy the red-brown color of the mature bracts and seeds.   Their color and shape add welcome variety to the autumn garden.

Buckwheats like sun near the coast and a little afternoon shade in hotter inland gardens.   We’ve planted several plants in different areas of the garden – some with more shade than others.  This is often a good strategy if you’re not sure how well a plant will do under different light/temperature conditions.  

Ashy-leaf Buckwheat likes a well-drained soil.  While native to sandy soils, it can succeed in local clays and loams as long as it is not over-watered (see this month’s post on Soil Testing (October, 2012) to learn more about your garden’s soil).  Don’t worry if your soil pH is on the high end.  This species can take soils that are even a bit above 8.0   

Newly planted Ashy-leaf Buckwheats need moist soil while getting established (the first 3-4 months).  That’s one reason why late fall/early winter is the best time to plant them.  Once established, they need only occasional summer water – none on the immediate coast.   In most gardens,  watering several times during the dry season is adequate.  Plants look best – and are healthiest - when treated as Water Zone 1-2 (clay/loam soils) or 2 (sandy soils).  See our April 2012 post for more on Water Zone Gardening.    

Like many local native plants, Ashy-leaf Buckwheat doesn’t need fertilizer.   It also doesn’t like much organic mulch once it gets established (see our July 2012 post on Mulches).   If you want to use a mulch, we suggest an inorganic one or a thin (1-2 inch layer) of organic mulch just to get the plant started.    As the  mulch breaks down, the plant itself will supply sufficient mulch for its needs.

In general, native buckwheats don’t need much pruning.  Trim off the dead seed heads once the birds have picked them clean in late fall.  Remove dead branches when you notice them during the growing season.  Other than that, the plant has a nice natural shape that requires little assistance.  If you want a bushier plant, cut back the branch tips by several inches the first fall.  If your plant becomes raggedy-looking after 3-5 years, you can prune it down to about 8 inches in late fall. 

For our 1-page gardening sheet on this plant see: http://www.nbs.csudh.edu/biology/projectsound/native_plants/pdf/Eriogonum_cinereum.pdf

 

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We encourage you to share your experiences with Ashy-leaf Buckwheat in the Comments box below.  And as always, we welcome your comments and questions at: mothernaturesbackyard10@gmail.com