The west’s best blues
This genus of shrubs is native primarily to the west coast with the majority of species in California and then Oregon. We love ‘Wild Lilacs’ as they are sometimes called for several important reasons.
They represent excellent climate adaptation. Almost all are native to winter wet/summer dry conditions. They thrive in our climate with little intervention from the gardener. Flowers: blue- no other shrub comes close to the display of blue flowers housed in this genus. The most blue cultivars and species hail from central and northern California and have been grown in our region for eons. Fast growing and extraordinarily drought tolerant they cruise through our dry summers with no visible signs of stress. In fact they loathe the combination of wet/warm soils. So no summer water is advised.
They range from large shrubs to ground covers and are useful in a host of situations. Full sun and average well drained soil including clay soils on slopes. They even fix nitrogen with their roots which means they earn their own lunch. Lifespan: typically they live on average 10 years but for the ground cover types which persist quite a bit longer. They make ideal plants for new gardens as they grow rapidly and even years after their demise the soil beneath them remains enriched, loose and friable. A great place to grow tomatoes.
Ceanothus are Oregon’s largest genus of native shrubs. A total 13 species populate the state from the coast to the high Cascades. In Southwestern Oregon a conglomeration of species even results in hybrids. It should be said that there are several species of native Oregon Ceanothus that are spectacular in the wild but resist garden culture with a vengeance. Ceanothus pumila Siskiyou Mat and Ceanothus prostratus Squaw mat (sic) are amazing when seen in bloom in the spring. Its tempting to fall in love with the idea of replicating garlands of blue as you see Ceanothus prostratus on the rim of Crater Lake. Or to drape a patch of Siskiyou mat over a boulder. There must be a secret to their cultivation. As of yet we have not found it. Other native Ceanothus species make exemplary garden plants. Both Ceanothus thyrsiflorus and its cultivars and Ceanothus cuneatus are incredibly successful garden plants.
We have introduced several varieties of Ceanothus thyrsiflorus native from Lane county Oregon to Santa Barbara County California and we’re always on the search for more Oregon cultivars. Water them until you see them start growing in earnest and then taper off. And then only the water that falls from the sky. To prune, tip prune after blooming to resize, encourage density. Usually it is not necessary. The size of Ceanothus is completely dependent on the fertility of the soil. Rich soil HUGE, poor soil restrained. They make wonderful urban shrubs- tolerant of extreme reflected heat as well as hot dry places.
Ceanothus are very important for spring pollinators. A shrub in full bloom is a fascinating mass of bees, hover flies and many more pollinators. Some of our earliest butterflies to emerge also feast on Ceanothus. There is a place and a use in every garden for this fascinating group of west coast natives.
Climate Adapted Plants for Gardeners in the PNW