Dendromecon harfordii, Island Bush Poppy
By Dan Songster, Golden West College Native Garden – 2010 October
Type: Evergreen Shrub
Light: Full sun to partial shade
Soil: Likes good draining soils but is adaptable
Water: Drought tolerant
There are two main varieties of our native Bush Poppy, the one from the mainland is Dendromecon rigida and its island cousin, the Island bush poppy, Dendromecon harfordii, is native to the Channel Islands off the coast of Southern California. The island bush poppy is considered more ornamental in most cases, easier for us to grow, and has a longer blooming season. It is this species we have in our native Garden here at GWC.
A dense evergreen shrub with a great combination of beautiful bluish-green leaves and bright buttery yellow flowers, it grows quickly to 5-8′ tall and 6-10′ wide. Its heaviest bloom period is in the spring-April through July. It’s not surprising that there are some flowers on it even now in the Garden since near the coast it can bloom almost year-round if pruned occasionally. Regarding pruning, I like tipping the plant back lightly but if it gets too big it can be treated more harshly taking half or more of the plant off around November or December. It re-sprouts generously and if those branches are immediately tipped back again it forms a more dense and floriferous plant the next year. If is an old, senescing plant then it is a risky move to prune it hard since it may not recover.
I have seen it planted as a loose formed espalier on an east wall and as a foundation plant hiding the side of a stairway near a back patio but normally this is used as a good sized but stunning background plant. In smaller gardens it can anchor the garden visually as its main focal point. It is large enough to compete with the lovely but aggressive Matilija Poppy, and you can imagine what it looks like with any of our native California Lilacs, (Ceanothus sp.) with their beautiful blue flowers!
A few words of caution. While it really does best in coarse, well drained soils, it can and does take clay but the life span is sometimes shorter, often only lasting 6 to 10 years. Also, while not as touchy as Flannelbush about summer water it does not like it and if repeatedly given water during hot summers it can fold in just a few years. Be careful when planting since just like many of the true Poppies it can be difficult to establish due to an especially brittle root system that will not accept careless handling. Don’t disturb the fragile root ball when planting it and don’t overwater and it should be fine. Like many of our natives, fall to mid winter is the best time of year to plant though with this plant we have been successful even with spring plantings.