This same species produces another variant that is, probably, my favorite euphorb of them all. E. amygdaloides purpurea (rubra) thrives in partial to fairly deep shade. It seeds around with abandon, which delights me, since it is rather short-lived. The foliage alone is striking enough to recommend it. Smoky purple to mahogany during the growing season, it turns nearly black during the cold days of winter. The flowers are a lovely contrast. The flower and foliage colors work so well together and compliment other plants so commendably, that I've been trying to use this color combination elsewhere in the garden, using other plants whose flowers or foliage repeat the scheme.
The plants stay between a foot and eighteen inches ((0.3 - 0.45 m) tall, but the flower stems can rise over two feet (0.6 m). They seldom stay erect, however, preferring to arch out from the weight of the flowerhead.
The bright chartreuse/yellow flowers start in early April for me and last until the end of May when they fade to a more subdued chartreuse (shown in the photo above) that remains nice right through June. Like many euphorbs, the flowering stems finally turn brown and die, needing to be cut back to the ground. In this photo, you can see the purple flower stems, still contrasting nicely with the bracts and developing seed pods. I simply adore this plant and have yet to find that it does not work well with anything it cares to put itself next to. Try it with the purple leafed Heucheras for a smashing combo.
Keep an eye out for the seedlings; they all have reddish stems and two long, oval, blue-green leaves.
I've moved adult plants growing in a foot or more of rotted woodchips without their getting upset, but it's better to relocate seedlings while they are still tiny if they put themselves where you don't want them. Good, well-draining soil will produce the best plants although they will grow in pure sand and gravel. Hardiness should be about the same as robbiae.
Also with purple foliage is Euphorbia dulcis 'Chameleon'. This is a fairly new acquisition of mine. I've only had it for a couple of years; this was it's first blooming season. The foliage starts out a deep, dusky purple, without the reddish tones of E. a. purpurea. Each leaf is highlighted by a lighter stripe. I haven't noticed "marbling" in the leaves that some catalog descriptions indicate. At the bottom of this photo, just above the plant tag, you can get a glimpse of the leaves - that lighter stripe shows where they are hiding in the shadows.
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