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I've got five large clumps of these plants on the south side of my Michigan home and each year they grow like crazy until mid-to-late July and then they start to die from the bottom up (yellowing and browning very quickly), until only a small little canopy of green is left. I have tried to increase their watering with no luck, so I'm starting to suspect they are just getting too much sunlight.

Does anyone know what these are?

They develop purple flowers mid-summer, each atop a single, almost woody stalk, and each stalk has their own tiny root system.

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  • I don;t suppose you have any images of the flowers do you? If so, it would be useful to see them, especially since you describe them as having little roots... Otherwise, what do the flowers looks like (daisy like or not, size, shape, how many petals, double, single, triple, stamens and so on) Are they herbaceous perennials (meaning they disappear completely in winter) – Bamboo Jul 9 '18 at 22:15
  • @Bamboo Unfortunately, I do not. I found a blurry pic from when I first bought my house where you can just make out the purple, but you can't see any detail. At the very least, I know that the previous owners were able to get them to survive the summer so I must be doing something wrong! I can tell you that they do die all the way down to the ground in winter. – Ryan Jul 10 '18 at 14:42
  • Do you know if the flowers were purple daisies with yellow-gold centers? – Jurp Jul 12 '18 at 0:34
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Sure looks like a New England Aster - especially the Purple Dome cultivar. We would know for sure if we had pictures of the flowers. I've seen the die-back you describe on my own Purple Domes and assumed it was a drainage issue due to my having planted them in heavy clay.

  • There is quite a bit of clay here that has caused problems before. I've reduced my watering schedule a bit to hopefully give it a bit more time to drain. We'll see if that has any effect. – Ryan Jul 10 '18 at 14:46
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My first impression is Euphorbia. Purple flowers is a stumper. This Euphorbia has red brown flowers and although the form and leaf arrangement is correct...the leaves look too herbaceous to be this plant.

When you break the stem is there a definitive milky sap? Do not get it on your hands or skin. Have you noticed this? Could you go break a chunk off using gloves? Euphorbia mellifera

How about Euphorbia austriaca? Euphorbia austriaca

Have you ever fertilized your landscape plants? The thing I just found is that Euphorbia shouldn't be fertilized UNTIL you see the yellowing bottom leaves. I am not so sure I like telling people how to recognize fertilizer deficiency before fertilizing. Sort of an advanced skill.

Nitrogen is a 'mobile chemical' (erroneously called nutrients). That means when the plant is finding no more Nitrogen in the soil it 'transfers' the nitrogen in the older leaves to the new leaves where that nitrogen is best used. The best leaves of the plant are then able to make food for the plant, they get the chemistry and water. The older leaves are abscised from the plant (yellowing first) and dumped so they don't take up carbohydrates and water needed by the best producers of food, the top leaves. This way the plant survives.

Have you used any fertilizer? Good old Osmocote 14-14-14 once a year would stop these beautiful plants yellowing at the bottom. Wear gloves when handling. Teach kids to never mess with plants until they are able to recite the scientific name!

The genus Euphorbia amazes me every time I get to look at the myriad forms! Cactus to shrubs to perennials to trees! The one thing that ties all those species together is Architectural. Like a robot plant. If your plant exudes a milky sap you have Euphorbia. The species is another matter. Purple flowers is another matter...

  • They're not Euphorbia... I don't know what they are, but I know what they are not! Intriguing though.... – Bamboo Jul 9 '18 at 22:16
  • Why do you think not Euphorbia, Bamboo? – stormy Jul 9 '18 at 22:17
  • Purple flowers? In the middle of summer? Plus the foliage arrangement and general appearance... – Bamboo Jul 9 '18 at 22:19

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