Answer: Lambs ear is known to resent summer heat and humidity and often browns out much as you described, as will the other two plants you mentioned. Silver Mound artemesia is particularly susceptible to this. Another common cause for this browning is a heavy poorly drained soil as all three of these plants would prefer a slightly lighter soil than heavy clay. Prune away any of the spoiled foliage and avoid overhead watering and evening watering if you can. Also be sure nearby plants are not crowding them and blocking air circulation. Finally, you might try making a mini raised bed area for these plants by improving their patch of soil with just a bit of sand and plenty of organic matter worked into it.
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