Why are many of the leaves on my Lemon Lace shrubs turning brown.
Many of the leaves on my beautiful Lemon Lace shrubs are beginning to turn brown, as if they're drying out? However, the soil is well drained and moist all of the time. Could it just be that we're entering the dog days of summer and they are suffering from heat stress? Or is it something else? The brown turning leaves are dry and crunchy.
Denver County Colorado elderberry
It looks from your 3rd photo like the leaves may be starting to discolor and die on the interior of the shrub. That often suggests the roots are being overwatered (vs. under-watered). My recommendation is to check soil moisture. You write that the soil is 'moist all the time' but perhaps it is too moist.
The timer might have been set high when the shrubs went in to get the plants established but now needs to be dialed back a little, or, if your shrubs are being watered by drip emitters, the placement of the emitters may need to be readjusted and backed off the crown of the shrub. It is very important to feel the soil at the roots with your fingers to assess moisture and not simply rely on the irrigation system to get it right.
It's also possible there may be some scorching going on, particularly if your shrubs are new. It has been relentlessly hot and dry with very low humidity on the Front Range and, while the 'Lemony Lace' cultivar of Elderberry (Sambucus racemosa) is grown for the pretty yellow coloration of the leaves, that same trait may make the selection less adapted to a hot, sunny, western site.