Q: I have a few English Bluebell plants in my garden. Their leaves are now flat and yellow. What if anything is wrong with them?
A: I am not sure what you mean by English bluebells. Virginia bluebells (Mertensia virginica) are early blooming spring flowers in this region. They are a spring ephemeral, meaning they come up and flower in the spring and then die back to the ground later in the season. Most bluebells have yellow leaves now and eventually they will die back completely until they come up again next spring.
A reader responded to this question with information about English bluebells. The Latin name is Hyacinthoides non-scripta. She noticed at Winterthur last week they had both Virginia bluebells and Spanish bluebells (Hyacinthoides hispanica), and the latter look almost exactly the same as the English ones. She tried for years to get Virginia bluebells to grow in her suburban Wilmington garden without any luck so finally gave English bluebells a try and they have been great. They have beautiful blue flowers that last for several weeks in the spring. In her garden, the flowers are now past, but the foliage is still bright green, though mostly flatter than upright at this point. They will go brown later on and fade away as do the Virginia bluebells, but it does seem early for them to be turning yellow. She ponders — perhaps it depends on location and amount of sun, since they will grow from full sun to full shade, and mine are mostly in shady places.
My response is this confusion is often the problem with common names. I know that plant as Endymion non-scripta and have called it scilla as a common name. I see that Hyacinthoides is the correct scientific name. I still think it is more likely that Virginia bluebells (Mertenisa virginica) would be turning yellow now and fits the description of large flat leaves. Hyacinthoides has narrow linear leaves. Both plants are great in the garden!
Q: Please help me to identify this very sweet smelling bush that is growing near my home.
A: The shrub in question is Elaeagnus umbellata or Autumn olive. It is very sweet smelling, but it is an exotic invasive species and should be removed. It invades natural areas and displaces native species. Here is a fact sheet about autumn olive. http://www.invasivespeciesinfo.gov/plants/autmnolive.shtml
Q: I have several Berberis thunbergii “Aurea” bushes planted on the south-east facing side of my house. They suffered what looks like frostbite from the ice storms we had this past month. Will pruning this spring bring them back to health or do I have to treat then with some kind of solution?
Also I have a row of 20 arborvitae on the north facing side of my house that seem have suffered the same kind of damage near the bottom of each plant. Only the very bottom branches of the trees have turned brown. They are all about 7 or 8 years old. Again, do I need to treat them with anything or should I cut the brown limbs off?
A: There is nothing you can apply to correct winter damage. The only solution is to prune back the dead or damaged tissue. With the barberry, they can be pruned hard and they will grow back. But, remember Japanese barberry is on the invasive plant list in Delaware. Maybe you want to take this opportunity to replace them with a better plant. Here is a publication that lists alternatives to Japanese barberry (http://extension.udel.edu/lawngarden/files/2012/06/PLD.pdf). The lower limbs of the arborvitae should be pruned, but they probably won’t regrow at the base of the plants.