|What ground cover will survive in densely shaded area containing tight fine roots of a box elder tree? The area receives little moisture during droughty summer months. Would purple wintercreeper be hardier than bishop's cap (bishop's weed), which did not thrive? What would you recommend?|
|There are two distinct plants with the word Bishop in their common names -- Bishop's Weed (Aegopodium) and Bishop's Hat (Epimedium). Aegopodium is extremely invasive and would be likely to grow in the conditions you have described. In my experience, It is so invasive that I would never suggest anyone plant it. It will spread by creeping roots and also by seed, and is nearly impossible to eradicate should it spread to an area where it is not wanted. If this is what you planted, it may come back with the rains next spring.
Epimedium, on the other hand, is a well mannered plant often suggested as a ground cover for dry shade. In my experience, it does need adequate moisture in order to become established and really does best where there is no summer drought. It spreads very slowly, particularly where moisture is low, but is ultimately an elegant garden plant. If this is what you planted I am not surprised that it did not survive in that situation.
The Euonymous fortunei group consists of a number of semi-shrub, semi-vine plants, and they are indeed very tough. The purple wintercreeper would be a good one to try. Another plant to try might be plain old English ivy (Hedera helix) as it is also extremely resiliant.
You will need to prepare planting holes for each plant by removing the immediate tree roots, amending the soil, and then watering the new plants so that they have a chance to become somewhat established before being asked to battle the tree for moisture, nutrients and light. To this end, a top dressing of compost and a layer of organic mulch over the area would also help improve the soil over time, and improve the growing conditions.
Finally, if the area is essentially bare, you might consider simply using an attractive layer of rocks or large chunked bark mulch set over a permeable weed barrier fabric to keep the dust down and look tidy rather than trying to establish a planting. Good luck with your project!
Good lcuk with your project!