Q: We want to use a large root ball from a downed tree as a centerpiece for our front yard. What kinds of flowers, or hanging vegetation, would grow well on the root ball? It is about six feet across and five feet high. It also receives a lot of sunlight. Right now, some plants are growing on the ball, but we would like to add more color on the bare spots.
A: What a good idea! My guess is that you’ll need a selection of tough, drought-tolerant plants since the soil on the rootball is not likely very rich.
I might start with seeds of nasturtium near the top. This trailing plant can grow in the toughest situations. If you can make some pockets in the soil into which annuals can be inserted, I’d try portulaca (moss rose). This plant blooms all summer and needs only occasional watering.
If the top of the rootball is flat, you could plant some ornamental sweet potato vines. The foliage of either ‘Margurite’ (chartreuse leaves) or ‘Blackie’ (deep purple leaves) would cascade down the mound of stump, soil and roots. Come to think of it, common morning glory could grow there as well.
Your big challenge will be to water the root ball without washing off the soil. I’d suggest a coil of soaker hose on top of the mound. When watering seems warranted, set the flow of water very low so moisture gradually seeps into the soil without dislodging it.