We have a beautiful and healthy Anna Rose Whitney Rhodo It is well established - 12 feet wide, 15 feet high and likely over 40 years old. It currently has branches down almost to the ground. The rhodo is on a slope and our soil is sandy and very fast draining. Nothing is growing under this rhodo and rhodo roots are very close to the surface. We are re-landsacaping the yard and have dug up about 10 large sword ferns in order to make room to put in a new patio. The fern roots are between 4 and 6 inches deep. The landscape designer suggests we plant these ferns under the rhodo (after cutting off the bottom 3 feet of branches to reveal the rhodo trunk and the new ferns). I have placed the ferns on the ground under the rhodo and when we hold up the low branches, can see that the landscape designer's suggestion will look very good. The ferns would go close to the trunk, lower plants (like primula japonicas and small grasses) will also go under the rhodo in front of these ferns. Because the rhodo roots are right below the soil surface, I don't want to dig the ferns into the ground and disturb the rhodo roots. I propose to place the ferns on the ground and then place a mulch type soil around their roots and between them. Essentially placing 4 to 6 inches of soil and roots over the rhodo's roots. And because there are so many ferns they will cover perhaps 1/2 of the area under the dripline, specifically the area directly around the trunk. This will bury the rhodo roots under 4 to 6 inches of soil. I am concerned with cutting off air to the rhodo roots. Am I going to effect the rhodo's health by planting a mass of ferns under it?