We're planning a new shade bed under a large Pin Oak in our Zone 5B backyard. When we bought our house last spring, the area was overgrown with weeds, brush, and landscape fabric (ugh!), but we cleaned it up enough to plant a few things, including a Rhododendron 'Nova Zembla', a few Bleeding Hearts, a Smooth Hydrangea and some Columbine. We had a lot of other projects to get too though, so we weren't able to turn our full attention to it until this year.
It's about a 250 sq ft. space and we're envision turning it into a 'wild'-looking, shaded woodland area, and plan to add several more Rhodo's/Azaleas, Tiarella, Hosta, Astilbe, Fothergilla, Asarum, ferns, etc.
We're going to be sheet-mulching the whole area in a few weeks to make sure we have a nice clean area in which to plant later this spring, and having tested the soil last week, we know that it's already slightly acidic (about 6.2 or 6.3), but most of the plants we have in mind really like an acidic soil, so we were wondering if we need to amend to get the pH any lower?
As part of the sheet mulching process, we're going to add shredded pine bark mulch as the top layer, which may help some, and we were also thinking about adding some HollyTone, just to give some of the Rhodos/Azaleas and other acid-lovers a boost when they go in, but I'm a bit confused about the proper application. The Espoma instructions say to broadcast the product widely across the new planting bed, but should we instead be spot-applying the HollyTone to the planting holes for each plant, and not cover the whole bed?
We've also seen some conflicting advice about timing of application of the HollyTone, with some sources saying that it's best applied when planting new Rhodos/Azaleas, etc., but others saying it's best applied right after they're done flowering...perhaps that's only for established plants though?
Is HollyTone even the right idea, or should we being using a true soil acidifier like Sulfur? Or should we even just hold off on amending now until we get a sense how well everything "takes".
The Nova Zembla we planted last spring is doing reasonably well without any amendments other than compost at planting, and it has shown some growth and increased flower bud development this spring...so maybe we're overthinking things!
Any feedback would be greatly appreciated...thanks!