I am in Western Washington, zone 7b. I have 2 problem sites (well, problem for me anyway) for which I would be grateful for some help.
Both sites are shaded to west by 15' of Arbor Vitae, so direct sun until early afternoon. Soil is generally acidic, but amendments can be made. I would like to put fruittrees in both sites, with a preference for Persimmon and Asian Pears if they would work.
1. Wet soil area - during rains any hole will fill to within 6" of the surface. Two mature Cherries, Camelias, etc seem to do OK in that area, but I am concerned with a new tree. I am thinking about an Asian Persimmon (Saijo - relatively reliable fruiter in our area) as I believe they are reasonably wet tolerant.
2. Old Blue Spruce area - the Blue Spruce has gone, a combination of it shading a large swathe of the garden and becoming a view blocker for neighbors. However, during it's life any veggies growing nearby were stunted, but only within about 4' of the drip line. From what I have read it is the needles of the BS that are allelopathic, which kind of makes sense given the limited radius of the perceived impact. At any rate I want to plant in that general area with a couple of smaller (15') trees but I am wondering if I need to put in some allelopathic buffers (mulberry??) or should I just plant away? Thinking either American Persimmon or Asian Pears.
Thanks for any thoughts. If Persimmons and Pears will have issues, then what fruits could be suggested?
I was just trying to bring the possibility of a bush layer into the conversation, that could be planted between fruit trees. I'm not really sure if your desired fruit trees will succeed in the places you mention, sorry. Don't have enough experience on the matter.
For the wet soils area, persimmons and pears with Pyrus communis rootstock are considered acceptable. Is there any possibility of doing hugel beds where the trees are going to be planted, maybe even mound the planting site to give the roots more area above the water line? Remember, when planting a tree that doesn't like wet feet in a wet area, it's always easier to plant above the water than to figure out a way to keep the water out of a hole that you dig. The hugel bed would help to regulate the moisture levels, also.
As far as the spruce area, while there are some studies that show that spruce needles as a mulch can reduce germination rates, it seems to be plant specific. I personally feel that this probably has more to do with greatly increased acidity of the soil than an allelopathic compound released by the spruce tree. Have you done any soil tests of the area? If the tree is gone, you could get decent results from throwing a little lime around the area for a quick pH adjustment, then incorporate lots of good compost into the area which will help to maintain positive pH levels while the plants grow.
From http://www.edibleforestnursery.com/SOILINFO.HTM :
pH: Alkaline soil (over 7.5 pH) makes iron less available causing the leaves to yellow. Pome and stone fruits do fine in most acidic soils (down to a pH of about 5.0 or a little less) but acid soils make some minerals less available (calcium, phosphorus, and magnesium) and others overly available (such as aluminum and manganese) So if your soil is over 7.5 add an acidifier such as sulfur or an acidic mulch. If it is very acid, add lime. See your extension agent for amounts.
Hope some of that might help you.
"Instead of Pay It Forward I prefer Plant It Forward" ~Howard Story / "God has cared for these trees, saved them from drought, disease, avalanches, and a thousand tempests and floods. But he cannot save them from fools." ~John Muir