Plum Tree causing problems?

I have an 'ornamental' plum tree growing in my patio (not sure of the exact name/species as it was here when I moved in). Outside of the patio, on the other side of a fence, is a raised garden. I am having problems over-wintering anything in the area of the raised garden immediately on the other side of the plum tree.

Two years ago, I dug everything out of the raised garden, ammended the soil with peat, sand, and compost, and planted tulips and daffodils. The next spring, all the bulbs came up and flowered, except in a 2' area directly opposite the plum tree in the patio.

Last year, I planted hollyhocks all along the back edge of the raised garden, next to the fence. Again, most of them came back this year except in that same 2' area directly opposite the plum tree in the patio.

I have no problems growing annuals in that area - they thrive and grow just as well as in the rest of the raised garden.

Has anyone ever had problems growing plants near a plum tree? Can you offer any explanations, or solutions?

Thanks!
Jeannie

Here is a picture of a Veronica plant, started last summer, that is growing in the raised bed, but outside of the 2' area opposite the plum tree:

And here is a Veronica that actually made it through the winter planted in the 'dead zone'. Notice that it is not only smaller, but the leaves are darker and mis-shapen.

I don't think plums typically cause problems for plants growing under them--only exception would be right underneath it you might have trouble with things that like wet shade since just like any tree they will tend to take a lot of the moisture. Is the area where you're having problems even in the root zone of the plum tree? It sounds like there's some level of separation so I'm wondering if the roots even go that far. And if they do go that far, I suspect there's a bit more of the raised bed that is also in the root zone of the tree than just that 2 ft area, and if it's the tree that's causing the problems then you should be having trouble everywhere in its root zone not just that tiny area. Is that area a low point in the raised bed by any chance? Staying a bit extra wet during the winter could cause things to be less reliable about coming back. Maybe if you could post some pictures of the whole area that would help too.

You go up four stairs from the ground level to get into the patio, so there is no level separation. Here is a picture of the raised bed. The plum tree is just on the other side of the gray fence, about half way down. As you can see, the raised bed is fairly level.

I still really doubt if it's the tree--if it's that close to the bed, then its roots go under more than just that 2 ft area so the problems should be more widespread. And you would also be seeing problems year-round--if plums did have allelopathic properties it would cause things to struggle and not do well all year round, not just over the winter. Plus I don't think plums cause that sort of problems anyway.

I'd still look at the moisture, even if the bed looks fairly level maybe that area is slightly lower, or maybe the composition of the soil is a little different and retains more water. I'm sure there are other possibilities too, maybe a critter just happens to have easier access to that part of the garden, or maybe it's just a strange coincidence. You might also consider having the soil tested to see if there's something different between that part of the bed and the rest. Or think about what else goes on in that area during the winter that might be different in that particular spot--is it more exposed to wind? Salt?

Thanks, ecrane, you have given me a lot to think about. I had never heard of plum trees causing problems (like walnut trees do), but can not imagine what else coud be the cause.

I think I will look into soil testing. Maybe some neighborhood ne'er-do-well has dumped something onto that spot!

I used to have a spot where a plant would live two years and then inexplicably die. It didn't matter what I planted. The same kind of plant sighted elsewhere would do just fine. Two years and dead. Finally I gave up on that 3 x 3 spot and let it go to grass. Then we decided to dig a big koi pond 3-1/2 ft deep. The old problem spot was in the pond excavation area. And what do you know! Previous occupants had buried an old "burn barrel" there. It used to the custom in the 50's to burn your trash in an old barrel. It was about 20" below the soil line. The krud we dug up was ubelievble. Lots of aluminum foil, well you can imagine. Besides that we found a complete set of busted up concrete steps, about two bushel baskets of broken ceramic tile and about a wheelbarrow load of stone. The stone was buried in one spot. I even found what looked to be an old lamp! The first owners apparently didnt haul anything away. They just buried it. I don't know who they were. But I sure would like to give them a piece of mind. After the pond excavation ordeal I made a practice of digging a test hole of least 24" before I planted anything new. I have never found another thing. Thank heaven.

LOL!!

When I amended the soil about two years ago, I dug down about a foot or so - maybe I need to dig deeper?

maybe you should try using a metal detector thingie instead of doing all that digging!?
I'm not sure how deep they can read though?

I'd go for that except they don't pick up concrete steps or broken ceramic tile or any other nonmetallic object. Yesterday I was digging in a bed prepared years ago and I found several of those little green plastic soldiers and a miniature blue metal airplane. The paint had retarded the corrosion on the airplane somewhat. I never know what I'm going to find out there.

lol sounds like a big mess!
Our previous owners had a buried rock pile, with some trash, but so far nothing like that, at least that I've found.