First, take a good look at what is there so you can make a reasonably intelligent decision about what is needed. These simple soil tests may be of some help.

1.Testing for organic matter. Put about 1 cup soil (enough to fill the jar to 4 inches) in a clear 1-quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 1) Soil test for organic material. From that soil sample put enough of the rest to make a 4 inch level inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1-foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains’ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell, to a point. Too much organic matter can be bad as well.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

More than likely that "native" soil just needs a lot of organic matter.

It depends on what is in there in relation to what you want to grow. All we can see is the top of it, which looks very dark as though compost or other organic amendments have been added. If the whole thing looks like that when you dig into it, I see no reason to dig it out and replace it.

Dig up a shovelful or two and tell us whether it's sand, silt or clay, and how much organic matter is in it. A pic would be even better.

I am not sure what is wrong with your plant but it may or may not be soil related. If no one here recognizes it you might want to post in the Garden Clinic and/or somewhere else appropriate to that plant.

Is this area dry or soggy, which direction does it face, and where on Planet Earth are you located?

If you do want to replace some or all of the soil, don’t buy bagged stuff from big box stores. Trust me...I did that originally. Over the years, it clumped together and didn’t allow the roots to grow freely. When I redid my garden last year, I used topsoil/compost mix from a local mulch supply company that is actually cheaper and way better for the plants.

i would still follow other recommendations before replacing soil, though.

toxcrusdr: I've added my location to my profile name. The garden strip gets no direct sun; it is under the eaves of my house. Runoff water from the rubber-tile-covered concrete slab is the only water the garden strip gets. The plant faces East.

"The garden strip gets no direct sun; it is under the eaves of my house. Runoff water from the rubber-tile-covered concrete slab is the only water the garden strip gets."

Coprosma is just the wrong plant for this location.....it wants all the conditions that this space does not/cannot offer!!

Back to the dawing board!!

My Coprosma has been growing fantastically in this location with those conditions for 20 years. I keep it pruned to about 2 feet tall so it doesn't block a window and so it doesn't encroach too much on the patio It's been sick (and dying(?)) in the last 5 months.

Gary, I don't know how to explain it more clearly but that is the wrong plant for that location :-) As a professional landscape designer and consulting horticulturist with several decades of experience, I can state very certainly that the phrase 'right plant, right place' has a great deal of validity to it........and that is not the right plant for that place!!

But feel free to do whatever you like - you asked for advice and were given it. What you choose to do with it is up to you.

Side notes... if your home is built on a slab foundation (no basement).. you might run into gravel/stone not too deep under the top soil that surrounds the house 6-8”. This is how it is around the garage portion of my home. That soil dries out quick and nothing enjoys living there for me without floundering.

If you have a basement, then in my option .... you wouldn't run into any bathtub effect since the water will drain down. At that point, you could dig up and replace or mix in nice amendments. It would function like a container plant in that small strip.