Probably wouldn't hurt, assuming it doesn't blow away as too light. I suspect its some lack of soil warming caused by the heavy overburden of mulch, and, possibly, lack of water. Its easy to get complacent with that big, thick mulch, in my experience. You might want to consider raking the mulch away from the plants early in the season.

"I'm aware of nitrogen draw down and fertilize extensively with Rosetone, Planttone and Hollytone. "

Have you had a professional soil test recently? Too much fertilizer can look like too little.

I watched while my girlfriend, a 'master gardener', insisted on buying tons bark mulch (and it was still steaming in piles at the nursery, so it was actively decomposing). She (with my reluctant help) spread it all around the beds of her home. Then she planted a bunch of lilies in the beds. The lilies struggled. But the beds looked very tidy with the fresh bark mulch.

I had a couple of tomato plants already planted and they got mulched, too. The leaves began to turn yellow. I finally pulled the mulch away from the stems of the tomato plants and they recovered and eventually produced.

As you have already determined, the problem in not 'Nitrogen tie-up', whatever that is. The nitrogen fertilizer should have cured that problem, right? The problem is that partially decomposed organic material (also known as unfinished compost) contains organic acids that inhibit root growth (and inhibit seed germination. It's how mulch suppresses weeds). Organic acids like Acetic, Oxalic, and Butyric acid are the culprit. Eventually, these acids are converted to humic and fulvic acids which are the end products of the compost process.

Your instincts are very good. Get some finished compost and try that, especially around plants that you want to do well. But you might have a problem with the compost not suppressing weeds the same way that the bark mulch did.

Compost is an excellent mulch and my preferred material for that purpose. It will accomplish the same results as a bark mulch - moisture retention, temperature moderation, weed suppression - but with a much higher rate of nutrient availability. It will need to be refreshed more frequently than a more durable, wood-based mulch and it also offers a pretty fertile seedbed for windblown weed seeds. But they are very easy to remove from the loose mulch if you get them early.

I use about 2"-3" of compost as mulch on my perennial beds and roses a couple times a year and am very pleased with the results. I'm no scientist, but I think the addition of compost adds a whole host of micro nutrients and soil enriching properties way beyond the simple concept of NPK.

I have horses and compost the stall leavings so I have a continuous supply. The only additional fertilizer I have added is the occasional cup of alfalfa pellets around the roses. The compost will break down faster than pine bark so you might not be happy with a one time application if you are expecting it to last all year. While I do get weed suppression from the compost, because it works itself into the soil so much faster that suppression doesn't last as long as bark. But because the compost has done such a beautiful job making my clay soil light and friable weeding is very, very easy.

In my more formal and public areas I sometimes put another inch or two of pine bark fines over the compost to dress things up a bit more. I will also use this combination just around the roses in the late fall for a little winter protection.

Last year a good reliable soil test done by Michigan State
University cost $13.00 per sample and is a good investment. Along with that soil test these simple soil tests might also be of some help.
1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level 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 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.

My favorite mulches are compost, leaf mold, seaweed or hay. I love the look of a garden under leaf mold especially. I mulch continuously---as the materials present themselves.

My favourite mulches are breadcrumbs, pasta, cake, porridge and cereals. I love the look of a garden under cornflakes especially. I munch continuously --- and the materials just present themselves.

How's it going Annpat? Long time no 'see'.

I know! It was just as delightful to "see" you as your post was disgusting to read. In other words---immensely!

idaho_gardener, mulch should never be in contact with stems or tree trunks. It should be a few inches away. It's important to keep bark mulch on top and not mixed in the soil because when it gets mixed in it uses nitrogen as it decomposes.

Lgteacher, did you even read my post?

Yes, you did the right things pulling the mulch away from the tomato plants. I've never heard of anyone using bark in a vegetable garden. Some people use straw. I'm not sure about the accuracy of the rest of your post and will do more research.