Top dressing/applying compost works just fine.

It takes a little while, but in most areas water/worms/microbes/animals/gravity/etc does it's thing and works what you put on top down a few inches in the existing soil. In many areas you can see a difference in the top few inches of soil in just a season or year.

While it's busy working it's way deeper into the existing soil improving it's physical properties, the water/rainfall from the top leeches nutrients down into the existing soil keeping it around in the root zone a while...added benefit.

Side dressing, carefully placing compost, or what ever, next to or near to the existing plants but not on top of them will work. You would not want to cover the growth crowns of the existing plants.

Alfalfa tea is a great fertilizer for perennials. I also bury raw kitchen scraps between my perennials. Both of those methods encourage earthworms who leave the best fertilizer there is - worm castings.

Always use an organic mulch such as shredded bark which will gradually break down and improve the soil. If you have grass clippings they work really well as the worms like them.

Here's a pic of my garden after 3 weeks of neglect last summer. Fortunately it rained but I hadn't done any fertilizing or any care. Just years of regular application of alfalfa tea, compost, and mulch.

Thank You NC-Crn, Kimmsr, and Luckygal. I will take all of you advice into considertion.

Luckygal, your garden is beautiful.

I'm a big believer in mulch... Aside that, just top dress with compost.

Top dressing may smother the plants, especially if they are growing when top dressing is applied. Side dressing, putting the compost or other material along side the plant, is a better choice since that will not cover the plant.

Every spring I cover the beds with 4 inches of composted leaves. In July I add 2 inches of shredded limb mulch. Then in October I add two more inches of shreeded limbs. The soil in my beds had changed from haed red clay to porous, black, rich soil as a result. In the spring I usualy clear away the mulch from directly touching the plants, creating a depression around the plant.