Sometimes it's hard to cram it all in. Plants, I mean. And sometimes, they want something you don't have a lot of--like fluffy dirt.
My first weapon is always mulching--mulch encourages soil insects and microbes who work like little demons for you to make fluffier dirt. But sometimes they just don't work as fast as you need them to, and that's when you need to take things to another level. With raised beds.
A raised bed for perennials is scary easy if you can spare a little cash. First, arrange with a local landscape supply to deliver some topsoil. To get top bang for your buck, you will need to plan to do a couple different beds at once, since they will have to charge a delivery fee. If you have your own pickup, scratch that whole last sentence. Buying bags of "garden soil" at a big box can work, too, but you'll spend at least two times as much for a product that probably isn't much better than a bulk product, if at all. One huge advantage of a bulk product is that it is likely to be locally produced, which means that the soil will be a better match to your existing soil. What THAT means is that your new plants won't immediately draw in their toes when they grow through the new topsoil and hit your old dirt.
But you'd better check first. Go to the landscape supply and "lay hands" on their soil. It should have a varied texture (bigger and smaller grains when rubbed between your fingers) and should smell like good dirt. If you don't like it, go ahead and use soil in bags from the big box.
So, as I was saying before I interrupted myself, it's easy to make a raised perennial bed. Lay down multiple layers of newspaper, hosing them down as you go. Dump new dirt on top. Plant perennials. Mulch. Water. Done. If you have compost, add a smidge, but don't use much. The babies need rest first. I know, they tell you to dig out the grass, mix old and new dirt--hang in there and keep reading.
But what if there's a slope? Or you need a deeper pile of fluffy dirt? It's time to rock and roll.
Garden boulders are any rock at least the size of a concrete block that will stay where you put them. I use a dolly to get them from one spot to another and then roll or flip them into place. If necessary, I'll dig out a depression to anchor them firmly with gravity (especially on a steep slope). You can create a complete ring of stone, a front edge, or a blended approach that has the added soil shallower on one side (another good slope option). Once the rocks are in place you're good to go. Even though the soil will be deeper, still start with a layer of newspaper or cardboard to kill off the grass. No RoundUp, no digging--just pile on the dirt. If by chance you want to plant something larger than your pile of dirt is deep, give it a couple of weeks first. This will let the paper or cardboard get softer so that when you dig that big hole, you can cut right through and into your old soil.
When you follow this procedure, you still need to dig holes appropriately wide and not too deep. Planting deeper than the potted soil will at the very least stunt the growth of your new plant. Which brings me to my final caution: the one place you do NOT want to make a large, deep pile is surrounding an existing larger shrub or tree. Piling up a big pile of dirt around an existing plant will suffocate and kill it. Which is very bad karma.
So pile it up! Just not around your trees. Get rid of some grass and replace it with an easy, beautiful raised bed full of fluffy dirt. Make some flowers happy! You'll smile all week!