A good site selection cures many ills.
If you’re a beginner, start small. You can always make the garden bed bigger if you are really crazy about gardening. If your interest wanes – or if some unexpected life event comes up that makes taking care of your garden difficult – then the garden is still manageable. It’s easier to expand a garden than to make it smaller. Also, gardening is easier if you’re not overwhelmed by it. Trust me.
When you are placing your garden, don’t forget to put it in a place where you can see and enjoy it. Look through your kitchen window, consider the view from your deck or upstairs window. If you can place it where you can easily look out and enjoy it, you’re in business. Bonus points if you can place the garden close enough to a window so you can plant a fragrant rose right there and enjoy the scent.
If you’re just starting out, you’ll need to figure out what your garden spot has to offer. Is it a shady spot or sunny, or a mix of both? To better understand what that area provides, look at the plants growing there right now.
If you see a bunch of lush grass growing thickly in the sun, that tells you that that this is a full-sun location with fertile soil. If you see ground ivy or English ivy, or grass that’s sparse because of the shade, then use that area for a shade garden. If there’s nothing growing there because the shade is too dense, you’d better find another spot for your plants, or trim off some limbs to let in some more light. Use your observations to find the best plants for the site. Some perennials love full sun all day – some love the shade – some can take a bit of both.
Also, look at how much water the area gets. Does water linger in puddles here long after a rain? Or, does it seem that you can never water this area enough because the soil is so sandy? You can fix clay soils and sandy soils by adding compost. If your soil is especially problematic, install raised beds and fill them with potting soil and compost, then plant.
Check the drainage of the soil. Dig a hole six inches deep. Fill it with water. If the water drains away within the hour, then you have good drainage. If not – or if the water won’t drain at all – then you might consider installing raised beds for your perennials. (Note: Obviously, if you’ve already had a ton of rain, or if it’s flood season, this test won’t be much good.)
If you do have a puddly place in the place where you’re dead set on having a garden, you can either fill in the hole with some good compost, or make the best of a bad situation by putting a birdbath, small water feature, or even make a mud puddle for butterflies to drink at and add in some butterfly garden features there.
As you’ve making notes, look at the slope. Ideally, the ground should slope from the middle of the garden down to the front, so that water will not puddle right in the middle of your garden.
If you are planting on the side of a hill, consider how to set up the garden to keep erosion to a minimum. I don’t know if you’ve heard of terrace farming, but it’s a kind of way farmers set up their field to keep erosion to a minimum. There are no uphill or downhill lines in these fields – only horizontal lines, or furrows, or terraces. Follow the same setup in your garden, setting it from one side of the slope to the other, instead of going straight down the slope.
If the slope is very bad, groundcovers are a possibility. If you are a determined sort, an alpine garden would be a possibility here, so you still can have your perennials AND you will have good erosion control, and one less slope to mow (and fall down). So there is that.
If you’re planning to take out those old yews and barberries, or whatever shrubs were put in for foundation plantings, be prepared for a little heavy work. Digging out an old yew takes a lot of digging, to get down under the roots far enough to cut it out. When I was working in landscape installation, there was one particularly large yew that just would not come out. We’d dug a hole that was a good three feet wide and the roots were wide and thick. I believe a pickax was involved in this operation, various saws, and even then we had about three people rocking the stump back and forth. We’d lean it as hard as possible to the right, and try to saw out what roots we could get from that angle, then we’d lean it hard to the left and repeat the operation.
Finally we managed to wrest that thing out of there and there was celebration all around, and possibly some after-work beers, which were more than well-deserved. So, in short, yew bushes can be a bear to deal with. If you’re buff and tough, and you don’t mind a lot of digging, AND you have a good quality saw, then knock yourself out. (Not literally – I hope.) Otherwise, hire a contractor to do this.