Gardens grow and change, and that is part of their beauty, but what do you do when your garden is past its prime? You do not have to remove all of your landscaping and start over, but keep in mind that it will take some time to rejuvenate an overly mature garden.
My own home came with an array of overgrown quince, spireas, irises and daylilies. The thought of trying to start over was discouraging to me, but a little bit of patience is bringing these plants back to life.
The flowering quince in the front yard was more than 8 feet tall a few years ago. Following basic pruning rules, I cut it back as soon as it has finished blooming each spring and take care to not remove more than one-third of the plant at a time. Dead or diseased branches are removed first. I also try to always cut back to another branch or to a bud, because the cut ends will die back to these points anyway.
Lilac and other spring-flowering shrubs should also be cut back after blooming. Pruning will stimulate new growth, bringing the plant to a more vigorous state. Remember to not remove more than one-third of any tree or shrub at one time. Returning a plant to a healthy specimen may take several years of repeated pruning.
Summer-flowering shrubs like bridal wreath spirea should be cut back in late winter or very early spring in the same manner as the spring flowering shrubs. The newer dwarf spireas can be cut at this time; I like to wait until I see the first buds on their branches.
Some sources mention cutting shrubs back to the ground periodically. This can cause serious stress for the plant, and new growth may be spindly and unnatural in appearance. Shrubs that die back to the ground in winter like butterfly bush are the exception.
Once the shrubs have returned to a healthy condition, only light pruning each year is needed to maintain vigor. If the plant is too large for the space, remove it and plant a species with a smaller mature size.
Evergreen shrubs like yews and junipers can be more difficult to rejuvenate. If they have been pruned with hedge clippers, you will need to take special care to remove the "birds' nests" of branches that are left. If needles in the center of the plant have fallen off, it is unlikely that more will ever grow from the branches. If the top was cut wider than the bottom, the lower part of the shrub may have shaded itself and dropped lower needles. Be content to work on these plants slowly.
Most perennial flowers should be lifted and divided periodically. Dig up the plant and cut it into sections. Hostas and daylilies may require a sharp shovel or even an axe to split apart. Coral bells and irises can usually be pulled apart by hand. Most irises and daylilies can be divided after blooming, while other perennials are best done in the fall or early spring. Give the extras to a friend if you don't have the space to replant them.
Dividing perennials can also be an opportunity to add organic matter to your soil. Work with a section at a time, digging perennials and tilling in compost before re-planting.
If your trees are now shading the sun-loving plants (or vice versa) in your garden, move the plants back out to a sunnier area.
Remember that gardens age just like people and can end up looking a little tired. Don't think that you have to start over, but be prepared to do a little work to get your garden growing like new.