Basic Perennial Care

Although perennials are plants that come back year after year, they do require care for good performance. The first consideration is selecting the proper site, or suiting your plant selection to your site. Most perennials require fertile, well-drained soil, with full or at least partial sunlight. If you have shade, wet soil, a very dry site, or other special conditions, your Cooperative Extension or gardening books should help you with suitable plant selection.

You should also have your pH tested - that is, soil acidity or alkalinity, because most perennials require an average pH but others have particular requirements. You can amend pH if needed - but it is always easier to work with the soil you have, using compatible plants.

Soil preparation should be done before planting perennials, but if you are working with an existing bed, you can continue to improve soil by adding organic matter each season. Simply work in compost, grass clippings, or chopped leaves - into the top few inches of soil without disturbing plant roots. Also, an organic mulch on the soil surface will add organic matter to the soil gradually, as it breaks down, while it controls weeds and maintains soil moisture at the same time.

Fertilizing perennials may be done in several ways. Some add a balanced fertilizer such as 5-10-5 to the soil each spring, at a rate of about 3 pounds per 100 square feet of garden area. Be careful never to touch the plants with synthetic fertilizer. Gardeners with rich soil, high in organic matter, and perhaps access to aged manure, may never need to add commercial fertilizers. However, you may add rock phosphate or bone meal every 3 to 4 years to ensure root growth and bloom.

Deadheading - the act of removing finished flowers - is important to good perennial gardening. Many plants, such as candytuft, perennial geranium, and coreopsis, can be cut back drastically (to 4 or 6 inches) after bloom, to encourage re-blooming later in the season. Most perennials should be cut back in the fall once they have browned or been frost-killed. The removal of debris helps to minimize the spread of disease. On the other hand, plants with winter interest such as perennial grasses, African daisies, or coneflowers are best left standing to decorate the winter landscape. Most perennials benefit from leaving up to 6 inches of stem and foliage to protect the crown. Remaining plant debris is removed in spring.

Winter mulching is important to protect your perennial collection, particularly where there are patterns of freezing and thawing, which cause heaving of the roots - which dries them and kills the plant. In fact, to prevent winter desiccation, most perennial beds should have good fall rains (or watering to replace them) before the hard freeze, followed by a 3-inch protective mulch of chopped leaves, straw, or wood chips.

Finally, basic perennial care involves weeding, which is an on-going process, and dividing when the plants become overcrowded or fail to bloom in the center of the clump.