Fall perennial care can improve the plants’ performance the following year. Cold areas can be hard on some perennials, so putting them to bed with extra blankets may help see them through the cycle of freezing and thawing in northern gardens.
Cutting back perennials conserves the energy they would expend producing seeds. Leave at least 2 inches of stem, and remove all faded flowers, dead leaves and stems, as these can help eliminate pests that winter over in dead growth.
Put down at least a foot of loose mulch, such as straw, at the base of your perennial plants. This should be done in late fall in the north to give plants time to harden off. Mulching provides 5 to 10 degrees of protection to the soil, and also replenishes nutrient supplies.
Perennials prone to overcrowding, such as irises and daylilies, should be divided every 3 to 4 years. This not only gives the established plants a boost, but it also produces more new plants to fill in other bare spaces in the garden.