Fall is time to fertilize spring bulbs

The sunny days and mild temperatures have helped make fall gardening chores rather enjoyable. Many gardeners are finishing up those outdoor chores in anticipation of the approaching cold weather. So, if you are making a last-minute check list, here are a few suggestions to help you put your flower beds and vegetable gardens to bed for winter.

Fall is a good time to fertilize spring flowering bulbs. Roots gather and store the nutrients for winter. Then, next spring, all that energy is used for flower development. If established bulbs have been fertilized in the past, there is usually enough phosphorus and potassium in the soil.

However, it is best to take a soil test to be sure. If the soil needs phosphorus or potassium, use a complete fertilizer such as 10- 10-10 or 13-13-13. Apply it at the rate of 2.5 pounds per 100 square feet or one rounded teaspoon per square foot. If phosphorus or potassium are not needed, blood meal makes an excellent fertilizer. It should be applied at the rate of 2 pounds per 100 square feet or one teaspoon per square foot. Turf fertilizers such as a 27-3-3 or 30-3-3 can also be used, but the rate would be 1 pound per 100 square feet. When using turfgrass fertilizers, make sure there are no herbicides or insecticides in the product.

In the past, you have probably heard to “clear cut” dead flowers during the fall to help control insect and disease problems. However, with herbaceous perennials that have been pest free, you might consider leaving them to provide structure, color, cold protection, and wildlife habitat during the winter months.

For example, ornamental grasses can be attractive. Their long graceful blades flow freely in the winter winds. Likewise, a light snow gathers on the leaves to form a frozen fountain. Be cautious however, those near structures should be cut to the ground as they can pose a fire hazard.

Perennials with evergreen or semi-evergreen foliage can also provide interesting color. Foliage left on marginally hardy plants such as mums and tender ferns provides insulation and helps ensure overwintering of plant crowns. And seed heads of some plants such as purple cone flowers and sunflowers supply food for birds. Of course, some perennials are naturally messy after dormancy and should be cut back in the fall. Trimmed materials should be added to the compost pile. If available, add some green material as well. The nitrogen source will help decompose the tough woody stems.


Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.