To cut or not to cut perennials?
What should you do with perennials in the fall? Is it best to cut them back now or wait until spring? If they are left uncut, they will catch more snow and that will provide more protection from the cold. If you have perennials which have winter interest, such as sedum, ornamental grasses, or perennials like black-eyed Susan, or blanket flower which have seed heads which birds enjoy, you will want to leave them uncut.
On the other hand, if you have perennials which are diseased, you will want to cut them down now to 3 to 4 inches and get rid of the stems and leaves. The diseased foliage should not be put in your compost. In compost they may thrive and winter over and be ready next spring to infect whatever plants around which you spread the compost. The 3 to 4 inch stems which are left will also hold snow and any mulch which you put on the perennial.
If you have hostas and have had slug problems with them, you will want to cut off the leaves as soon as they freeze down. The best place for slugs to winter over is in the dead leaves of the hostas. The roots will have taken the energy they need for winter from the leaves by the time they freeze, so the plants can be cut down to ground level. Any debris around each plant should also be cleaned so the slugs can not winter over in it. After the ground is well frozen (usually in November) you can apply mulch to protect the hostas for winter.
The end of September is not a good time to apply fertilizer to perennials because they are shutting down and hardening off for winter, and the fertilizer tends to encourage root growth. It is best to fertilize perennials about the middle of August. Fertilizing in the spring works as well and then the plants are ready for a burst of growth. However, should we get a dry spell, it is important to continue to water perennials until the ground is frozen, not just until the first frost. The roots of perennials continue to grow until the ground temperature is about 40 degrees.
Mulch is important in protecting perennials, especially if they have been planted or transplanted this year. The mulch should be applied after the ground is well frozen usually in November. A foot or so of loose organic material such as straw or leaves works well. Hay is not recommended because it often has weed seeds in it. Mulch will provide 5 to 10 degrees of temperature protection to the soil, which may mean life of death for certain perennials.
Plant bulbs soon
The first week or two in October is a good time to plant tulips, daffodils, hyacinths and other spring flowering bulbs. Be sure to select bulbs which look smooth and feel firm. It is OK if they are missing their papery skins.
Planting depth for small bulbs should be 4 to 6 inches deep and 4 to 6 inches apart. Large bulbs should be planted at a depth of 8 to 10 inches, and 8 to 10 inches apart. If you have many bulbs to plant a long-handled bulb planter or bulb auger will make the work go easier and quicker. Bulbs should be watered immediately, and if the weather is dry, water weekly until the ground freezes. Spring flowering bulbs need to develop roots before the soil freezes in order to come through the winter in good condition.
If you want to prevent bulbs from being eaten by squirrels and chipmunks, you can spray the bulbs with a rabbit or deer repellent, such as Liquid Fence or RO-PEL, before you plant them. Doing this gives the bulbs a nasty smell and taste to discourage these critters. Another way to thwart diggers like squirrels and chipmunks is to lay a piece of chicken wire over the soil after you plant the bulbs. Once the soil freezes, usually the first part of November, apply several inches of mulch to help prevent fluctuating soil temperatures and premature spring growth.
In spring, to protect the new foliage from nibblers like rabbits and deer, give the leaves a bitter taste by spraying them with the same repellent you used on the bulbs. The spray washes off, so repeat after each rain. You may need to switch to other repellents every few weeks, as the critters grow used to the taste.
Kyle Schulz is a Wadena County Master Gardener from Sebeka and the regular gardening columnist for the Wadena Pioneer Journal.