Fall is the prime time for fertilizing the cool-season lawn grasses we grow our region. But to minimize pollution of waterways, consider having a soil test done first. If it shows that levels of phosphorus (P) and/or potassium (K) are adequate, choose a fertilizer that contains nitrogen (N), (the first number in the fertilizer analysis) and little or no P and/or K (the second and third numbers in the analysis). If you're using a chemical fertilizer, choose one with 50-70% of its nitrogen in slow-release form. Apply at the rate of one pound actual nitrogen (the N number indicates the percentage of actual N in the fertilizer) per 1000 sq. ft. two weeks after your last mowing, usually around Thanksgiving. If you're using a fertilizer with a natural, organic source of nitrogen that needs warm soil for microbial activity to releases this nutrient, apply it earlier in the fall, around Labor Day.
Now is the time to plant garlic for harvest next summer. Both hardneck and elephant garlic are adapted to our area. Plant individual cloves, root end down, 2-4 inches deep and 4-8 inches apart, in well-drained soil into which a couple of inches of compost has been incorporated. Once the ground freezes, cover the garlic bed with 6 inches of straw or shredded leaves for insulation.
Plant an Amaryllis Bulb
For dramatic winter time flowers, pot up an amaryllis bulb this fall. Set the bulb in a container that is only a couple of inches larger than the bulb's diameter, and place it so the top third of the bulb is above the soil level. Water well, then place in a cool (60 F) spot until you see a tongue of green emerging from the bulb. Move it to bright windowsill, keep soil lightly moist, and feed every 2 weeks with a balanced houseplant fertilizer. You should see blossoms about 6-8 weeks after planting.
Leaves Seedheads for Birds
When cleaning up the flower garden in fall, leave some the seedheads to feed the birds. The seedheads of plants like purple coneflower (Echinacea), black-eyed Susan (Rudbeckia), coreopsis and cosmos will provide a tasty treat for birds such as goldfinches.
Pinch Brussels Sprouts
To get the sprouts to ripen together, pinch off the top couple of inches of your Brussels sprouts plants to direct their energy into the sprouts that are already developing along the stem. Unpruned plants will continue to produce new sprouts until the weather is quite cool, though they may be smaller. Clip off any lower leaves that have yellowed, and keep plants watered if fall weather is dry. Sprouts harvested after the first frost will be sweetest. Harvest from the bottom up when the sprouts are between 3/4- 1 1/2 inches in diameter.