Perennial flowers are a bit different than annuals. They generally require less fertilization and since they often slow down growth in autumn to prepare for dormancy, fertilization should be avoided after late summer.
Fertilize your plants, shrubs, trees and lawn to stimulate root growth, which will help your plants survive the winter and recover earlier in the springs. Fertilize perennials in the early fall for extended life. Fertilize trees and shrubs in the late fall to give them a boost before the winter.
Make the last fertilizer application before July 1.
New growth also needs time to "harden off" before winter. Tender new growth is at risk of cold injury if it is forced late in the season, when plants and trees should be shutting down for winter.
Michigan State University Extension advises to not fertilize perennials in late summer or early fall. This may cause the plants to flush-out additional growth that will not harden-off in time for an early winter freeze.
August is an ideal time for gardeners to give their plants a boost into the later stages of growth. Many people who are just learning how to garden at home overlook the benefits of fertilizing their plants.
Beginning late summer and through September and into early October is a great time to fertilize many plants. This includes lawns, young trees, shrubs that need to grow more leaves and groundcovers that need to spread and cover.
Fall Fertilizer Timing
For the majority of cool-season lawn owners, apply fertilizer anywhere from September through early November. The further north you garden, the sooner you'll feed your lawn. Fine-tune the timing for your locale by talking with your local extension service or garden center.
Timing: Apply fall lawn fertilizer once between August and November, right before winter hits, 6 to 8 weeks after the summer feeding.
Perennials: Rake away mulch in spring and apply 1-inch of compost around plants. Lightly fertilize plants if needed with a complete granular fertilizer. This can be repeated mid-summer if growth is weak or foliage is light green in color. In late summer, fertilize plants that will bloom late summer through early fall.
Water and Feed Your Perennials
You can easily water and feed at the same time with Miracle-Gro® Liquafeed®. When watering, avoid perennials' leaves to prevent disease, and aim for a soil consistency that is neither too wet nor too dry.
In most regions, October is not too late for fall fertilizer, and you can even put fall fertilizer down in November in many places.
Broadcasting a slow release fertilizer is the best choice to meet season-long plant nutrient requirements, but you can also use a balanced fertilizer such as 20-5-10. If your soil test indicates that you do not need phosphorous, choose a product such as 20-0-10.
Some perennials, like hostas, peonies and daylilies, need to be pruned in fall to avoid winter damage. Plants like these should be pruned after the first few frosts in late fall or early winter. Other perennials like mums and coneflowers are better off being pruned in spring just before new growth comes in.
It's common to think that everything should be chopped down to the ground in the fall, but some perennials actually need their foliage to protect new shoots through the winter. Other varieties offer up important habitat for local wildlife and some perennials provide height and interest through the winter months.
Perennials that require minimal fertilizer include ornamental grasses, false indigo, asters, sea holly, bee balm, and butterfly weed. On the flip side, some do better with extra nutrients. Heavy feeders include mums, lilies, lupines, tall phlox, peonies, delphiniums, and astilbes.
It does not need much fertilizer; however, if your soil is not in good shape or the plant is not thriving you may need to feed the plant. Rich soil and a lot of water is just as important for hosta health as is fertilizer. New hostas planted in the spring will need a good starter fertilizer to help establish the roots.
Spring Perennial Plantings:
Week 1: Every day to every other day. Weeks 2-3: Water 2-3 times per week, depending on environmental conditions. Weeks 4+: Water 2-3 times per week, more in hot/dry conditions. When cooler, water less.
While this fall lawn fertilizer dose is important, an application at the end of October or early November is essential. At that time, apply a fertilizer with a formula of 13-25-12. The push of phosphorus will stimulate root growth through November and even into early December.
The November fertilizer application is the second most important time for cultivating a cool season bluegrass or tall fescue lawn, with September being the most important application. The November application helps the lawn flourish in several ways.
While the best method for determining exactly how much fertilizer is needed is a soil analysis conducted by a laboratory, most cool-season grasses require 2 to 4 pounds of nitrogen per 1,000 square feet each year, and a majority of this nitrogen should be applied in two fall applications; one in September and the other ...
You should fertilize your lawn a day or so after a light rain or using a sprinkler. This prevents the application from being washed away. The moisture gets your soil damp and ready to receive nutrients. Do not apply fertilizer before or after heavy rains.
If you have an automatic sprinkler system, you should fertilize your lawn about every six weeks. You don't want the watering to outpace the fertilizing as that could negatively impact the lawn's growth cycle. If you don't have a sprinkler system, you can wait an additional two weeks between applications.
It really depends on where you are and what kind of grass you have. Late fall may be better than winter for colder regions. The absolute best time to fertilize your lawn is just before the expected frost date. The goal is the same when you feed grass in late fall or winter as it is with dormant plants.