Many experts suggest waiting until the spring when there have been several days at 50-degree temperatures to thoroughly clean-up plant material in your yard and garden. This offers enough time for any of the insects overwintering to emerge and move on before they are forcibly removed.
Delaying your garden's clean up until the spring is a boon for all the creatures living there. Instead of heading out to the garden with a pair of pruning shears and a rake this fall, wait until the spring temperatures are in the 50s for at least 7 consecutive days.
The best time to start your fall garden preparation is after the first few freezing nights have killed back much of the flowers and foliage on the plants.
Hold off on your spring garden clean up until daytime temperatures consistently reach the 50s, if possible. Scores of beneficial insects – ladybugs, assassin bugs, and damsel bugs, for example – hunker down for the winter in leaf litter as adults. Others do so as eggs or pupae.
Soil testing, removing plant material and adding organic mulches, compost and cover crops are all smart gardening techniques for fall cleanup. Use shredded leaves raked from your lawn to cover vegetable gardens or beds.
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.
Micro-organisms are the life of soil, and they need food and nutrients all the time. The more leaves left on your garden, the more feed for these micro-organisms that make soil healthier and plants grow stronger. As the leaves decay, they add organic matter back into the soil, which lessens the need for fertilizer.
Also, do not cut back hardy perennials like garden mums (Chrysanthemum spp.), anise hyssop (Agastache foeniculum), red-hot poker (Kniphofia uvaria), and Montauk daisy (Nipponanthemum nipponicum). Leave the foliage. It's important to protect the root crowns over winter.
Due to its burning effects, using vinegar in the garden has been touted as a cure-all for a number of garden afflictions, most notably weed control. The acetic acid of vinegar dissolves the cell membranes resulting in desiccation of tissues and death of the plant.
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Daylilies are best cut back in autumn, once the leaves have had a full growing season on the plant. While there are some evergreen types of daylilies, most are herbaceous, meaning that the leaves die back in the wintertime and sprout anew in the early spring.
Many gardeners cut back their perennials much too soon. There are nuances specific to certain perennials that dictate whether it is better to cut them back in fall or spring, but the general rule I like to follow is to only cut back perennials that start looking bad in fall.
Many landscaping professionals actually practice — and prefer — fall mulching. Fall mulch works like spring mulch to retain soil moisture, suppress weed growth and protect bare soil from erosion.
Fall mulching saves time and energy in the spring because it cuts down on the need to weed. It also saves you the labor of spreading new soil and mulch after winter snows. You may also save money too. Mulched perennials are likely to last the winter, reducing your outlay on new blooms.
Fertilizing in the fall helps plants be hardier when the temperatures drop. We also recommend applying fertilizer in the late fall, toward the end of October or early November. This application will catalyze one last frenzy of root growth and really give your plants some staying power through the cold months.
By not cutting back the statuesque achilleas, eryngiums, perennial astilbes, sedums, alliums and many ornamental grasses, you can enjoy their structure against a winter sky. The sight of their stems silvered with frost adds a whole new level of interest to the garden.