• Temperatures are more moderate, meaning less moisture loss through leaves, less plant stress, and less need for watering.
• Weeds provide less competition for new plantings. Annual weeds that are removed now, before they go to seed, won’t be back. Perennial weeds can be killed off better with Roundup™ in the fall than in the spring.
• Winds aren’t as much of a problem in the fall as they are in the spring, resulting in less dehydration, less staking problems, less leaf burn.
• Harmful insect populations are much reduced from spring and summer levels.
• The soil is still warm enough to stimulate root growth. The warmth stored in the earth all summer remains well into fall, but without the stress of blazing summer sun. Plants get to enjoy two seasons of moderate temperatures within which to establish roots before having to face the stress of summer again. Root growth continues as long as soil temperatures in the top 6-12″ of soil are above 38˙ and adequate moisture is available. Applying a thick (2-3”) mulch in early fall will keep the soil warm for even longer. Be sure to leave a 2-inch gap between the mulch and the tree trunk. If it’s too close, mice can burrow under the mulch and chew a ring around your tree’s trunk, thereby killing the tree.
• Root growth is greatest in the fall. Plants prioritize: in spring and early summer flowers, fruits and leaves get the most energy; in mid-to-late summer, fruiting, blooming and ripening peak, leaf growth lessens and stems begin to get more energy.
As fall approaches, plant tops go dormant and next year’s buds finish forming, resulting in a decrease in the energy required by the above-ground parts of your plants. This lets plants use that energy for a tremendous increase in root growth. In fact, in fall, as stem growth tapers off, 70-80% of the season’s new root growth occurs. This means that plants established in the fall have better root systems to support the following spring’s rush of new top growth than spring plantings.
• There are lots of active beneficial microbes in soils this time of year! This means that organic soil amendments added now to planting beds will be readily broken down and made available to burgeoning plant roots.
• The weather is nicer. It’s more fun to work in the yard this time of year! And the more prep and cleanup work you do now, the more time you’ll have in the spring for the more creative aspects of gardening.