Gardening Tips: Fall planting

I just returned from a trip to north/central Wisconsin where it seemed like the fall foliage color was a good deal ahead of ours here, but after only being away for four days, it looks pretty much the same here right now.

The weather here this past week has been close to perfect with cool nights and beautiful, sunny days. There are still some mosquitoes to deal with but they are sluggish and not reproducing like they were a month ago. Ground nesting yellow jackets and the black and white, bald faced hornets are still active however. Before you mow your lawn for the last, or perhaps next to last time, walk the area and look for hornet activity. If you discover hornets flying to and from a small hole in the sod, don’t mow since you will likely be attacked. Mark the entrance hole carefully and return after dark with a can of wasp and hornet spray and a flashlight. Spray half the can into the hole and the insects should be dead by the next morning. Bald faced hornet nests look like grey papier Mache footballs and they are as big now as they will get. If they are high in a tree it is best to just avoid them, but if they are under your deck or somewhere you walk, you may want to spray them at night as you would the ground nesting hornets.

For many of us, early fall is the nicest time of the year here in the Northern Catskill/Hudson valley region. The kids are back to school, the weather is beautiful with fewer mosquitoes, no black flies or no see ums and it is a great time to plant things!

Fall is almost as good, or in some cases, even a better time to plant trees, shrubs and perennials than spring. Shorter days and cooler temperatures place less demand on developing root systems and warm soil temperatures allow for rapid root growth. One of the main reason plants fail to become established in the home landscape is because of insufficient root development brought on by cold soil in the spring time, followed by dry conditions during the summer. That has not been the case this summer as the weather has been as close to perfect as I can remember. Many garden centers have sales on all sorts of plants and while they may not look quite as pretty as they would in the spring, they will look just as nice next spring if you plant them now.

Remember to dig a $50 hole for a $5 plant if you want it to become a permanent part of the landscape. Concentrate on making the hole much wider than you think it needs to be and not necessarily much deeper. Tree and shrub roots grow much more sideways than down. Very few trees and shrubs need holes more than 12 inches deep, but the excavated area can be 3 feet wide or even wider. For trees and shrubs I suggest that you add no fertilizer or any other soil amendments at time of planting unless you have extremely sandy soil. My philosophy is that the tree or shrub needs to adapt to your existing soil conditions and adding compost, peat moss and fertilizer to the back fill soil only serves to create artificial conditions for the roots to quickly fill in. Once the roots fill in the amended soil they have a very hard time expanding into the surrounding native soil, which sometimes causes them to die rather suddenly a year or so after planting.

For perennials, my advice is just the opposite! Take the time to dig down a foot deep if possible, remove large stones, add peat moss or compost up to one third by volume of the excavated soil and also mix in some organic fertilizer such as bone meal, composted manure and cottonseed meal or blood meal. Perennial root systems are not going to extend fifteen feet or more into the surrounding soil as tree or shrub roots will so it is important to create “cushy” rich soil right below for them to thrive.

All perennials, trees and shrubs will also grow much better if they have a three inch layer of organic mulch such as wood chips, shredded bark or pine nuggets over their root systems. Grasses and other plants seriously compete with the root systems of trees and shrubs and research indicates that trees may grow as much as four times faster if mulched, compared to allowing grass to grow right up the trunk.

Reach Bob Beyfuss at rlb14@cornell.edu.