How to put the ground to bed

UNH Cooperative Extension
Tuesday, October 03, 2017

Heading into October, the weather forecast predicts cooler temperatures to come. Gardens are slowing down rapidly, reminding us that now is the time to take action to ensure a successful season next year.

Protect sensitive plants from frost

As night-time temperatures begin to drop, the first order of business should be harvesting heat-loving vegetables and ornamentals that won’t tolerate frost. Tomatoes and peppers are obvious examples, but even potatoes and winter squash don’t stand to gain anything by remaining in the garden once the tops begin to die down.

Other plants needing immediate attention are geraniums, begonias, fuchsias and many of our summer bulbs including dahlia, canna and elephant ear.

Tidy up beds

Clean up annual beds, but take advantage of fall leaves for additions of organic matter. Shred the leaves with a lawn mower and apply as a top-dressed mulch. Compost and manures can be added in the fall as well. Incorporate into the top few inches of soil for best results. Avoid leaving bare soil at all costs.

Perennial beds should also be tidied up, but don’t overdo it. Remove diseased top growth, but consider leaving seed heads that may provide winter interest and food for wildlife. Healthy top growth can often be returned to the soil as mulch or composted for next season.

Tree and shrub care

Remember that some trees and shrubs require winter protection as well. Thin-barked trees such as ornamental cherries often suffer from winter damage, often described as “southwest injury.” This is because the winter sun reflects off of the snow during the winter months on the southwest side of the tree. As the light hits the dark bark of the tree, it thaws during the day and refreezes as temperatures drop at night. Over time this freezing and thawing can result in bark damage resulting in more serious permanent damage. To avoid this issue, consider wrapping sensitive trees with plastic or paper tree guards. These are often white in color to avoid heating up during the day. Burlap screening could also be used with the same protective effect. Remove these protective materials once the snow melts in spring.

Shrubs planted under house eaves often take a beating when snow and ice come crashing down on them. Protect them with homemade wooden framing or store bought pop-up protection made from steel rods and synthetic fabric.

Prune appropriately

Most pruning of trees and shrubs should be delayed until the plants are completely dormant. Pruning before dormancy can result in poor wound healing or unwanted growth that may not tolerate winter temperatures. To be sure plants are in full dormancy, gardeners often wait until mid-February to tackle pruning woody ornamentals. Remember, plants that bloom before mid-June should likely be pruned just after flowering is completed, so consider bloom times to avoid snipping off potential flower buds.

Mulch should be applied once the ground has cooled down and plants have gone dormant. The goal is to use the mulch as insulation, however, in this case it should keep the plants cold throughout the dormant season. This application of 3 to 4 inches of mulch will prevent fluctuating temperatures from causing the plants to lose hardiness, only to be bitten back should a sudden cold snap return.

Test your soil

If you haven’t submitted a soil sample from your garden, make this the year you get it done. Knowing which nutrients are plentiful or scarce in your soil may be the very most important factor in growing a successful garden. Within three weeks you will have your results. Collect your samples before the ground freezes and be ready to follow the recommendations come spring. Instructions and forms can be found at extension.unh.edu.

(Jeremy DeLisle is the program coordinator for the UNH Cooperative Extension Education Center. The center answers questions about gardening and more at answers@unh.edu.)