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Between Seasons

Paul Pilon
I hope you’ve been able to enjoy the wonderful fall season we had. When I’m not at work, I’ve been spending as much time as I can working on a few landscaping projects and planting new perennial beds around the house. Back at work, I worked on getting existing crops ready for winter, made programs and planning for next year, and worked on trials to improve future crops.

Below, I share several of the areas I work on each fall during this transitional time of the year to prepare for overwintering and next year’s production.

Irrigation and fertility: As fall approaches and the weather patterns change, it’s very important to adjust the amount of water and fertilizer being applied. In the fall, plants aren’t growing as fast and don’t use as much water and fertilizer as they do during the warmer summer conditions. Providing too much of these things can lead to soft growth, delay acclimation to cooler temperatures and contribute to the development of diseases. Provide only enough irrigation and fertilizer to match the plant’s needs. A good rule thumb is to reduce each of these by around 50%.

Root health: When overwintering perennials, the main goal for successful overwintering is to ensure the root system survives the cold winter months. In order to do that, it’s important to go into winter having a healthy root system. Besides proper irrigation and fertilizer management, growers need to evaluate the root health of their perennials in the early fall. Early fall for me is early September. If root health is questionable or compromised, I apply a broad-spectrum fungicide. If all goes well, root health will improve or recover during the weeks ahead and be healthy enough to survive the cold winter months.

Pest and diseases: Let’s face it—we grow plants and no matter how well we think we have things under control, cultural issues such as insects or diseases can be present in the fall. I’ve seen it more times than I care to admit, and it’s not uncommon to see low levels of pests, such as aphids or whiteflies, or diseases such as Botrytis and powdery mildew, present on the plants in the autumn. You can tell yourself these problems will be removed when trimming the plants back or the cold temperatures will take care of these issues. Sure, these factors may somewhat reduce these issues, but, unfortunately, when these problems are present in the fall, they almost always reoccur in the spring. Over the years, I’ve found it very beneficial to manage insects and diseases in the fall. As they say, “An ounce of prevention is worth a pound of cure.”

Temperatures: I prefer to schedule my summer and fall plantings so the perennials are well-rooted before cold sets in. Of course, the weather varies from year to year, but in Michigan, I can usually count on suitable temperatures for rooting and bulking to last until mid-October in most years. I’m not a fan of planting later in the fall and having to provide heat to complete root development before the plants can be overwintered. I prefer to let Mother Nature provide the heat at her expense, not mine. Assuming the plants are well-rooted, I also like to keep them as close to the outside temperature as possible. Yes, frost is acceptable and encouraged to help plants get acclimated on their journey towards dormancy.

Trimming: I’ve been asked numerous times over the years about when the best time is to trim plants and remove the old foliage. For most plants, I prefer to wait as long as possible. If I’m moving the plants in the fall (discussed below), then I generally opt to trim them at that time rather than coming back and trimming them at a later time. Since most perennials are deciduous, the plants can be trimmed and the old foliage removed anytime during the dormancy period. This is often a good activity to keep labor busy during the winter months before spring planting begins.

Article ImagePictured: Fall is a great time to clean production houses to remove old growing mix, plant debris and weeds. Proper cleaning isn’t just about washing houses, but entails using cleaners and disinfectants to bring the house up to a pest- and problem-free facility before crops are planted back into these spaces.

Fall cleaning: I don’t know about you, but I find it nearly impossible to actually plant perennials directly into their overwintering locations at the time they’re planted. These preferred locations are often already occupied by other perennials due to summer and fall sales. I use the fall as an opportunity to move the plants to the proper growing environments they’ll need in the spring. Needless to say, there’s often a lot of labor involved. When possible, I try to take advantage of the fall moves to thoroughly clean the production sites. This involves sweeping, power washing, cleaning with Strip-It Pro and disinfecting with KleenGrow before any crops are set down on them prior to overwintering. The empty houses are also cleaned and prepped so they’ll be ready for planting the spring crops in the late winter.

Early order programs: I’m sure many of you are aware of and actively participate in early order programs (EOP) many companies offer in the fall. These programs vary from company to company, but they often include discounted pricing, rebates and extended terms. You may not be aware of this, but many companies raise their prices after these programs are over or at the beginning of the year; this alone is a great reason to participate in EOP programs. I use the fall as an opportunity to review the successes and failures of the past pest and disease management programs over the past year, and design programs to optimize pest management next year. Taking advantage of EOP programs just makes sense (as well as saves many cents).

Even though the fall may seem like a calm time of the year, there’s much to do to prepare for the upcoming growing season. The pace may be different from the hustle and bustle of the spring, but I encourage you to not become complacent and take advantage of all of the things that could be done between seasons. GT

Paul Pilon is editor-at-large of the Perennial Pulse e-newsletter and Director of Growing at Opel Growers in Hudsonville, Michigan. He can be reached at

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