Questions with Josiah Raymer
Andropogon 'Dancing Wind'
Emerald Coast Growers

Questions with Josiah Raymer

Advertorial - Ask the Experts: Perennials

Take the mystery out of overwintering perennials for spring sales.

October 2, 2019

Perennials are a profitable crop. And to keep those sales up, Josiah Raymer, general manager at Emerald Coast Growers, advises how make a few production adjustments to keep your perennial crops looking their best.

1 | When should I pot perennial liners to overwinter for next year?

Early fall is a great time to pot liners to start bulking up for spring sales. This works well for perennial plants such as Phlox and Astilbe and ornamental grasses such as Pennisetum and Miscanthus.

If you’re wanting early spring sales of warm-weather grasses, you’ll need to perform some well-timed bulking. Grasses such as Miscanthus, Panicum, Andropogon and Schizachyrium will respond well to bulking in summer and fall months. Put up liners in early to mid-summer, allowing enough time to finish by fall. June to July is a good window. Then, let them get a good dormancy period over the winter, which promotes good vigor coming out of dormancy.

2 | Do I plant different perennials at different times?

Be careful not to pot up day-length sensitive plants too late. The shortening days and cooler temperatures trigger dormancy. Remember, tender perennials don’t bulk and overwinter well.

One way to control crops with a strong photoperiod response is by getting them potted early enough in the summer that they will be finished by September or early October. Crops with a weaker photoperiod response, such as perennial grasses Pennisetum and Miscanthus, can be potted later in summer, as they will continue to grow for an additional four to eight weeks depending on day length and temperature.

If you have potting schedules or other constraints that force you to do all of your potting at once, changing your liner size can also help control finish times. Starting with a larger liner can shorten finish times and get your crops finished on time.

3 | Should I overwinter my plants in cold frames or outside?

Either will work. Use a perennial cloth to provide protection from frigid winter in northern climates. Farther south you may be able to get away with placing plants pot tight for protection. If you’re using cold frames, be sure to vent on warmer days, or plants may overheat.

4 | How do I adjust my fertility program for overwintering?

You want to cut back as you’re nearing the dormancy period. The most flexible option is liquid feeding, but you can also schedule a slow-release fertilizer that will run out as fall begins. Choose a fertilizer with lower nitrogen as you’re moving toward dormancy — remember you want to encourage a shift from lush new growth to energy storage in the roots.

As you near the end of overwintering, and before your crops come out of dormancy, it’s important to get pH and electrical conductivity (EC) readings. You may need an application of liquid feed fertilizer, or you may need to leach your pots if your EC is low or high respectively.

5 | How do I prepare my leftover pots for overwintering?

Start by removing old foliage just before winter, but after plants go dormant. The less organic matter to deal with in spring, the better, and you won’t have to work through new growth to cut back old foliage. Both perennials and ornamental grasses can overwinter next to new production.

If plants aren’t root bound, fertilize them when they break dormancy in the spring to have them ready for early sales. If they are root bound, shift material into a larger size in the fall or the spring. Base your decision to shift them in the fall or wait until spring on whether they have enough time to root out in their new pots prior to dormancy.

A preventive fungicide drench can help reduce root rot issues in areas with wet winters.

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