Decreasing Winter Plant Loss

By Ron Arpin, Little Valley Wholesale Nursery

With our increasing erratic weather, wildlife damage and staying on top of cultural practices, it is more difficult than ever to prepare and protect our nursery stock from winter loss. Following are strategies that will help decrease winter losses.

  • Order poly or winter cover fabric in May or June to take advantage of early order discounts and to order custom sizes.
  • Have supplemental supplies on hand in September such as staples, tac strip, strapping and min/max thermometers.
  • Monitor nightly low temperatures in October. A gradual drop into low twenties is ideal, but unfortunately gradual drops are not a regular occurrence.
  • Beware of warm fall temperatures into late October and early November. It becomes more likely that when the first storms arrive, there will be lows in the single digits to below zero.
  • To avoid severe temperature drops make it a goal to complete winter protection by Nov. 1.
  • Once covered, monitoring potting media moisture is critical. Take advantage of warmer days before stormy periods to check media moisture and water any dry media. Regardless of plant hardiness, plant material in dry media will die.
  • Monitor media moisture consistently until material is uncovered in April or May. It is not unusual to experience multiple freeze thaw cycles. If warm temperatures are forecast for a week or more, check soil media for thaw. Water if necessary.
  • Don’t water frozen soil media. Frozen media will not drain and the standing water will kill plant material.
  • Nutrient deficient plant material will experience higher winter mortality. Provide supplemental feeding in August and September to give plant material a boost and improve winter survival.
  • After material is stored for the winter, apply and monitor rodent bait stations. Voles can cause considerable damage to plant crowns of desired material and grasses.
  • If available, consider overwintering marginally winter hardy material in greenhouse structures with supplemental heat. A 35-degree Fahrenheit minimum air temperature is sufficient to protect sensitive plants.
  • If heated space is not available consider minimizing late season inventories of marginally winter hardy material. Marginally hardy nursery material includes: Agastache, Ajuga, Clematis, Coneflower varieties, Delphinium varieties, Ferns, Miscanthus grass varieties, Lavender, Painted Daisy varieties, Plumbago, Sweet Woodruff, Azalea, Bamboo, Beauty Bush, Butterfly Bush, Firethorn, Hydrangea, Quince, Rhododendron, and Weigela.
  • Consider minimizing late season inventories of conifers and evergreens that tend to experience winter foliage burn.
  • Buck deer will damage field trees and are difficult to keep out during the fall season. An eight-foot barbed wire or electric deer fence is an option.
  • Options for rabbit control include: rabbit repellent, surrounding susceptible material with two- to three-foot-tall chicken wire, and hiring a wildlife control company. Check with the Colorado Division of Wildlife for pertinent regulations and permits. Rabbits prefer to feed on Burning Bush, Crabapples, grasses, Spirea and anything else they take a fancy to.

If you plan and prepare for the worst by maintaining cultural practices, monitoring the weather, taking advantage of the weather breaks, and taking steps to minimize wildlife damage, you can trust that the fall plant inventory you overwinter will provide an excellent crop for your spring season with minimal loss.