Winterizing at NTC
Winter is typically the slow period for most growers, a good time to find warmer weather, catch up on projects put off during the growing season, and most importantly, get some crucial rest and relaxation. While NTC’s horticulturists have certainly been making good use of the down time, there is still plenty going on in the background as the winter winds howl.
The winter starts with winterizing all our nursery plants. Every plant is allowed to go dormant and is subject to multiple frosts. All deciduous trees are allowed to abscise their foliage before being put into “Winter Storage”. The smaller, newly propagated plants get the most favorable winter resting spot – the University of Rhode Island’s walk-in cooler, which is part of the campus greenhouse facility. The consistent cool temperatures and darkness is ideal for the plants to remain dormant, without having their containerized root system subject to freezing and thawing. Plants in the cooler are checked on every 2 weeks for water, with moisture levels being maintained at damp.
All other containers are stacked together, laid down, and covered with 2 layers of fabric and plastic, at our little nursery at Rogers High School. This cover will insulate the plants and provide a good buffer from wind, ice, and snow. Freezing and thawing is more limited under the cover, and the complete darkness will keep the plants dormant longer even when the temperature begins to rise as the days lengthen in the spring. The process of covering takes about 2 hours, and its best done with 3 people. This year, we got our Executive Director Natasha to help us out!
Winter is also a good time to propagate hardwood cuttings of select evergreens. This winter, we are attempting to root 3 different types of holly (ilex), Japanese Pieris, Weeping Alaskan Cedar, and False Holly (osmanthus heterophyllus). Again, we are thankful to URI for allowing us access to their facilities. All the cuttings have been treated with IBA Talc rooting powder, inserted into a suitable rooting media, and placed under a seal polyethylene tent with intermittent mist and bottom heat. We are hopeful to have some rooting later in the winter!
With select rooted cuttings, its best to keep them growing through the dormant season in order to have a decent sized plant come spring. In the early fall, we rooted 4 different evergreen azalea cultivars in a sealed polyethylene tent. These cuttings were potted up in late November and moved to our heated greenhouse. Over the last couple of weeks, the azaleas have started to flush out with bright green growth. It is things like this that get you through to the spring.
At NTC, we are big believers in tree propagation by seed. The sowing of seeds will start in late winter and early spring, but right now, all our seeds are being given the treatment they need for best germination. Many seeds have been stratified in Ziplock plastic bags filled with moist media and are stored in the fridge. Others have been placed in little seed trays, which are kept in the cooler with our overwintering trees. This cold period aids with embryo development and will hasten germination when we are ready to sow. Seeds that do not need a cold period maintain viability better if kept at cooler temperatures, so they are stored in the fridge in sealed containers.
Winter isn’t complete until you escape it temporarily, and NTC’s Hort staff took some time to get out of Rhode Island and relax under palm trees and enjoy cool ocean breezes.
Joe Verstandig — Living Collections Manager
