The photo shows tulip trays stacked inside our coolers. After planting each tray with tulip bulbs, they are moved to our coolers which creates an artificial environment simulating Pacific Northwest winters – minus the rain.
The trays enter the cooler with the air chilled to approximately 45 degrees. That temperature is slowly dropped to a near freezing and then raised back again towards the temperature at entry. This cooling period lasts for 16 weeks or longer.
After the cooling period, trays are removed from the coolers and ready for entry into our greenhouses.
These tulip sprouts may not look all that familiar to home gardeners right now, because this part of the stem would typically be covered by soil.
Each tulip variety will look a bit different at this stage. Some stems will be more green, yellow, brown, or even reddish colored. Some will be shorter, some taller, and some even a little bit bent.
A few days in and now things are starting to look a little more familiar, with green sprouts showing up. Almost two weeks in and we have some serious tulip foliage.
Nearly three weeks after entering the greenhouse, tulip stems are ready for picking.
During the summer months, tulips will average about 17-20 days of growth due to the longer daylight hours and warmer temperatures.
As summer turns to fall, more days of growth are required and we then plan on almost 4 weeks of growth for the bulbs in our winter tulip sets.
For more photos showing the process, visit the RoozenGaarde Facebook page.