Late Winter Tulip Forcing
Have you learned how to “bridge the gap”? The late winter and early spring bulb forcing period can be tricky to plan for. It takes some growers years to figure out how to build a bulb forcing program that transitions seamlessly from early winter into spring, and finally to their outdoor field crops.
Here are some of the hang ups we see and how to prevent them.
Trying to force bulbs that are too eager.
Tulip bulbs that are pre-cooled as soon as cooling is possible are prepared for early winter forcing successions for flowers from roughly Christmas to Valentine’s Day. Later varieties like double late tulips with pre-cooling generally perform better after the holiday.
“5C” prepared bulbs start to grow very eager in late February and beyond. It’s best to force bulbs that entered their cooling later for these later successions. This is why most of us use untreated bulbs for our fields in cold climates. Our natural winters provide the cooling the bulbs need.
For late winter successions, choose bulbs that began their cooling later. “Untreated” tulip bulbs that have been properly stored during the winter months can be great for planting late hydroponic or soil crate successions. Log in to see our (formerly) untreated tulip bulbs. They’re ready to go!
Growing too warm.
As the days grow longer and outside temperatures grow warmer, it’s important that growers pay attention to the temperatures in their grow spaces and work to keep them cool. Spring bulbs do not like to grow warm, and it’s good for us to remember that when we are forcing bulbs in crates, trays, and pots— our plants are more susceptible to warming temps than they are when planted in the cool ground. Generally speaking, you want to try and keep your grow spaced below 70F for spring bulbs.
Growing too humid.
As the season changes to spring, many growers see more snowmelt or rainfall. Both can lead to an increase in humidity levels that can be problematic for spring bulb forcing. Growers should avoid exposing their developing plants to levels above 79% relative humidity. Adding warmth to a grow space, plus ventilation (an open vent or door) can help express excess humidity quickly from a grow space.
Failing to water enough.
The finish line is nearly there! Don’t forget to keep watering your spring forced bulbs well. Spring flowers are thirsty. To avoid humidity spikes, water in the morning on sunny days so that the plants can take up the moisture more readily and humidity can burn off and be vented during the day time. Avoid nighttime or low light watering when the plants are less active and extra water will linger.
