Cultural Practices

Pinching Plants

Plants that are slightly overgrown or need some shaping may benefit from being manually pinched. Pinching is often used to increase branching, shape plants and reduce plant height.  Pinching removes the apical dominance of the shoot which prevents branching.  Apical dominance results from the production of auxin, a natural plant hormone by the terminal growing point and young leaves. Removing the terminal growing point and young leaves (pinching), removes the source of auxin and allows dormant buds below the pinch to grow.

Watering Plants

Over-watered Plants: Stunted plants may be a sign of over-watering. Plants can be easily over-watered during overcast, cloudy weather, when plants with different water needs are grouped together or by an inexperienced waterer. Over-watering deprives roots of oxygen and increases susceptibility to root diseases such as Pythium and also leads to algae growth and infestations of fungus gnats and shore flies. Check roots regularly for signs of over-watering by gently removing plants from their containers.

Scouting Guidelines in Greenhouses

Small greenhouses (< 4,000 sq.) can be scouted as one unit. Larger greenhouses should be divided into 2,000 to 3,000 sq. ft. sections for ease of scouting. Scout propagation areas at least every 3 to 4 days. Use your prior experience to determine how many plants and which plants to inspect (those that are most susceptible to pests or diseases in your greenhouse). The more plants or locations inspected, the more likely it is that a problem will be detected in a timely manner, when treatments are the easiest.

Photoperiod Lighting to Create Long Days

Photoperiodic lighting is used to create long days for flower induction of long-day (LD) plants or to delay the flowering of short-day plants. Generally, long-day plants will flower when the daylength is longer than 14-16 hours (night length of less than 10 hours). Therefore, long-day lighting should be used from around Sept. 1 to April 15. Note that the critical daylength is likely to be different for each species.

September Greenhouse Clean-up and Biocontrol

It is best to clean greenhouses now rather than to waiting until just before you start your spring production.  This helps eliminate over-wintering sites for pests, in unheated greenhouses, especially if the winter is unseasonably warm. Remove all leftover plants, weeds and debris and clean the floor of spilled soil, and organic matter. Check areas around furnaces and alongside-walls and remove those small weeds that are often overlooked.  Repair tears in worn weed barriers.

Light for Propagation

Frigid temperatures may have some growers wanting to pulling energy curtains. However, if you are beginning to propagate young plants in the next few weeks, you will want to maximize the amount of light available to plants and increase daily light integral (DLI; cumulative measure of light intensity during a 24-hour period), if possible. For future, keep these low light months in mind. Try to keep your glazing material clean (and free of snow), change your old plastic, and if you have it, utilize high-intensity supplemental lighting.

Easter Lilies

The Easter holiday falls on April 5th in 2015. Easter Sunday always falls on date ranging from March 22nd at the earliest to April 25th at the latest. Holidays from April 3rd to April 15th are considered mid-date for the purpose greenhouse forcing.


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