sir rance alot
Active Member
In addition to light quality i.e. MH/HPS, you can control plant height by manipulating flower chamber air temperature. Stem elongation is strongly influenced by the difference (DIF) between the day air temperature (DT) and night air temperature (NT). This is represented as: DIF = DT – NT. For instance when the DT is higher than the NT, DIF is positive. If the DT and NT are the same, DIF is zero. If the NT is warmer than the DT, DIF is negative.
As DIF is more positive (a larger difference between DT and NT), stem elongation increases (Figure 4). As DIF decreases toward zero or becomes negative, stem elongation is suppressed. Running a higher NT than DT can be a very effective means of suppressing elongation. Increased heating at night to achieve a negative DIF can also be expensive.
There is an alternative, yet effective, strategy using the difference between DT and NT. This method is called DIP, DROP or Cold Shock. You can DROP or DIP your air temperature by running a constant DT and NT for most of the day. Then, about 30 to 60 minutes before sunrise, DROP your air temperature by 5 to 10°F for up to four hours. This will create a negative DIF without drastically increasing your nighttime heating and allow you to take advantage of the naturally warmer afternoons. Because the majority of stem elongation occurs during the morning, dropping your air temperature early can be very effective in reducing elongation.
Thanks to GreenHouse Grower and others for the info.
As DIF is more positive (a larger difference between DT and NT), stem elongation increases (Figure 4). As DIF decreases toward zero or becomes negative, stem elongation is suppressed. Running a higher NT than DT can be a very effective means of suppressing elongation. Increased heating at night to achieve a negative DIF can also be expensive.
There is an alternative, yet effective, strategy using the difference between DT and NT. This method is called DIP, DROP or Cold Shock. You can DROP or DIP your air temperature by running a constant DT and NT for most of the day. Then, about 30 to 60 minutes before sunrise, DROP your air temperature by 5 to 10°F for up to four hours. This will create a negative DIF without drastically increasing your nighttime heating and allow you to take advantage of the naturally warmer afternoons. Because the majority of stem elongation occurs during the morning, dropping your air temperature early can be very effective in reducing elongation.
Thanks to GreenHouse Grower and others for the info.
