Christine’s Growers Notes
Poinsettias 2020
Week Number: 33
Environmental Conditions:
This week we potted 1800 poinsettias and placed them in zone 4. The shade curtain is extended to 85% allowing 15% ventilation. This is important to allow for air flow passively from the side walls and out the gutter vents. Outdoor temperatures have been high this week, into the late 20’s and early 30’s. Plant’s stop growing at 25 degrees. Bottom heat is turned on to 23C to encourage and stimulate root growth development. The same day and night temperature make for a stable environment to reduce plant stress and encourage root and vegetative growth. Worth noting, we aren’t focused on the vegetative growth at this point and want to keep the internode length consistent and short to result in compact and well branched final plants.
Day: Heating Setpoint 18C Cooling Setpoint 21C (adjusted from 23C because of hot day temperatures)
Night: Heating Setpoint 18C Cooling Setpoint 21C
Average Daily Temperature:
Supplemental Lighting: None required at this time.
Hours of Black Out: None required at this time.
Nutrient:
EC target is 1.5 – 2.0 pH target is 5.7 – 6.3
EC: N/A pH: N/A
Watering/Fertilizer:
After potting the poinsettias, we watered them in with clear water. The first watering is important to secure the plugs in the surrounding soil and ensure there is adequate water movement throughout the soil. Our second watering will be with a fertilizer with high Calcium Nitrate to encourage root development.
Observations:
This week the students potted up 1800 poinsettias and placed them pot to pot in zone 4 on August 11 and August 13. Plants received were in good health however, in ideal conditions they would be planted directly after receiving them. I do not anticipate this being a set back for the plants.
Outdoor day temperatures have been extremely high this week – later 20’s into the early 30’s. This excessive heat is stressful for the plants. To mitigate the high temperatures, I have been opening the side walls early in the morning and closing them late at night to bring down the average daily temperatures. We do not want the night temperature to dip below 18C and I am watching for this daily. I am concerned about the high temperatures and its possible stress effect on the plants. They need to be assessed and monitored throughout the day – every day.
In this stage of production, we are focusing our decisions to encourage root growth. We planted the poinsettia plugs into 4” and 6” pots, these will be their final pot sizes. The bottom heat is set for 23C and I have been wetting the floor at least two (2) times daily to help increase humidity. The increased humidity will reduce transplant stress. Place the plants pot to pot will create a microclimate and contribute towards higher humidity and reduced possibility of desiccation.
We watered the plants in with clear water and will water with a high Calcium Nitrate fertilizer in the next watering. We watered so that the excess water was dripping out of the bottom of the pot to ensure proper drainage. Due to the high temperatures we have been having I anticipate the plants requiring water frequently once they are rooted out in the pot.
Moving forward, I anticipate the plants being ready for pinch in week 35. To prepare for this I will continually assessing the plants to ensure they have enough nodes to pinch back for the final bract requirement of 6-7 bracts. I am concerned about root pest issues including fungus gnat larva and root rots in this stage of growth. This is because the roots aren’t fully developed and weak in the larger pot, which make them vulnerable to pest and disease pressure. To manage this concern I will ensure the plants aren’t stressed by providing them with watering at the correct time to avoid extreme dry/wet periods.
