Using Greenhouse Climate to Improve Shelf-life and Garden Performance

1. Using Greenhouse Climate toImprove Shelf-life and Garden Performance A Grower Toolbox from Jeffery’s Greenhouses

2. Grow Low and Slow VMI driven planning means: We only grow what we will ship No product in greenhouse grown on spec No benefit to tight crop schedules Allows us to grow cool with longer croptimes better quality better shelf-life better ability to modify timing of crop

3. Grow Low and Slow Empty greenhouses run cold until mid-February Heating with low pressure steam Allows very minimal heat input Heat pipes can be easily drained Winterizing < 2 hrs of labor per greenhouse Very minimal heating cost Lest pest/disease carryover

4. Grow Low and Slow

5. We heat with Steam Steam heat technology has evolved Very hot operating pipe temperature Compared to hot water heating systems Favourable ratio radiation vs convection Higher leaf vs air temperature Drier micro climate

6. Low Pressure Steam Heating Systems Higher Plant temperature vs Air temperature Plant temperature drives crop development Allows for lower ambient air temperature Energy savings through lower temp. target Steam Boilers are less efficient than Water Boilers But Steam Heat delivers energy efficiently to crops

7. Why should hot-water growers care? High pipe temperature heating = Better Crops My ideal hot water heating system At least 3 separately controlled top pipe system High pipe temperature with proper system lagging …even at modest heat demand Same energy, but more radiation, less convection Better microclimate in canopy

8. Keep plants active - Microclimate VPD + Root Pressure The nutrient and water transport pump of plants

9. Keep plants active - Microclimate VPD deficiency primarily a shelf-life issue soft tissue does not hold up in stores Maintain minimum of 4 mbar VPD at all times Active de-humidification costs money Shrink in greenhouse or stores costs A LOT more The most expensive form of energy is that which does not produce a crop that you can sell

11. Keep plants active - Microclimate Cardinal Sin: Too much Energy Curtain We do not merely heat to maintain temperature We heat to supply energy to the plants (in form of VPD) Some energy loss in greenhouse is desirable Air is cooling along roof Cooling condenses moisture onto roof Condensation removes water vapor from air Increases VPD

12. Keep plants active - Microclimate Closing energy curtains too early: Locks in heat, but also Prevents water vapor from condensing on roof Humidity approaches saturation Water/Nutrient transport in plant stalls Primarily an issue in spring/fall when energy input is minimal

13. Keep plants active - Microclimate We do not close energy curtains Unless outdoor cold enough so that Heating system remains active with Heat input under curtain of > 5% capacity

14. Keep plants active - Microclimate Vertical Air Flow and Crop Canopy Microclimate

15. Keep plants active - Microclimate Top heat with vertical air-flow fans Improves distribution of warm air into crop If warm air is forced into canopy Air temperature relatively warmer than foliage Climate computer measures ambient air temperature Climate experienced by plants cannot be determined by climate computer measurements alone

16. Heated Greenhouse – No vertical fans Creates SLOW vertical air circulation

17. Heated Greenhouse – with vertical fans Warm air is FORCED into the plant canopy

18. WITHOUT vertical fans: • Radiation heats foliage directly • Warm air not forced into canopy • Leaf temperature INCREASES compared to ambient air • Canopy VPD increases compared to ambient measurements • Microclimate drier • Plants WARMER and MORE ACTIVE

19. WITH vertical fans: • Less direct radiation onto foliage • Warm air is forced into canopy • Leaf temperature DECREASES compared to ambient air • Canopy VPD decreases compared to ambient measurements • More moisture in microclimate • Plants COOLER and LESS ACTIVE

20. Keep plants active - Microclimate Important Computer measures AMBIENT VPD Not the VPD experienced by plant Ratio Ambient vs Microclimate depends on Ratio of convective vs radiation energy into canopy Grower awareness is critical Climate targets must compensate

21. Keep plants active - Microclimate Top-heat with vertical HAF More moisture in microclimate than without fans With otherwise identical ambient climate For improved plant quality and shelf-life We turn OFF fans first half of night Costs some energy, but Plants are more active and finish healthier

22. Keep plants active - Microclimate Energy Inputwhile HAF off Ambient VPD

23. What about bottom heat ? Bottom heat does not heat foliage directly Ambient (measured) air always warmer/drier than microclimate around foliage Feet-in-the-fireplace & Head-in-the-freezer Average plant temperature is OK, but roots are active, when foliage is not

24. Think “Plant Perspective” • Unless we continuously deliver energy to the plant and/or increase VPD, our crops will “stall”

25. Day Night Differential and Daily Light Integral Night temperature influences how assimilates from preceding day are distributed in the plant During dark days (less than 8-10 mol/m² light) most plants are not able to assimilate enough to support the effect of higher night temperatures No benefit from higher heating costs Higher temperatures may create net carb loss

26. With low light integrals during preceding day, we apply less temperature increase at night Prevents carbohydrate depletion Saves on energy costs With higher light integrals during preceding day, we apply more temperature increase at night Reduces carbohydrate sinking Prevents stretch Increases C/N ratio in canopy Day Night Differential and Daily Light Integral

27. Low Light Integral = Lower Night Temperature Light Integral

28. High Light Integral = Higher Night Temperature Light Integral

29. Most expensive crops are those that don’t sell No such thing as cheap quality Shelf-life comes with cost Worthwhile investment Quality Crops demand Quality Input

30. Thank You Albert Grimm Jeffery’s Greenhouses Inc.1036 Lakeshore Road WestSt. Catharines, OntarioL2R 6P9Canada http://www.jefferysgreenhouses.com Tel: 905 934 0514 E-mail: AlbertG@jefferysgreenhouses.com