Bonsai Fall and Winter Care

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1 Bonsai Fall and Winter Care Tree Physiology and Greenhouse Protection Steve Ulrich Ottawa Bonsai Society January Monthly Meeting, 15 January 2018

classes on bonsai fundamentals with Éric Auger Taking classes on styling process with

2 Horticultural Biography Introduced to bonsais in 1999 First yamadoris in 2000 and 2001 First greenhouse in 2009 Second greenhouse in 2013 Third greenhouse in 2017 Currently Taking classes on bonsai fundamentals with Éric Auger Taking classes on styling process with Michele Andolfo Tier 2 Bonsai Miraimember Part-time certificate in horticulture at l Université Laval 2

3 Tonight s Program What happens with our trees in the fall? Physiology Protection What happens with our trees in the winter? Physiology Protection 3

4 Fall From late September to late December Major characteristics Daylight length decreases Temperature decreases Trigger end of vascular tissue growth Signs Less utilization of water Fertilizer not decomposed (if using pelletized form) 4

5 Fall - Tree Physiology but PHOTOSYNTHESIS CONTINUES! 6 H 2 O + 6 CO 2 + sunlight C 6 H 12 O O 2 5

6 Fall - Tree Physiology Energy (C 6 H 12 O 6 )not used for growth anymore COLD ACCLIMATATION PERIOD (PROTECTION FROM COLD DAMAGE) (PREVENT LIVING CELLS FROM FREEZING) (A LIVING CELL THAT FREEZES IS A DEAD CELL) (AND THIS IS A BAD THING) 6

7 Fall - Tree Physiology Cold Acclimatation Strategies Antifreeze C 6 H 12 O 6 pumped inside the cells Extracellular Freeze H 2 O moves out of the cells Lowers freezing point of H 2 O in the cells H 2 Obetween the cells freezes Takes time! White Spruce Thuya Eastern White Pine Larch Supercooling H 2 O inside the cells remains liquid below freezing point 7

8 Fall - Tree Physiology DO NOT HEAVILY PRUNE OR STYLE IN LATE SUMMER/FALL 8

9 Fall - Tree Physiology Cold acclimatation strategies are efficient up to a point! This point is known as cold hardiness lowest temperature below the freezing point to which a tree can be subjected without being damaged Throughout the fall, cold hardiness increases 9

10 Fall - Tree Physiology Cold Hardiness of Eastern White Pine Bonsai Winter Care - Steve Ulrich 10

11 Fall - Tree Physiology Cold Hardiness of Eastern Larch 11

12 Fall - Tree Physiology In the fall, through continued photosynthesis, energy is used for cold acclimatation using various strategies Cold hardiness increases Growth stops 12

13 Fall - Protection Portion of our trees most susceptible to cold damage ROOTS ARE HIGHLY SUSCEPTIBLE TO COLD DAMAGE 13

14 Fall - Protection Early Fall First Frosts Need to act when -2 degc for a short period of time Which trees need to be protected? Small pots (shohin, medium-sized trees) Recently pruned or lack foliage mass Unhealthy trees Type of tree (i.e., zones) Strategy Put them on the ground 14

15 Fall - Protection Fall Need to act when -2 degc for a few hours Which trees need to be protected? In theory: same as before In practice: all Strategy Mulch Dark shelter Cold greenhouse 15

16 Tonight s Program What happens with our trees in the fall? Physiology Protection What happens with our trees in the winter? Physiology Protection 16

17 Winter - Tree Physiology Cold hardiness decreases Buds do not grow Endodormancy(True Dormancy) Triggered by environmental conditions in the fall Internal physiological processes prevent growth Remain in this state until sufficient chilling units are accumulated 17

18 Winter - Tree Physiology Chilling Units T < 1.4 C = 0 chill units 1.4 < T < 2.4 C = 0.5 chill units/hour 2.4 < T < 9.1 C = 1 chill unit/hour 9.1< T < 12.4 C = 0.5 chill units/hour 12.4 < T < 15.9 C = 0 chill units 15.9 < T < 18.0 C = -0.5 chill units/hour T > 18.0 C = -1 chill units/hour Example: Malus requires 1000 to 1200 of chilling units 18

19 Winter - Tree Physiology Once chilling units are satisfied, trees break their endodormancy, and buds can start to elongate but they don t why? Ecodormancy(Apparent Dormancy) External conditions unfavorable to growth Growth will resume once environmental conditions are favorable 19

20 Winter - Protection Strategy Mulch Dark shelter Cold greenhouse Shelter vs. Cold Greenhouse Shelter are passive Greenhouse actively controls the environmental conditions 20

21 Winter - Protection Benefits of a Cold Greenhouse Ensure proper protection from cold damage to weaker, small-potted trees Protect from cold wind Opportunity to have semi-hardy trees in your collection (Japanese maples) Protect against snow loads Protect from animal-made damage Protect cheap pots from cracking Control level of moisture delivered to the trees Evergreen coniferous trees continue photosynthesising through the winter Stops at -3/-5 C and +35 C Optimal between +10/+25 C 4 C metabolic activities give the potential for root growth Extend the growing season (early repot) Greater opportunity to pursue bonsai in the fall/winter 21

22 Winter - Protection Key Aspects of Cold Greenhouse Size: the larger, the better 13 x 13 x 11 22

23 Winter - Protection Key Aspects of Cold Greenhouse Insulation Air-inflated double layer of polyethylene (6 mil) 23

24 Winter - Protection Key Aspects of Cold Greenhouse Heating: in Ottawa/Gatineau area this is necessary! 6,000 W Heater (20,472 BTU) 24

25 Winter - Protection Key Aspects of Cold Greenhouse Heating: in Ottawa/Gatineau area this is necessary! 6,000 W Heater (20,472 BTU) 25

26 Winter - Protection Key Aspects of Cold Greenhouse Ventilation: keep it cool! 12 exhaust fan = 1640CFM 26

27 Winter - Protection Key Aspects of Cold Greenhouse Electricity (as per local code) Expensive, but necessary 27

28 References Glerum, C., Frost Hardiness and Dormancy in Conifers, Northeastern Area Nurserymen s Conference, Nova Scotia, Bigras, F. J., Colombo, S. J. (Eds.), Conifer Cold Hardiness, Springer Science, Dawson, T., Photosynthetic Adaptation to Temperature, Integrative Biology (Course IB151), University of California, Berkeley. Ortho, All About Greenhouses, Wiley, Hagedorn, M., The Difference Between Plant Hardiness and Chilling, Crataegus Bonsai, Neil, R., Winter Preparation, Bonsai Mirai, Green, A., Dormancy and Chill Units, Ontario Ministry of Agriculture, Food and Rural Affairs, Tweddell, R. J., L endurcissement au froid des plantes, Organisation et physiologie des plantes(course BIO-1904), Université Laval,

29 Questions? Bonsai Fall and Winter Care - Steve Ulrich 29

Junipers as bonsai. V.3.2 April, Vianney Leduc

Junipers as bonsai. V.3.2 April, Vianney Leduc Junipers as bonsai V.3.2 April, 2017 Vianney Leduc 1- Introduction a. Esthetic quality The main beauty of junipers lies in the contrast between the living part and the deadwood California juniper Picture