How to overwinter decidous and pine young prebonsai seedlings in z5

2 months ago

I'm surprised there are very few persons that contribute on this forum anymore - everyone given up on bonsai? I thought I would ask for suggestions overwintering maple and pine young bonsai and prebonsai seedlings. We could have a mild winter like this past one where the lowest temp was 14F. Or we could go full scale multiple polar vortexs with -30 or even -40F and that's not including the windchill. Everything I've read on maples and pines says they have to be kept outdoors so they have a dormancy period but surely they don't mean in the above temps. I have a small greenhouse but it's only good for about 5 degrees in above 0 temps, then its the same as the outdoors. But it gets way too hot in the daytime with sun. I have an unheated basement but I would need growlights right? even if they are dormant?

Comments (3)

  • Timothy Wood
    2 months ago
    last modified: 2 months ago

    I do the same. I would sink the pots in the ground and throw leaves over them for protection. Just make sure they get water once a every two weeks or once a month. Yes they do need to experience the cold to go dormant but your wanting to do is protect the roots from the cold.

    I usually just leave mine on my patio under a awning and when it starts to drop down to the lower teens or single digits I just move them to my basement. The maples don’t need light when dormant since they don’t have leaves.

    lkayetwvz5 thanked Timothy Wood
  • lkayetwvz5
    Original Author
    2 months ago

    Thanks! Any and all experience is appreciated. I have never wintered over any Japanese maples before.

  • tropicofcancer (6b SW-PA)
    2 months ago

    Dormancy starts setting in below 45F but above 32F. This when all the biological changes are happening to prepare for winter. Plants have to spent certain number of hours between these two temperatures to get them fully ready. Usuallit is about 1000 hrs. After that the plant is just sleeping. Maple roots are good to about 20F so they need a lot of protection. Conifers can go below but still should be protected well. Unheated garage works well but may need more insulation if it gets way too cold for extended period.

    I have an unheated "greenhouse" sort of. Made with EMT tubes and covered in white plastic that cuts down the light by 70%. The white plastic reduces the temperature swings during winter since it cuts of most of the Sunlight. Inside I bury the pots in soil and cover with leaf mulch. Conifers also stay inside that structure but lightly covered in leaf mulch. I shovel in snow when I can - it provides water and is also a good insulator. Some plants are overwintered in my unheated detached shed.

    Unheated basement can still be too warm. It needs to be below 45F. Deciduous do not need light but conifers do. They can still photosynthesize above 32F although at a very low level.