Of all the junipers, to the best of my knowledge, only Juniperus procumbens "Nana", best known as the Japanese Garden Juniper can be kept indoors.
Now, like any other tree it is the happiest outside and in fact, procumbens can be wintered outdoors in Canada (albeit with some protection). Still, many people who want a bonsai in their home love the look of the Juniper. It's easy to understand because the juniper is the most easily recognized almost archetypical bonsai tree. But it is not the easiest to care for especially at this time of year.
I'm writing this article because I have had more of my customers with happy healthy junipers find that about now - from early March through to early May - their trees can rapidly go downhill. It's because of the changing conditions we experience in our homes this time of year and for our junipers, it's a perfect storm.
- Hate dry air
- Hate wet feet
- Need to dry out (a bit) but not go bone dry
- Brilliantly hide when they are starting to decline
- Store their energy in their foliage
- Need a rest in the winter
So why is this time of year so difficult? Lots of reasons really so here are some of the reasons why your Juniper goes from healthy to dead in (apparently) the blink of an eye.
By March, the air in homes with central heating is super dry. OK, maybe you have a humidifier built into the furnace but are you using it? I have one too, but it never seems to be set high enough. This time of year if you're waking up with super dry sinuses and if touching your cat can be shocking, then your air is very, very dry. Ideally Junipers like 40-50% humidity.
Stronger Sunlight and Under-Watering
As the sun climbs higher in the sky, the rays become progressively stronger and that "coolish" spot that worked up until now might be getting much too warm. Couple that with the dry air. Bad news.
As the sun climbs higher, nudging your tree out of its winter semi-dormancy, its water uptake will increase so that schedule you put yourself on might not be providing enough water. Junipers can handle drying out but not getting and staying bone dry.
Many of the remedies people try to cure the dryness, are ineffective and/or create their own problems. Everyone will recommend a pebble tray. I confess- that includes me, but honestly their effectiveness is seriously limited. If you have a very low-growing spreading tree and a tray that is wide enough to cover the full circumference, the moisture that evaporates from the stones MIGHT do some good to foliage that is close enough, but otherwise, that moisture doesn't stay localized. It evaporates and distributes through the whole room.On the negative side, if you overfill the humidity tray and it covers the bottom of the pot, you'll be denying oxygen to the roots and possibly keeping them wet. Wet feet kill junipers.
Misting. Mist your tree early and later in the day when the sunlight won't evaporate the water immediately. But here is the problem with misting. That Mist will drip off the foliage to the soil surface and very easily contribute to overwatering your tree. Just be aware of that. Be super conscious of the difference between watering the tree and misting the foliage. ( Kinda reminds me of the difference between Church and State).
Just for the record, when you're looking at your juniper watch for small webs in the foliage. This likely means the tree has spider mites, which thrive in dry conditions. If you suspect you might have them, check out this link https://www.zengardenbonsai.com/blogs/growing-on-you/bugs-killed-my-juniper-meet-the-spider-mite/
The thing that I least like about junipers and the reason I might not recommend them to beginners is that they are really stingy with their feedback. When Mini Jades start to dry out their leaves become obviously wrinkled. Chinese elm leaves start to curl when the tree is dry. Stress an elm or ficus and they will drop their leaves- and they do it long before your tree is sitting on death's door. New shoots on many under (and over) watered trees will noticeably droop. The point here is that the trees give off obvious signs that something is wrong.
But not junipers- unless you're watching them like a hawk, they give you nothing, and even when you are watching closely enough to catch that very subtle look of dryness, or a paler shade of green or a slight wrinkle showing up on the stem it's entirely possible that your tree is already past the point of no return.
I have seen instances where what was thought to be a perfectly healthy tree was in actuality quite dead. But that's just a juniper thing and in spite of their perverse tendency not to forgive mistakes, Junipers have and will remain one of the most popular bonsai choices.
Just pay extra attention to it this time of year and try to keep it happy until you can put it outside in May.