Spring is most definitely NOT here, at least for those of us where it snows. Thinking it has arrived can mean the demise of your trees here.
I am VERY concerned this year about the early bud break on most of my trees. We have a significant amount of time before the danger of hard, killing freezes and snow goes away. Given the warm winter, trees are moving at least two weeks early here in Va. That means a seasonal dip into the low twenties or lower can mean death for those trees if they're not sheltered.
Once leaves are visible on buds, even trees with extreme cold-hardiness have lost most of their capacity to survive freezing.
That means, if you live in the Middle Atlantic states or North, if your trees are leafed out they are extremely vulnerable to freezing. You will have to find alternative quarters for them until probably until the middle of April when the last frost occurs.
Spring is always a dangerous time of the year for bonsai. This year it is even more so....