Warm El Niño weather allows cannas and other tender bulbs to stay in garden soil longer

The long stretch of warm weather, courtesy of El Niño, has kept our southeastern Michigan garden soil warmer than we would expect for this time of year. That means plants that would normally have been freeze-killed by now are still alive.

A few weeks ago, I blogged about digging and storing canna and dahlia roots. Both dahlias and cannas are tender plants that are killed by cold winter temperatures. The tops are the most susceptible parts of the plant that die back at the first hard frost in the fall. But underground, the roots can still remain alive for some time.

While I have all the roots in storage that I need for next year’s garden, there is an area in the front flower garden where I didn’t get a chance to dig up the remainder of our bulbs.

This spot has a southern exposure so it gets a little bit more solar gain than other parts of our yard. The sun is quite low in the sky this time of year and doesn’t provide a lot of heat, but it does provide some, and the southern slope helps absorb solar (heat) radiation significantly more than a north-facing slope.

We like to leave pretty much all of the garden debris in place in the garden over winter to provided seeds for birds and shelter for beneficial insects.

This spot is also mulched with pine needles which provides a blanket of insulation helping to prevent the soil warmth from radiating out into the air. This keeps the garden soil warmer than it otherwise would be if it were bare.

On a sunny day shortly after Christmas, just few days before the New Year, I was looking at the garden and noticed the dead canna and dahlia stems laying on the ground. It dawned on me that it hadn’t gotten cold enough to freeze the soil yet.

I broke out the garden forks and, with the help of my daughter, dug up the tubers. They were in perfect condition. The soil temperatures were still in the forties providing just the right the conditions for the bulbs to remain in great shape in the soil, right where they were growing.

I had an extra plastic storage tub, so in they went and are now in a protected spot indoors where they will be over-wintered until spring.

By far, this is the latest I have ever dug tender bulbs.

If you grew some cannas, dahlias or other tender bulbs this past season and didn’t get a chance to dig them up, you still may be able to salvage them, especially if they are in a sheltered spot where they received some sun. Don’t wait too long though, the weather forecast is for normal temperatures finally returning and the roots and tubers will soon freeze.

Although the new year has just started, spring will be here before you know it. I’m looking forward to a bountiful gardening season, I hope you are too.