Last year, we purchased two planters at Lowes to decorate the patio for my daughter's graduation party. The tag said that all the plants were annuals. All the flowers died off by October, but the Spike plants still looked good, so I placed them in the shed and forgot all about them. Our shed is not only non heated, but has a few broken windows, so it's not at all warm, but last weekend when I went into the shed to grab some gardening tools, I found the spikes alive and well.
Tough plants, just like their names.