Will "winterkill" crops reliably die in USDA zone 8?

Question

I am in USDA zone 8 (specifically 8B, US Pacific Northwest region). I am looking to plant some cover crops (if it matters, specifically daikon radishes) over the winter with the idea that they will winterkill and begin decomposing by the time I start to plant in the spring.

In my zone we typically do not get any hard frosts. Once or twice each winter it gets down to about 25 degrees Fahrenheit (about -4 degrees Celsius) overnight, but that is about it - it typically stays above freezing. Sometimes it snows, but even then it is just barely below freezing.

Can I rely on the winters in my zone to actually kill my winterkill cover crops? I'm assuming this is probably dependent somewhat on the species of plant, but in general, if a plant is said to "winterkill" can I assume it will do so in zone 8B or do I need to find out exactly how non-hardy it is to be sure that it will die over the winter?

Answer 1

Whether your winterkill crop will actually be killed by your winters is entirely dependent on the species and hardiness of plant you choose to use, so you can't assume that the description 'winterkill' means it will definitely die where you are.

Daikon radish sown in fall in your area is unlikely to be killed over winter; there is quite a bit of information in this link re winterkill crops, as well as embedded links to various charts which might be helpful http://notillveggies.org/2014/10/13/when-cover-crops-die/