Planting in winter.
We are currently going through a cold period, and ti sometimes go below 2-3 degrees at night, most of spring bulbs are very hardy and will be absolutly fine with mild frost but some varieties of bulb/tubers are sensitive to low temperature.
Bulbs that are quite resistant to frost are: snowdrops, hyacinths, daffodils, irises, cyclamens.
Plant bulbs extra deep, add another 30-40% of recommended depth. Dibber is very handy for that.
Cover your bulbs with old leaves (as bonus it will attract hedgehogs).
If You want to be sure that more fragile bulbs will survive winter You can plant your bulbs/ tubers in a pot and placing them in an ambient room until temperature starts rising again and replant them to planned spot in Your garden or plant them in your windowboxes, baskets, old welingtons and keep them indoor or your greenhouse.
Alternately, you can place them in a tray in a ventilated room. They can hold for a few weeks until planting time.