Egg overwinter on the crooks and crannies of plants.

Since you will be getting rid of the plants and the soil, and washing the containers (because of the blight), you need not worry about reinfecting next year's crop with this year's pests. If that's what you were wondering about.

However, you STILL have to worry about whitefly because brand new ones will find your plants next season. Keep a close eye out, early in the season, and have your spray bottles ready. Neem can discourage feeding and egg laying.

White flies are closely related to Aphids, Mealy Bugs, and scales, and because of gross overuse of most insecticides to try and control them they have become immune to many. Keep in mind that spraying any poison, Neem products included, will kill off the predators of White Fly as well as the White Fly, so many other control straegies need to be used that will not do harm to the predators. This link may be of some help.

Here is a link that might be useful: White Fly

What you have are probably good old common greenhouse whitefly. The eggs probably came on some plant material you have purchased and brought into the vicinity. I have on occasion seen GH whitefly on my vegetable crops, but am sure they got innoculated from greenhouse grown plants somewhere along the line.

I have seen them amassed in weeds in fallow greenhouses in early winter. So, I know they can survive a certain amount of cold If your winter temps fall below twenty one degrees for any sustained periods of time all stages should succumb to winter kill. So, like rhizo says, if the plant material is gone, so are the pests. They will not be in your soil, nor on your pots.

This is not a typical pest for temperate zones because they do not overwinter outside. They have to be introduced on material from a warmer climate or a greenhouse situation.

I have seen whitefly year after year in my locale, even though the winters have dipped to 0° two or three times. Fortunately the infestations are localized. The problem becomes that folks keeping indoor plants (that go back outside in summer) do not recognize or control their whitefly infested plants and trash them as they should, but let them overwinter keeping a new infestation ready and handy for outdoor plants the next season. They wouldn't be here in zone 6A if that wasn't true.
hortster

Exactly. They carefully bring them back in their homes or greenhouses to continue the cycle. Then wonder why they always have to fight whiteflies in their hobby greenhouses. It doesn't take much to flip a leaf over and look for the eggs or crawlers. They are like tiny grains of rice and feel glued on. That's why I politely refuse to winter over anyone's pets in my heated greenhouses.