You're gonna have to hustle in the cold zones. :-)

In zone 4B the ground will likely still be semi-frozen in April. I don't think WOW will help when there are ice crystals still in the soil. Believe me, I know, and it's a bummer.

You could try heating up the soil with clear plastic in early April (solarizing), and hope that warms the soil enough to give you a few inches of unfrozen soil.

Even in zone 5a, which isn't a big difference, the early to mid-April soil, while appearing workable on the top inch or two, is still somewhat frozen and icy down below and inch or two or three. I have had many occasions to optimistically start preparing beds in earlyish April, only to dig up ice crystals and quickly encounter soil that is hard because it's still frozen.

Depending on which zone 4b you're moving to, April can also be very soggy and the "wet" sits on top of the soil because the ground is still frozen below. Heck, it could still be snow covered. Other times, you might get lucky.

Even with WOW, I would be reluctant to put out tomato plants before May. You might be able to do it and have enough luck to get you through, but I would have some backup plants just in case.

Maybe a hoop house or high tunnel or creating raised (unfrozen) beds each year would buy you some time. It would be interesting to hear from others.

Best of luck.

6is/5ish deepening on the whims of MA Nature here..
I am going to try this:
Start under lights in Mid Jan plant in hoop house in Earth-tainers about mid April. Mebbe you can do same and add WOW...(hmm mebbe I'll ad WOW... hmmm...)

I started under lights here Mid feb this year had them planted in ET's June 1st and had a single red jet star tomato July 4th.
I won't put all my eggs in this basket this yr but an experiment I am willing to try.

Never tried WOWs so I can't offer any info on that.

We had a very cold spring up here in Zone 3 and I planted some tomato transplants in early May, a full 3 weeks before the recommended date in a normal year. I covered them with umbrella greenhouses (about 2 ft high, 2-3 ft wide). We then had snowstorms and several nights with temps. below 20 F. During such periods, I draped 3-4 layers of burlap and a plastic tarp over the greenhouses. It was very, very effective at frost protection: the coldest it got in there was 39 degrees and all plants initially survived. Later, many smaller transplants succumbed to rot in the cold wet soils, and lack of sun also played a role. Larger transplants (>6 wks old) survived but did not grow at all until it really did warm up.

So, what really limited plant growth were the cold cloudy days (not the cold nights) and excessive moisture. But, if you have raised beds and/or well drained sandy soils, you may be able to push the envelope with more success than me.

well i live in a zone 4 area that often has only a 90-100 day season. there are things you can do to extend your season.

first and best is a green house for both starting your own plants and growing some plants. this will extend you season to twice as long with out a great deal of extra expense.

we use grow tunnels to cover our field corps at night when there is a danger of frost. we like to cover our tomatoes when the night time when temp go below 50 degrees F. this will allow blossom set and establish a good root system so when the heat hits they really git going. this year we have not had the normal heat and the tomatoes are slow.

we also cover in the fall because we get real nice indian summers after the first frost.

you just need to work at it.

i live in a high mountain valley in central Utah at 5.500 feet.

the extra effort is worth it. last year we got more production after the first frost with out tomatoes that before.

this year i started my corn in the green house and i had corn on the 24th of July. the other gardeners are just getting their first corn now.

you learn tricks and it makes a difference.

this year we did not have a late frost. we watch the rabbit brush for the bright yellow of it's flowers and mark two weeks on the calendar for the first frost.

it is like playing basketball, you take what the defense gives you.

good lock.

Dean

Dean I might be your neighbor! I grew up in Bountiful moved to SLC, I'm moving back to Logan to finish up schooling in Logan. It's good to hear of some sucesses. I was thinking both hoop house and small green house - if finances allow. I'll definitely be starting indoors, just don't want them to bloom until setting out.

Also wondering how getting in the ground w/ WOW affects days to bloom versus, well established - planting very deep.

I know my relatives who have sucessfull gardens don't plant out till memorial day.