Do you plant directly into the soil, or use transplants? I've found that transplants produce earlier. I haven't tried any covering, just the transplants. I get sellable zukes about 1-2 weeks ahead of direct seed.

i grow early summer squash under row covers outside. i transplant also. have not done it in mulch plastic but if you can get the plastic down and give it a few days to warm the soil a bit and then transplant into it that will help get some earlier. run a t-tape down the middle under the plastic. i use 9 gauge wire to form low hoops. i think each wire is 72" and allows a 4' wide piece of mulch plastic to fit under. you will have to remove the row cover when the squash blossoms for pollination.

I grow early cukes and zukes in an unheated hoophouse (what I used to call a high tunnel until I got an actual high tunnel) these are poly covered tunnels about 7' tall so a full sized human can walk into one and stay upright, unlike using row covers/low tunnels.

Start the seeds inside about 3 weeks before they are to be transplanted in the tunnel. After they germinate as long as we are not getting really cold night time temps (under 20F) they go into the hoophouse to harden off for a few days at least. than they are planted into the soil. We usually plant early to mid April, depending on how cold it is.

I think the best season extension tactics are defined by the weather, which of course nobody knows very far in advance. Growing under plastic gives an edge of a few degrees, plus frost protection, but in a hard freeze, most plants are not going to make it without heat, which is expensive.(check out jrslick's recent posts for an idea of what is possible in a cold zone 5 winter) Even greenhouses don't work very well without sunny weather.

Two years ago, I had a warm, sunny spring. I was taking foot-long container cukes to market on March 31st. That is not bad for zone 6. I thought I was a gardening genius, and container plants were the answer to everything. Then last year, the weather was the opposite, cold and wet. By the time it warmed up enough for the container plants to produce, the high tunnel plants under black plastic mulch started to come in right behind them. Instead of two months of season extension with the container plants, I got about two weeks. It was not worth the cost of the containers and media to fill them. So what looked like genius the year before was actually just dumb luck.

We grow zucchini in our movable high tunnels. I plant one of the 16 by 32 tunnels with transplanted Zucchini. We transplant them 1 foot apart and usually start picking 25-30 days after transplanting. Sooner if we have nice weather.

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Sorry the pictures are from different years.

We also grow little pickling cucumbers inside them.

I agree with everyone else, transplant them in, I usually transplant about 2 weeks after they come up. I also germinate inside and try to get them out in the greenhouse ASAP. I have grown them underlights but they tend to stretch out more.

We put them on drip and don't use black plastic for these inside plantings. Since the rows are so close together, it would be really hard to lay the plastic. I am looking at getting some really wide woven fabric that I could reuse every year. Our outside plantings we do use black plastic, then white later in the summer.

I will encourage to use a parthencopic varieties. Perfect Pick is one and Partenon are two green varieties and Cavali is a light green variety. I like the light green, but they don't sell the best, but they do get people to stop and look.

Thanks everyone, jrslick curios about that high tunnel what did you build it out of? rough cost to build one?

You may want to do a little pencil pushing before you fill a high tunnel with Zucchini. Ask yourself what your market price expectations are and even more important, what quantity will your market handle. This is one crop that I can sell a few bu. at every market but usually end up giving most to the local Food Bank or composting. They are heavy to handle and If you have to give most away you may regret overplanting.
For an earlier crop I'd definately plant thru black plastic, even within a tunnel or under row cover. I have switched to direct seeding lately b/c in warm,moist soil those seeds should be up in 5-6 days. Shop for earlier varieties and compact bush types that lend themselves to closer spacing.
Be prepared for a daily picking routine and do as much as you can to keep your harvest fresh and appealing. Those qualities will continue to bring customers back which should be your ultimate goal.

I agree Bmoser. I am getting $1 a piece for these early zucchini and I almost always sell out. The next planting goes outside, but these early ones help establish a customer base. They start buying mine, then they will always buy mine. It has worked for the last 4 years.

Jay

This is how warm it was at noon in my high tunnel yesterday. It got up into the 90's by mid afternoon and that caused the lettuce to germinate. It was in the high 20's outside when I took this.