It's not so much the air temperatures as the soil temperatures that are important. Below I've linked Johnny's Selected Seeds online catalog. One of the things I love about this seed company is all the information they give you on growing. If you go to page 31, there is the guide to cukes. They give needed soil temperatures for direct sowing, including a chart of temperatures vs % germination and the statement that cuke seeds will not sprout if the soil is below 50 degrees and will only sprout very slowly at 68 degrees. They give similar type of info for squash and pumpkins on pg 96. At this time of year you'd be better starting them indoors where the soil will be warm enough for them to germinate, and then plant them out in a few weeks. You may find that your beans aren't too happy either. Another option would be to cover your soil for a couple of weeks with plastic sheets or spunbond row cover so that it warms up enough and then plant. Or do both so that by the time your potted starts are ready to plan, the soil is very warm.

Here is a link that might be useful: Johnny's Online Catalog

Absolutely, nhbabs. I planted zucchini and stringbean seeds over 2 weeks ago and nothing is showing yet.

Carol

I usually wait on Cukes until it warms up. Direct sow them around the same time I direct sow the Zinnias, which is June 1st. In fact, sometimes I wait until later, because my favorite summer salad is cucumbers, tomatoes, sweet onions, basil and olives. YUM! Anyway, the cucumbers grow fast and are always ready before the tomatoes and it's nice to have them ready around the same time.

nhbabs is absolutely right - it is more a function of soil temperature. You can pick up a soil thermometer for under $10. And they are real easy to use - plunk the thermometer into the soil, wait a few minutes, and read. I usually test multiple places in my bed.

Are cucumbers susceptible to squash vine borer? If so, I read last year to wait until 1 June to direct sow squash seeds. Apparently the plants will be too small when squah vine borer moths arrive, and thus your vines will not succumb to the borer. And lets be honest - who will complain about a slightly shorter zucchini season?

Thanks all. I have used the Scheepers catalogs info on soil temp, but I have been to lazy to actually see what that temp is :) I do have raised beds and did insulate them with clear plastic for a few weeks at the onset of spring. I suppose I can wait a little longer. I figured with the beans I would just out them in and let them come up when they're good and ready- with my experience with beans they just grow- no matter what you do to them! I will wait a bit longer on the other stuff- and being that all my curcubits were desecrated by SVBs last year, this year I am using Envriomesh screening to protect them. It's nice stuff. I have it on my cabbage and cauliflower now. I took it off one day and within 5 minutes saw a cabbage worm moth flying around, so on it stays!