Are they hardened off yet? Where are you? My average last frost date was 5 days ago as well, but with all the rain I haven't been able to properly harden off the plants, I'm afraid they'll get sunburnt so am still going slow. Plus some nights have been in 40's (followed by 60's) and will be again a couple more times this week so hardening off next week (overnight too) and will probably end up planting not that much before traditional 2 weeks after frost.

My soil temp was 60 the other day.

All I know is that whenever I put in the tomatoes I always wish I had waited. I never do, though, because they outgrow the pots so fast in these middle days of may.

Everything is pretty well hardened off. I move them between my deck and a cold frame. I decided to try starting my own seedlings this year, because my indeterminate tomatoes collapsed all my supports last year - or broke themselves. Figured I would try some determinate, semi-determinate and bush types, so I wouldn't have to buy a $25 super-cage for each one :P.

I'm in Derry, NH.

Quite a bit farther north than I am. Have you been getting all this rain? Making it really hard to harden off - and we're supposed to be getting 3 more days in a row next week - grrr, definitely not going to be hardened off til the holiday weekend!

I can leave the plants out at night starting this w/e, but if I plant any earlier than the holiday I'm going to have to put sunscreen on their little leaves b/c they haven't seen real sunlight yet (had them in shade the first few days, and now weather is Partly Cloudy at best)!

I haven't taken soil temps in previous years, so I don't know if it's warmed up early this year. A lot of people were saying it was going to stay colder since we didn't have a lot of snow to insulate the ground, but that heat wave in March seems to have jump-started things a bit. If your plants are hardened off and they're not going to drown, I'd say put them in, I don't think the cold soil really bothers tomatoes that much, just as long as the air temp is 50 or more. Peppers seem a bit more delicate to me, I'd wait a week longer with them.

Have you planted your beans yet?

Thinking about panting beans this weekend.

I agree, toms can shiver it out a lot better than peppers.

My bush beans shot right up about a week ago.

Yep, it's Go time. My tomatoes have been in the ground for about a week and have already shown some growth. OK for peppers and eggplant now too, but they'll love you more if you give them a blanket of floating row cover. Looking at the long term forecast, I'd say pretty much everything can be sown or transplanted now. I'll bet you could probably even start corn... sow it today to take advantage of the warmth expected this weekend.

I usually get my tomatoes several weeks early and repot them in 4" pots. Easy to bring the flat inside overnight and they double in size by the time I get them planted. If I run a bit slow they don't get too rootbound either. Works for me. Same with the peppers and sweet potatoes.

Soil temperatures depend on much more then your Average Latest Date of Frost.
Moisture levels.
Exposure to sunlight.
Average air temperatures.
If your average air temperature is in the mid 40's for several weeks your soil most likely will be close to that, unless the soil is quite wet or is covered with a mulch material that prevents both sunlight from reaching it and evaporation. Air temperatures can get close to 80 during the day but if they drop into the 20's at night the average will be somewhere in the 40's depending on how long the temperature stayed at each point.
Soil exposed to direct sunlight that is dry will be warmer then the same soil type covered with a mulch. A soil temperature higher then your average air temperature should be telling you that you need to mulch because the sun is causing evaporation of moisture too quickly and is heating that soil to temperatures that many plants do not like.

Well, I did put my tomatoes and cucumbers in, and stick some squash seeds in the ground. We'll see. Still too skiddish to start peppers, so I moved my cold frame to an empty bed. I'll give the soil another week to heat up and plant them under the cold frame. The 2 tomatoes that have been growing under the cold frame for a month seem to be doing really well :).

I was thinking it would be helpful to have some above ground water storage integrated into my drip system. Water coming from my well is pretty cold, it must be keeping the soil temp down. Little solar preheating of the irrigation water couldn't hurt...