wiswash said:
Living in Wisconsin we have a frost danger til late May. If I want to plant tomatoes in garden about May 20 then when should I start my tomatoes seeds indoors.
Six weeks before is usually good -- although it depends on what temperatures you grow the seedlings at and whether you use a heat mat at any point. (Cooler = slower; but tomatoes generally
do better if you grow them rather coolish once they have a pair or two of true leaves)
I would err on the side of earlier rather than later start with tomatoes, too -- because if they get too tall and gangly while waiting to go outside, you just plant them extra-deep (or at a 45-degree angle) with much of the stem buried (strip the leaves off the part that will be buried, of course) and just 3-4 pr true leaves showing aboveground, and the will grow extra roots from the buried stems and actually end up as very robust healthy plants.
You might seriously think about wall-o-waters too (or the red version, whatever its brand name is). They can let you put tomatoes out MUCH earlier which here in the north can make a big difference in your first tomato date and your total harvest. I trust them down to 20 F (they may be ok a bit lower than that, even, especially if you chuck a bedsheet over 'em).
So if you have any daily weather records for your house for the last few years, see when you no longer seem to get temps below the low 20s, count back 6 wks from *that*, and you can start a few seeds *then*.
Do make sure to pre-warm the soil if you do this, either by setting out the wall-o-waters a couple weeks early or (my preference) covering that part of the garden with clear plastic sheeting for a couple of weeks.
Wall o waters ROCK for getting earlier (and more) tomatoes in these colder zones, though!
Our last frost here, because this property is in a low cold-trap spot, is generally during the first week of June; but using wall-o-waters I can safely put tomatoes into the ground in mid to late April, and get considerably earlier harvest
Good luck, have fun,
Pat