You certainly can plant them outdoors; however, if your indoors is air conditioned they may get off to a better start, as they "expect" to sprout and start growing in cooler weather. That's my theory for the suggestion anyway.

Kat - I noticed the same thing, and also am planning on growing those 2 vegetables this fall. I think it's got alot to do with the amount of time needed from germination to maturity, and outdoor temperature. These are both cole crops, and if direct seeded in my region around August 1st - would certainly die, because of the extreme heat. That's why I intend to start them indoors, and transplant them about the 2nd week of September.

I'm sure the heat has something to do with it. It also might be for square conservation. Have summer veggies growing and when you harvest the square you can plant your already started little plants in that square and have a head start on the Fall harvest!

Thanks for the help. It makes sense that they would need cool weather to germinate and grow well. I hadn't thought of that!

Probably has to do with germination temps for those veggies.