Urrrrrr....

For the seeds, it's a definite no-go, unless you want to run some significant chances of seed death or seedling death due to dampening-off. The soil from the garden certainly WON'T be sterile. The additional risk is that weed seeds will be present in the soil from outdoors, and until you've got more experience under your belt, you'll have a bit of a time telling the weeds from the veggies that you planted.

Further, if you live in an area with clayey soils, putting these in containers will tend to result in compacted mix, with not enough space for the plants' roots to snake through, breathe, and get adequate moisture.

No, the best thing to do with container gardens AND certainly with seed-starting is to get another bag of a soil-less mix with a base of peat moss. Typically it'll have some perlite, vermiculite, and a few other things. You don't want to tempt failure at this point.

It is possible to sterilize soil by cooking it in an oven, but if your soil is clayey, you still run the risk of compaction and inadequate drainage.

Ok, I'll grab some more starting mix. Thanks!!

Ok, I'll grab some more starting mix. Thanks!!

No as ralleia said, you need a soil-less growing mix for the containers. Very different mixture from starting mix and many brands are available. Growing mixes are more coarse, contain different ingredients and many contain some basic fertilizer as well.

You'll find many discussions on mixes to use in containers over on the Container Gardening forum.

Dave

Sorry, I misunderstood. I need starting mix anyway but i'll also look for some soil-less mix. Thanks!!