I only do tomatoes from seed and will not start them for several weeks yet. A good friend at church who is now 82 started his peppers last week. He grows 100s of pepper plants, buys his seed in 500 seed packs. Peppers take a little bit longer to germinate than tomatoes so its OK to start them a little earlier. He starts them indoors and then moves them outside to a home made green house he constructed from an old metal swing set and plastic. It seems to work well for him. I don't grow onions from seed, I buy onion sets and just plant them. They are only about $1 per pound and I plant 3 pounds. So if your planning on putting your plants out in the garden along about Memorial Day then it isn't too early to start peppers, but I would wait a bit for your tomato seeds. Just one old guys opinion.
You can push the season all you want, but tomatoes don't grow well until the nights get hot.
PS, I am from up North of the Mason Dixson Line, so if you are a bit farther south than I am you can adjust accordingly.
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