Answer: Seeds will take a week or two to come up, depending on the weather, and how warm the soil was when you planted them, and how deep you planted them. So it is too early to look for sprouting. While you wait, make sure the soil does not dry out. Check it with your finger and if it feels dry, water lightly to keep the seeds moist until they come up.
The marigolds and sunflowers should be fine, however the petunias may be problematic. These take a long time to grow to the usual transplant size and so are usually started indoors under controlled conditions about 12 to 14 weeks before your last expected spring frost, then they are set out as small plants. Even if your petunia seeds germinate, it will take several months before they will bloom.
It is always difficult to wait impatiently for the seeds to grow, but they usually do come up sooner or later. I hope this helps.
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