You'll want to start your seeds inside, but not until two months before the last expected frost date. Transplant them outside after the last frost date passes.
If your seeds are too close together, they won't grow properly. Their roots will compete for the same nutrients, meaning they won't get everything they need.
For most peppers, leaving about 18 inches between the plants is good. If planting a larger variety, leave extra space between plants, but no more than 24 inches.
Temperature matters. When it’s cooler out, you can go a few days between watering to allow them to dry. When it’s hot, more frequent watering may be necessary.
Don't make the mistake of placing your peppers in a section that is always shaded. Plants grown in full shade turn out smaller than those that receive adequate light.
Start fertilizing your pepper plants about 14 days after seeing the first two leaves. After the initial application, add more fertilizer about once every two weeks.