How to Start Seeds Indoors in 8 Simple Steps

Before anything else, decide what you want to grow. Look for seed packets labeled "ideal for starting indoors." Some vegetables and herbs, like tomatoes, peppers, broccoli, lettuce, and basil, do particularly well when started inside. Make sure the seeds are fresh and within their viable planting window, and check the back of the packet for recommendations based on your growing zone.

You don't need anything fancy to start seeds. Use seed trays, small pots, yogurt cups, egg cartons, or even cut-off milk jugs — just make sure whatever you use has drainage holes at the bottom to prevent root rot. Place a tray or plastic lid underneath to catch any drips.

Regular garden soil is too heavy for seedlings — it tends to compact and can contain pests or diseases. Use a seed starting mix, which is lighter, drains well, and helps delicate seedlings grow strong roots. You can find it at garden centers or make your own with peat moss or coco coir, vermiculite, and perlite.

Before adding soil to your containers, moisten the seed starting mix so it's damp but not soaking wet — think of it like a wrung-out sponge. Add the damp mix to your containers and gently pat it down without compacting it too much.

Read the seed packet to determine how deep to plant your seeds — a general rule is to plant them twice as deep as they are wide. Press the seed gently into the soil and cover it lightly. You can plant two or three seeds per cell or container, then thin them out later if needed.

Seeds need warmth to germinate — most do best between 65 and 75 degrees Fahrenheit. If your home is chilly, use a seedling heat mat to warm the soil from underneath. To maintain humidity, cover the trays with a plastic dome or plastic wrap until the seeds sprout, then remove the cover once seedlings emerge to prevent mold.

After your seeds sprout, they need lots of light. A sunny windowsill might work, but many gardeners use grow lights to ensure their seedlings get enough brightness. Place lights about 2 to 3 inches above the seedlings and keep them on for 12 to 16 hours a day — without enough light, seedlings can become leggy and weak.

Keep the soil moist but not soggy, using a spray bottle or gentle watering can to avoid disturbing the young roots. As seedlings grow, thin them by snipping the weaker ones at the soil line so the strongest plant can thrive. Once they develop two or more sets of true leaves, start feeding them with a diluted liquid fertilizer.

Bonus tip: before moving seedlings outdoors, harden them off. Start by placing them outside in a shaded spot for a few hours each day, gradually increasing the time and sunlight over a week or two. This helps prevent shock and gives your plants the best chance to thrive in the garden.