How to Start Seeds: A Guide to Growing Plants From Seeds

Starting from seed gives you a wider array of plants to choose from than you get at a nursery, and it allows you to witness your plants’ full transformation into maturity.

1. 1. Select your seeds. In general, the easiest plants to grow from seed are those with large seeds, including peas, beans, corn, squash, melon, and cucumbers. Many crops that grow from small seeds,including most greens, tomatoes, peppers, eggplants, broccoli, cauliflower, and Brussels sprouts, are more difficult. Some small-seeded crops are a bit more forgiving, such as carrots, beets, radishes, and turnips. Flower seeds like poppies, zinnias, nasturtiums, marigolds, and petunias are also wonderful options for novice gardeners.
2. 2. Choose a container. Rather than sowing seed directly in an outdoor garden bed—where birds and any number of other critters may eat them for dinner—consider sowing them indoors. Unlike direct sowing, planting seeds indoors guarantees your seeds will be cozy and safe, allowing you to begin growing in late winter as you wait for the weather to warm. You can start seeds in tiny pots or even egg cartons (as long as you poke drainage holes). Seed starting trays are a convenient option as well; these store-bought seed trays often come equipped with a humidity dome cover and drainage holes. Place a drip tray underneath your container to catch excess moisture and dirt.
3. 3. Add seed starting mix to your container. Seed starting mix is different from potting soil, and instead contains peat moss or coco coir, perlite, vermiculite, and sometimes compost. It provides excellent drainage, makes it easy for sprouts to surface, and is sterile, so you don't have to worry about fungal diseases. Before filling the containers, you must first moisten your starting mix with water. To know if you have the ideal water to mix ratio, tightly squeeze a handful of mix. If water streams out, it's too wet. If no water comes out, it's too dry. If a few drops of water fall out, it's just right. Once your starting mix is properly moistened, fill your containers within a quarter-inch of the top and compress it so it's firmly packed and flat on top.
4. 4. Plant your seeds. Reference your seed packet for instructions on planting depth and spacing. If you've misplaced your seed packet, a rule of thumb is to bury a seed twice as deep as it is long. Once buried, tamp the soil firmly with the palm of your hand. Many types of tiny seeds—including snapdragon, petunia, and lettuce—require light to germinate, so you should leave these on the surface instead of burying.
5. 5. Cover your container. Enclose your seeds with a layer of plastic wrap or your seed starter tray's plastic dome cover to lock in the moisture and heat necessary for your seeds to germinate. It’s usually best to store your container in a warm location that receives indirect sunlight, but always check your seed packet for specific guidelines, as some seeds require total darkness to germinate. To speed up the germination process, try using a heat mat to warm the starting mix from the bottom.
6. 6. Water your seeds. Every day or so, check to see if the starting mix is still moist. If it appears dry, do not use a watering can because it might wash away the delicate seeds. Instead either use a spray bottle to spray a layer of mist over the mix surface or place your container in a larger tray of water so the mix absorbs water from below. As soon as your seeds sprout, remove the cover from your container.
7. 7. Care for your seedlings. This involves keeping them in the correct temperature range according to their seed packets and watering them regularly. Similarly to the germination phase, the seed starting mix should remain moist without becoming oversaturated. Begin fertilizing seedlings once their second sets of leaves are formed. These leaves are known as true leaves and are an indicator that your seedlings are preparing to mature. To fertilize, dilute a liquid fertilizer to one quarter the recommended dosage and administer it from a tray below the seedlings so it soaks up through the drainage holes. Do not use fertilizer if your seed starting mix contains compost, as compost already provides the necessary amount of nutrients.
8. 8. Harden off your seedlings. Hardening off refers to the process where indoor seedlings are gradually exposed to outdoor conditions like colder temperatures, wind, and direct sunlight so that they don't go into shock due to the jarring change in environment. Begin this process about 10 to 14 days before your transplant date by placing your seedlings in an outdoor spot protected from wind and sun for an hour a day. Every day, extend your seedlings' time spent outside by another hour and gradually expose them to more and more sunlight. For hardy annuals, start the hardening-off process just before the last frost so your seedlings can be ready for the start of growing season.
9. 9. Transplant your seedlings outdoors. Once the weather is ideal—generally right after the last frost of the season—and your seedlings have adjusted to the outdoors, it's time to transplant them to an outdoor garden bed or pot. Try to transplant when the sky is overcast, if possible. Reference your seed packet or a seed catalog to determine how much space in the garden each seedling needs to grow. When placing a seedling in its new home, carefully spread out its delicate roots without damaging them. Lastly, water the seedling to allow its roots to properly break into its new soil.

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