The best time to plant tomato seeds is in late winter, after the last expected frost.

Fill a seed tray with sterile potting soil, which has been mixed up with peat moss. This will help keep your plants moist during germination and also provide them with enough nutrients for fast growth. Don’t forget to add an organic fertilizer that provides all of the essential nutrients for root development, including phosphorous, nitrogen, and potassium. Some types you can use are blood meal or bone meal mixed into the top layer of soil before you sow your seeds.

Make sure there are plenty of drainage holes in the bottom of each cell so excess water can escape easily later on. The cells should also be filled about an inch below the top of the tray with water.

Make a small furrow in each cell approximately ¼” deep and drop one seed into each. Cover these over with ½” of soil mix and press down gently, taking care not to damage any seeds with your fingers. Water them thoroughly, so they are nice and moist but not wet, and place the seeded trays on a heat mat or windowsill where they will receive good light for at least 16 hours per day.

Keep them moist until you start to see tiny leaves appearing from beneath the surface (usually within 3-5 days). Once this happens, it is safe to ease off the watering as long as you do it very carefully – try using a spray bottle for better control.

The seedlings will need adequate spacing to grow and develop properly – around 2″ apart is ideal, although you can get away with 1″ if absolutely necessary. Tomato plants like company and benefit from being kept as warm as possible during the early stages of growth, but outdoor conditions may prohibit this. You can use a heat mat to help maintain the temperature by placing your seeded trays over it or covering them with clear plastic (but make sure there are plenty of holes for ventilation).

Feeding is also important because growing young tomato plants require high levels of phosphorous and nitrogen in the soil before they start flowering. A good liquid fertilizer can be used weekly until you see fruit developing.

The roots are delicate at this stage of growth, so it’s best not to transplant them into individual pots until they have reached 4-5″ in height or more. If you choose to use peat pots, make sure you plant them deeply because otherwise, the roots will quickly grow out of the bottom and become rootbound which can stunt their growth.

Attaching a tomato cage is also very helpful during the early stages of development, especially if your seedlings are quite small. You can either use an existing structure nearby or place some stakes around each one to support them later on when they get taller and heavier, although cages come in different shapes and sizes that may work better for your situation.

Don’t forget to keep your plants well-watered as they develop, and always make sure there is good air circulation to prevent diseases from forming. If you use a wet mop to clean hard surfaces near your plants, try rinsing it afterward in very hot water or with a bleach solution to minimize the spread of pathogens.

By following these simple steps, you should have healthy tomato plants that produce a productive crop in just a few months’ time. Just be patient – although young plants can begin flowering after about 4 weeks, it usually takes another 3-4 before they actually set fruit!