It is finally time to plant tomatoes out where I live, YAY!
Here are a few tips for planting tomatoes so they develop a strong root system and help prevent disease.
1. Trim the Bottom Leaves
When you plant your tomatoes out it is best to trim off the bottom few leaves for a couple of reasons. First, so you can plant them deep (keep reading to learn more about this), and second so they don't touch the soil. If the leaves on your tomato plant touch the soil they are more susceptible to disease.
Notice the plant on the left still has all of its leaves, but I have removed the lower leaves from the plant on right has the lower leaves removed.
2. Plant it Deep
Once you have removed the lower leaves from your tomato plant you will now want to plant it, deep. The entire stem of a tomato plant has the ability to grow roots, so removing the lower leaves and planting your tomato deep will give you a much stronger tomato. Your plant will have a deeper root system anchoring it in the ground that way.

If I was planting this tomato in the ground I would have planted it even deeper, so long as the leaves were not touching the dirt.
3. Water from Below & Mulch
Once your tomato plant is in the ground, you will want to water it from below the lower leaves. Watering your plant from below prevents the soil from splashing up and getting on the leaves increasing the risk of disease. Depending on where you live this isn't completely avoidable because of the rain, but there is another way to prevent soil splashing on the leaves, mulch. If you add a layer of straw to the top of your soil it will prevent any soil from splashing up onto your tomato plants when you water and greatly reduce any risk of soil-borne disease. You can use other things to mulch such as leaves or wood chips also.
Follow these simple tips to grow happy healthy tomatoes this growing season.
Happy Gardening!