Seedlings you start indoors must be hardened off before being planted because they won’t be accustomed to the cooler and windy weather outdoors. Move them outside to a shady spot for the first few days, increasing the length of time and exposure to sunlight over the following days. Return plants inside each day. Let them acclimate to the outdoors in a cold frame if available or provide sheltered conditions. Assure the plants have adequate moisture as they tend to dry out quickly. After a week they will be ready to be transplanted into your garden.
The timing for planting should be late May for your warm weather plants like tomatoes, melons, cucumbers, and peppers. Plants that tolerate cooler temperatures can go out earlier. If possible, choose an overcast day to set out transplants or try to set your plants out later in the day so the sun will not dry them out. Avoid windy days which will be hard on the plants and rob them of moisture.
Most plants need to be set only slightly deeper than they were in their growing containers. Tomatoes are different. Plant them deeply with much of the stem below the soil, removing leaves and side shoots to facilitate the planting. The “hairs” along the stem will form thin roots providing the plant with additional nourishment and support.
Give transplants a watering of diluted organic starter fertilizer and a couple handfuls of a good compost. Newly planted seedlings require liberal watering. Do not saturate the soil before you put the plants in the ground as the wet soil can compact around the plants and smother or break them.
Monitor the weather after setting out plants. If a cold spell is due, protect plants with a covering such as milk cartons or a row cover. We like to create a low tunnel using wire hoops every two to three feet and draping them with row cover which will keep the temperature above freezing. Once the plants are established and the danger of frost is past, remove the row cover and watch your garden grow!