May is ideal for planting vegetables and annual flowers that thrive in the heat. Air temperatures are important - night-times should be consistently above 55 degrees F. And so are soil temps - the ground should be 65 to 70 degrees F. Together, with a sunny site, they provide a welcoming environment for edibles like tomatoes, peppers, melons, eggplant, corn, squash, cucumbers, basils and beans. Flowers happy with heat include cleome, cosmos, marigolds, zinnia, sunflowers, rudbeckia and nicotiana. Whether growing from seeds or seedlings, provide regular water as the plants become established; extra water if temperatures soar. Because these are fast-growers, regular feedings with a balanced fertilizer are a must.