A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots.
When to Set out Tomato Plants. The best time to set out tomato plants is after danger of frost, which is usually anytime in April, May or early June. If you started seed indoors, the seedlings should be about 6 to 8 inches tall and hardened off before transplanting outside.
Tomato Plants and Temperature. Most tomatoes are warm season plants and should only be planted after the danger of frost has passed. Tomato temperature tolerance for extreme heat or cold snaps is of extreme importance to the development of blossoms and subsequent fruit set. Blossom drop will occur in the spring if daytime temperatures are warm but night temps drop below 55 F. (13 C.). In the summer when temperatures soar over 90 F. (32 C.) with nights over 76 F. (24 C.); again, the tomato plant will suffer damage to immature fruit or loss of flowers. Additionally, when nights become too warm, the pollen grains of the tomato flower begin to burst, thwarting pollination, hence no fruit set.