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.
Starting seeds indoors six to eight weeks before the average last spring frost date, or directly sowing them in the garden after the last frost date once soil temperatures reach 60 F or warmer will produce seedlings. A temperature range of 65 to 75 F is best for tomato plant growth. When temperatures drop below this range, growth slows. Tomatoes will grow in temperatures warmer than 75 F, but you'll need to water more often to prevent wilting.