It's obvious to say plants need both ... their active growth is kickstarted. For this reason, it's important for seeds and seedlings to experience both cold and warm temperatures.

He concluded that the tree grew by drinking water. Students could replicate the experiment ... give the plants different quantities of fertiliser in their soil to test its effect on growth.

Cold weather, particularly frost, causes the water in plant cells to freeze, damaging the cell wall. Frost-damaged plants are easy to spot, their growth becomes limp, blackened and distorted.

The same substance that paints the sky with the Northern Lights also appears to enhance plant growth and insect defense, ...