Water can leave the soil in a number of ways. It may evaporate in the sunlight, run off, or be used by plants. To give your plants a better chance of survival in the summer heat, you can tackle the problem from all sides. Water generously, but follow this with measures to prevent the water from evaporating too quickly from the soil. At the same time, make sure your plants face minimal competition for water by keeping the area around them weed-free. You can even help your plants use the water they do get in the ways that are the most effective for their survival. By removing dead flower heads before plants go to seed, you can save them from wasting valuable water on seed production.