Why Do People Water Seeds With Warm Water & Should You Try It?

When you are waiting for your seeds to sprout, a few days can feel like a long time. Finding the best way to start seeds, whether indoors or outdoors, is important. Some gardeners may want to water their seeds with warm water rather than using cold or room temperature to speed up the sprouting process, but does this really have any benefits? It's unlikely, though you could try it if you wanted. House Digest spoke exclusively with our master gardener, Tiffany Selvey, to learn more about this temperature-based watering choice.

"I'm not aware of any scientific studies on the potential advantages to using warm water versus cold or room-temperature water on seeds," Selvey said. "It is possible that watering seeds with warm water right after they are planted could help soften the outer coat, and since the soil needs to be kept moist for seeds to germinate, consistently using warm water could potentially help them sprout faster. " However, she also states that the soil will quickly return to room temperature after watering, so it's unlikely that the temperature of the water will make much of a difference ultimately.

While using warm water is unlikely to help your seeds, there are some potential dangers of super hot water. According to Selvey's exclusive interview with House Digest, using water that is at or close to boiling, can damage the tissues inside your seeds. "A good rule would be if it's too hot for you to touch, it's too hot for seeds," she said.

Using hot water on your seeds won't just harm the seed's inner cells, however; it will also cause the seeds to cook. This, of course, kills the seed and prevents any possibility of them germinating. "Consider some of the foods we eat like corn and beans — these are seeds that end up on our plate," Selvey said. "We don't want to give the same treatment to those we want to sprout." So, keep your boiling water for hot tea and cooking your dinner, and far away from your growing seeds.

Although watering with hot water can harm your seeds, soaking your seeds in warm water, around 100 degrees Fahrenheit, can have many benefits. In Selvey's exclusive interview with House Digest, she shared a study from the University of Massachusetts Amherst, where scientists soaked seeds in water between 115 degrees and 125 degrees Fahrenheit to test the warm water's ability to get rid of pathogens. They found that by soaking the seeds in hot water before germinating, the presence of pathogens on the seeds was decreased. However, it should be noted that this doesn't prevent the plant from getting diseases later in its life.

"On a more practical note for home gardeners, soaking seeds in 100-degree water for a few hours or overnight can really help speed up germination and reduce the spread of pathogens," Selvey said. "This is particularly useful on hard-shelled seeds like okra, nasturtium, and morning glories." So while watering with warm water provides little benefit, priming seeds can improve the germination process. Also, to really get the most from this process, consider how often you should water seedlings altogether to ensure your baby plants can thrive.