To water... or not to water

Temperatures are climbing in Missoula. By the end of this week, it’s forecasted to reach nearly 100 degrees! It looks like this season is gearing up to be hot and long (by Montana standards). You know what that means – our garden plants are going to be extra thirsty. Temperatures over 90 degrees will cause plants stress if they aren’t watered enough.
Well, let’s be realistic - watering your plants is important no matter what the temperature is. Plants need water to help them stay upright and grow taller, to photosynthesize, and to move nutrients from their roots to their leaves and flowers. Water is one of the essential ingredients for plant survival, and can be the difference between a plant that looks and produces well enough and a thriving plant with generous production.

How do you know when your plants have enough water, you ask?  Well, for one, they’ll be green and perky. But that’s not all to look for.

Well watered tomato plant

The best way to make sure your plants get enough water is to water them deeply. Plants take in water (and other nutrients) through their roots. So you want to be sure to thoroughly soak the entire root zone of your plants.

At first, seeds and seedlings have no roots or little roots, so more frequent, shallower watering works well. But as those plants grow bigger, it becomes more and more important to water down to your plants’ roots. Deep watering  encourages the plants’ roots to grow further down into the soil as they seek water. Larger root systems help plants to absorb more nutrients and to better withstand drought. Therefore, mature plants benefit more from deeper, less frequent watering.

This also means that different areas of your plot may have different watering needs, depending on what you have planted. If you just planted a succession of beets and carrots, those seeds and seedlings don’t need to be watered as deeply as your first succession of those crops, or any other maturing plants.

Ensuring You Water Deep Enough

There are a few tricks to make sure you are watering deeply enough.

First things first, don’t water faster than the soil can absorb it. Some soil types can absorb water faster than others. If water pools up quickly in your plot’s soil, it can be best to lightly water, wait a few minutes (perhaps to water a different set of plants), then lightly water the same plants again, and repeat until you’ve watered enough. Thoroughly watering your plot in the middle of summer is definitely a time commitment (hopefully an enjoyable one), but it can also serve as a time to observe what else may be going on in your plot. How are those carrots coming along? Do my tomatoes need some extra love this week? My radishes will be ready to harvest soon! 

KimGilchrist_Water_2015 (2)

How to: checking your water level. You can use a trowel to dig 5-6 inches into your soil and check the water level. You want the soil that is 6 inches down to be wet enough that if you squeeze it in your hand you can see your finger impressions in it. Less reliable is the finger test. Stick your finger deep down into the soil to see if it’s still wet a few inches down.

Know the watering needs of your plants. Most plants perform best in soil that is kept moist, but not waterlogged. Some plants, however, prefer the soil to be completely dried out before being watered again. In our dry climate it’s best to err on the side of keeping the soil evenly moist, but if you really want all your plants to thrive, learn about their individual watering needs.

Other Techniques for Maintaining Water Moisture

Mulching is a tried and true technique that improves water retention by reducing evaporation from the soil. Use some leftover straw from last year around your plants that really need moist soil. Or bring in some extra so you can mulch your entire plot if you find your soil doesn’t maintain its moisture so well.

Proper plant spacing can also be used to help maintain moisture. Too many plants in a small space will increase competition for precious water. Too much space between plants will expose more soil to the sun and air and increase evaporation. The best spacing (usually indicated on the back of a seed packet) minimizes competition while providing a shade canopy over the soil that will decrease evaporation.

Building your soil will also improve your soil’s moisture retention. Rotating your crops, adding compost, and being sure to tread lightly in your plot will improve your soil structure over time. Water can better infiltrate light, porous soil than it can compacted soil.

Do you have any other tricks to maintain the moisture in your plot or make sure you are watering enough? Please share in the comments below!