Watering Deeply or Surface Watering: Which Method is Best for Your Garden?

When it comes to moisture levels in your garden, looks can be deceiving.

Your soil may appear moist, and even feel moist on the surface, but unless the moisture goes deep enough to reach your plants’ roots, it’s not doing your veggies and flowers any good.

The best way to make sure your plants are getting the water they need is to go deep: Check moisture levels about six to eight inches beneath the ground with your finger. If the deeper soil feels dry, it’s time to irrigate. And when you water, aim for a good soaking that gives water a chance to go where it’s needed.

“When you’re watering plants, they always need to be watered until water runs out of the bottom of the pot or completely covers the entire root ball,” Vego Garden Horticulturist Sydney Fiene said.

Deep watering—long, less frequent watering sessions (one to three times a week, depending on the conditions where you are) that saturate the soil—is much better than short daily sprinklings that do little more than dampen your garden’s surface. The latter approach, known as surface watering, wastes water and can even damage your plants.

Surface watering: a lose-lose for your plants

In many cases, gardening beginners don’t necessarily intend to limit their watering to their garden’s topsoil, they simply don’t realize how soil absorbs water.

Because water tends to be absorbed quickly when it’s first applied to soil, it’s easy to assume that it travels to plants’ roots at the same rapid pace. But the absorption process moves fairly slowly below the ground with soil taking in water one layer at a time.

So, if you lightly sprinkle your garden, your soil might look moist, but again, it likely will be dry where your plants’ roots are.

What will surface watering mean for your plants? For one thing, if your roots aren’t getting the water they need, they’ll be vulnerable to root shock, which can stunt growth and weaken overall plant health.

Surface watering also encourages shallow root growth. Plant roots will remain near the topsoil where moisture is readily available. When that happens, your roots will be more susceptible to drought stress if you miss a watering or two.

Plus, moist conditions at the soil surface can attract pests like slugs, snails, and certain fungal diseases. These pests and diseases thrive in damp environments and can damage or destroy plants if left unchecked.

Surface watering can also result in runoff, where water flows over the soil surface instead of penetrating into the ground. Not only does runoff waste water but it also carries away valuable topsoil, nutrients, and soil amendments (like compost), leading to erosion and soil degradation.

And then there’s the risk of soil compaction: The repeated impact of water droplets on the soil surface can cause soil particles to become compressed, which in turn, prevents your plants’ roots from getting the air they need.

When you water deeply

Deep watering, on the other hand, ensures that your plant roots are getting the hydration they need. Because it encourages the growth of deep and extensive root systems, your plants will be more resilient during periods of drought and better able to access nutrients in deeper soil layers. 

Your plants’ roots will be stronger, too, better anchored in the soil, and less prone to wind damage or toppling during storms.

Deep watering can help you win the war against weeds as well. Well-established plants with deep roots are better able to compete with weeds for water, nutrients, and space.

How to go deep

So, how do you go about watering your garden deeply? First, remember to check your soil’s moisture level with your fingers about six to eight inches down. Water when your soil feels dry.

When you water, don’t blast the soil. That’s only going to slide off the surface. Provide a steady, light stream and give the soil time to absorb it. Try checking the soil’s moisture after about 30 minutes, and if the water hasn’t soaked down six to eight inches, water again and check it again in another 30 minutes.

A few more guidelines to consider:

• Try to water early in the morning or in the evening to minimize evaporation.

• A drip irrigation system or soaker hose will help you apply water directly to your soil.

• Keep in mind that weather conditions, from rainfall to hot, dry weather, might force you to adjust the frequency of your waterings.

A final tip: Topping your garden soil with mulch will help lessen evaporation and keep your soil moist for longer periods. You can also check out Vego Garden's self-watering planters for smaller gardening projects. For raised bed gardening, try using wicking cells to help with watering needs.