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(photo: Karolina Grabowska)

Water too little, and your plants will shrivel. Water too much, and your plants will — well, they still die.

Good irrigation habits are essential to a healthy garden, but hitting the sweet spot can be tricky for beginning vegetable gardeners, who often assume that more water means happier plants. Thankfully, help is out there — and while the best teacher is experience, you can use the following guide to help you get started. 

How often should I water? 

If you’ve ever Googled this question, you’ve probably been advised to give plants an inch of water per week. I find this recommendation academic at best and impractical at worst. 

It’s difficult to measure an inch of water, and gardens simply don’t operate on a schedule — outdoor temperatures, soil type, and plant type all influence the amount of water a garden needs. The same plant may even require different amounts of water at various stages of its lifecycle, further complicating the matter.

While I do recommend researching each vegetable’s unique water preferences, a handy guiding principle when learning how to water is to consider the depth of a plant’s roots. Because soil dries out from the top down, plants with roots close to the soil’s surface — like onions — will need water more frequently than those with deep roots, such as tomatoes. 

I recommend watering shallow-rooted plants when the top inch of soil is dry and deep-rooted plants when the top four inches are dry. My rule of thumb for plants somewhere in between is to water when the top two inches of soil are dry. Figuring out if the soil is dry or moist is simple: just stick your finger in the ground.

How much should I water? 

When it’s time to water, it’s hard to go overboard. Overwatering doesn’t refer to the amount of water given at once but how frequently it’s given. Water until the garden bed is soaked through or water runs out of the holes at the bottom of your pot. Make sure you soak the whole bed, not just the area around the plant, to ensure that the entirety of the garden’s root system is wet.

What time of day should I water?

It doesn’t really matter if you water in the morning, midday, or evening, provided the plants are thirsty. That being said, there are a few caveats. If you water in the early morning, plants may dry out by midday as water evaporates, so you’ll need to keep an eye on them when the hot days of summer roll around. But if you water at night, plants may not dry out quickly enough, fostering disease. That makes watering in the late afternoon the safest bet — but don’t think too hard about it. Choose a time of day to water that works for you. Just be sure to avoid wetting the plants’ leaves to discourage disease. 

Do I really need to mulch? (And what does that have to do with watering?)

Mulch plays a critical role in watering by slowing evaporation and conserving soil moisture. When soil is kept consistently moist, plants can absorb the nutrients they need in a process called transpiration. Mulch also makes things easier on the gardener since a mulched garden requires less water (and less weeding). That’s healthy for your wallet, too, especially when water bills peak mid-summer. 

If you’re still uncertain about watering, don’t worry — you can always buy a moisture meter and cut the guesswork until you master the art. spt

Nadia Nizetich