Tomatoes are the drama queens of the vegetable garden. One minute, they’re growing along nicely, filling out with flower clusters and beautiful fruit; the next, they’re throwing a full-blown tantrum. Yellow leaves, cracking fruit, blossom end rot, it’s never just one thing with these guys.
But oddly enough, sometimes the root of the problem (pun totally intended) lies in how we water them.
Let’s make sure your watering practices aren’t harming more than helping your tomato harvest.
Cultivated to Be Finicky
Unlike their scrappy native cousins in South America, the cultivated tomatoes we grow in our backyards have been bred over the centuries to enhance qualities like flavor and size. Unfortunately, that means many of their tougher characteristics, which help them survive, have fallen by the wayside.
This means we need to be spot on when caring and providing for them.
Tomatoes are heavy feeders, and, along with the right nutrients, they also require plenty of water to continue growing and producing fruit over the course of a season. But tomatoes are notoriously finicky about how they are watered.
1. Watering Too Often
You’ve likely heard the advice that tomatoes should be watered deeply. While this is true, there’s a second part to that wisdom that’s just as important, deeply but not frequently.
You shouldn’t be watering your tomatoes daily. You want to encourage your tomato plants to push their roots deep into the ground. The further down the roots grow, the plant has more protection in drought conditions, as they will have access to water much deeper in the ground.
When you water too often, the roots do not need to grow deeply. Then, the second hot weather hits, they don’t have access to the water further down in the soil, and the plant suffers.
Overwatering your tomatoes can flush nutrients out of the soil, causing yellow leaves and sparse fruit production. If you’re too heavy-handed, you can even drown the roots, causing root rot.
Of course, there’s a caveat. If you’re growing tomatoes in containers, rather than directly in the ground, you’ll need to water them more frequently. This holds especially true during periods of extreme heat or drought.
When I was gardening on my second-story balcony, there were times in the height of August when I had to water my potted tomatoes twice a day.
Whether you’re growing them in the ground or containers, a good rule of thumb is to water whenever the top two to three inches of soil are dry. Stick your finger in the ground to check.
2. Not Watering Deeply Enough
Watering deeply is the second piece of advice that often gets overlooked. I get it, when you’re under the baking sun or fighting off mosquitoes, it can be tempting to give your tomato plants a little sprinkle and call it a day. However, this only trains the roots to stay near the surface, where they dry out much more quickly.
And in the end, you’re setting yourself up for disappointment.
I am a huge fan of soaker hose or drip line for watering tomatoes as it’s much easier to give them a thorough soaking that reaches 6-8 inches below the soil. If neither option is feasible for your setup, be sure to water at the base of the plant and thoroughly soak the surrounding ground. Mulching around your tomatoes will help prevent evaporation and retain that precious water in the soil, where the plant can utilize it.
3. Watering at the Wrong Time of Day
I used to ignore this advice, but I learned the hard way. There’s a right time and a wrong time of day to water, and it plays a significant role in evaporation and disease prevention.
If you water in the afternoon, you’ll lose a significant amount to evaporation. The sun is at its highest and strongest, so rather than soaking into the ground, you lose some to evaporation.
On the other hand, if you water in the evening, then you’re more likely to encounter soil-borne fungal and bacterial diseases. These guys thrive in cool, damn environments and freshly watered tomato plants after dark become prime real estate.
The best time to water your diva tomatoes is first thing in the morning before the sun is too strong. You reduce evaporation, allowing the soil to dry thoroughly during the day, which in turn reduces the risk of disease.
4. Avoid Splashing the Leaves
Plenty of tomato sadness lurks in the very soil in which they are growing. When it rains hard or if you get a little overzealous with the spray attachment on the hose, microbes in the soil get splashed onto the lower leaves of the plant. Sometimes that’s okay, and sometimes it’s not. It all depends on what’s currently lurking in your soil.
Again, this is why I’m a huge fan of drip lines and mulch; they keep soil-borne diseases at bay. If you really want a gold star in tomato disease prevention, follow the 1/3 tomato rule. (You can read about it here.) It makes your tomato-growing life so much easier.
5. Be Consistent! B-E Consistent!
Sorry, now and then, my days as a high school football cheerleader resurface.
Here’s the thing. For beautiful, juicy tomatoes, consistent watering is essential. Too much, too fast and they swell and crack. Not enough, and you get smaller, less flavorful fruit.
Don’t rely solely on the rain. Get out there and stick your finger in the soil to check every few days. Watch your forecast and plan accordingly.
Tomatoes prefer slightly damp soil, not completely dry or completely soaked roots. Aim to be consistent and you’ll do just fine.
6. Don’t Skip the Mulch
Mulch keeps the moisture in, the weeds out, and the soil temperatures regulated. It also prevents soil from splashing up on your plants, lowering your risk of disease. It cuts down on so much extra work.
Lay down a good 2-3 inch layer of organic mulch around your tomato plants. Straw, shredded leaves, or untreated grass clippings all work great. Just keep it a few inches away from the base of the stem to prevent rot.
Bonus Tip: Pay Attention to the Weather
Hot, dry, windy days will dry out your soil faster than you think. And just like me, tomatoes get cranky in the heat. If you notice the leaves starting to droop by midday, don’t panic. They’re curling in to slow evaporation. It’s normal tomato behavior. But if they’re still droopy the next morning, it’s time to take action.
In cooler, wetter weather, lay off the water. Tomatoes hate soggy soil, and overwatering is just as harmful as neglect.
Watering tomatoes isn’t rocket science, but it does require observation and consistency. Once you dial in your watering routine, your tomatoes will reward you with juicy, flavorful fruit and fewer problems overall.
And if all else fails, remember that tomatoes will forgive a watering mistake here and there, just not all six at once.
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