Is there a benefit to watering tomatoes with optimal pH level in the water?

by B.T.
(Leander, TX)

I just received some heirloom O.P. seeds of a variety (don't know the name, but can find out) received from a friend in OH who has been raising them successfully for years. According to him, it is a variety thought to have been extinct for 50 years. All hyperbole aside, his crop yield and photos of his garden appear somewhat akin to the stands of row crop corn I recall in IL in the early '60's on a trip there as a child. So I’m starting and growing them.

Here's my question... I have an Enagic water ionizing machine that allows me to produce multiple levels of pH water that I can closely monitor with my laboratory grade test meters.

What, if any, benefit could my plants realize (from starting through production) by watering them with water at the optimal pH level for tomato soil? I am going to germinate some of the seeds using the moistened paper towel method using 11.5 pH ionized water, which has proven incredibly effective in rapid germination all other seeds to date (except tomatoes, which I have not had the machine long enough to try out). Our tap water here in Leander is horrible, so I have the machine at our business in Austin, where I will most likely raise the plants in 5 gallon containers out back of the shop -- probably too small for this variety, but I don't have time to prep a ground garden (except maybe over the septic drain field...), but will try anyway.

The City of Austin delivers water to the tap at our shop at 9.8 pH (!!!) to cut down on the deterioration of old water mains from the normal delivered pH of municipal water supplies in our aquifer region of 7.7, which does no favors to trying to maintain a slightly acidic tomato soil pH. The ground water comes out of the aquifer at 8.3 + (very hard) and the city boosts it to 10.1 using a single stage softening process (probably lye), then uses Calgon buffers to get it down to the 9.8 pH delivery level. (The EPA disallows the sale of bottled water at levels exceeding 8.4 pH ... go figure.)

I can produce sufficient water at an optimal pH with our machine to keep the plants nurtured throughout their growing season, but I'm just wondering if I'm over thinking the issue, or if I might have stumbled across a godsend to the success of my plants...

Fortunately, if I strike out this year, I can always get more seeds from him next year...

Admittedly, I'm getting kind of a late start on this particular project for our growing season. I am only trying this variety at our business location to avoid cross pollination from our "store bought" seedlings already going strong at home, and to avoid the sprinkler system foliage exposure.

Thanks in advance for any and all suggestions, interest, or musings.


Dear B. T.,

We at Tomato Dirt will be curious if you find out the name of the “mystery heirloom”! Who knows, you could be a part of a new discovery in the tomato world.

As far as the pH levels as you water …

Depending on what seed starting mix you use, most of those commercially-prepared have a pH around 5.5. (Obviously, you should test it to be absolutely certain.) Tomatoes grow best in slightly acidic soil with a pH level between 6.0 and 7.0 – optimum is between 6.5 and 7.0.

As you water the seed pots and your seedlings with tap water (which in many cases is quite alkaline as you pointed out – and specifically, yours very much so), the pH in your pots gradually increases. Controlling the pH of your tap water makes sense as you start tomato seeds. But it works hand-in-hand with the pH of the potting mix, too.

By the way, pH is not only important for germination but also a tomato’s early development. As pH rises, so does the seedling’s susceptibility to damping-off disease. If you know the pH of your tap water and adjust appropriately as you are able to do with the ionization machine, you increase your chances of growing healthy seedlings.

When it comes to planting, continue to maintain a pH level between 6.0 and 7.0 in the soil. Since you’re growing your tomatoes in containers you can control the soil. (Use a simple but accurate pH test kit to periodically check the soil's pH level.) If your soil’s pH isn’t within the optimum range, make proper adjustments. To lower your soil’s pH, work sulfur into the soil. To raise your soil’s pH, work lime into the soil.

Your water’s pH can help, too. But don’t rely solely on either the soil or the water to maintain the most favorable pH for tomatoes. They work together.

With your machine and your know-how, you can help your soil and your water work hand-in-hand to create the best possible home for your tomatoes and grow a healthy crop of those exciting heirlooms this year!

Good luck and happy gardening!
Your friends at Tomato Dirt