Ideal pH Range for Container Tomatoes?

[rnewste]

I'm growing in 31 gallon DIY Earthboxes using Miracle Grow, as well as Sta-Green potting mixes (for trial comparisons). I want to keep all variables such as pH as consistent as possible in doing the "A / B" test of the two potting mixes

Right now, the Miracle Grow mix (with 1 cup of lime added a month ago) is showing approx 6.5 pH. I know you cannot control it to a specific number throughout the growing season, I just wanted advice on the optimum pH range for tomatoes. I've searched a number of threads by GIZZARD and others, but could not seem to find a recommendation on an ideal pH range for container growing.

thanks,

Ray

[feldon30]

Well, I always add dolomitic lime and now I know why.

[rnewste]

Hi Morgan,

Can you please be a bit more specific on your comment: "now I know why". Does the reading on my meter tell you that you would add more dolomite lime if that was the reading you saw in your garden??

Ray

[amideutch]

Ray, FYI this is one quote concerning ph for tomatoes.
"A pH of 6.5 is the point where nitrogen, phosphorous, potassium (N-P-K) and trace minerals are most available to majority of plants. Tomatoes will grow with a pH range of 5.8 to 7, and although they are adapted to slightly acidic soil, they will grow best near the 6.5 pH mark". Whether they are grown in the ground, in a container or hydroponically the ph requirements for tomatoes remain the same. Ami

[amideutch]

Ray, a blurb about Dolomic lime and it's use and lime in general. Ami

You will find reference to at least four kinds of lime in agriculture: crushed limestone [Calcium carbonate (CaCO3)], dolomitic lime [Calcium-magnesium carbonate (CaCO3--MgCO3)], burned or quick lime [Calcium oxide (CaO)], and slake or hydrated lime ]Calcium hydroxide (Ca(OH)2)]. Of these, dolomitic lime appears to be the best additive to raise pH and promote growth.
This is because dolomitic lime includes manganese and because dolomite lime acts slowly and continuously, and hydrated lime acts almost instantly. Use hydrated lime instead of dolomite lime for faster results, but don't use too much; you can create toxicity problems, which won't arise with dolomite lime, by using too much hydrated lime. Always use fine dolomite lime, since coarser grades take years to have a substantial effect. Dolomite lime is available at most nurseries.

[peebee]

Ray, when you say you added 1 cup lime a month ago, how did you add it to your container? Did you sprinkle it on the top and watered it in, or mixed it in from the top with a small spade? I have never used or seen this dolomitic lime in nurseries, is it in small boxes or in those larger cubic size bags near soils/fertilizers? Wouldn't it be easier to add it to your container soil mix before planting the tomatoes, or is that a no-no? And is it organic?
So many questions, inquiring minds want to know...

Suzie

[rnewste]

Suzie,

The EarthBox video recommends adding a cup of Dolomite Lime before first planting to the potting mix. I found this package at our local nursery Summer Winds at $5.00 per box.



Here are the contents:



In a 'Taner where I recently used 2 cups, I am getting a 6.9 pH reading on the meter. I realize these inexpensive pH meters are not "absolute" but I use it as an indicator in pH change.

In one of my EarthTainers, I am going to do an "A/B" comparison with Dolomite Lime in side "A", and Epsom Salts in side "B", to see which product is more productive this year.

I followed the EarthBox instructions and sprinkled it on the surface, and dug it in to the top 4" of the potting mix. I am adding it in a few weeks prior to planting the tomatoes, as it takes several weeks in the soil to "do its thing".

Ray

[peebee]

I know two places where they sell this EB Stone brand, I'll look for it tomorrow. Guess I never looked for lime in the past cuz our garden soil here is definitely NOT acidic, but I guess potting soils are a different matter. I'm so glad I'm reading this Container forum, as I am going to grow more in containers from now on. Just always bought potting mix that contained nutrients already(organic) but I will be making my own mix in the future.
It will be interesting to hear of your tests with lime and Epsom salts.
Thanks for the lime info Ray.

Suzie

[rnewste]

Suzie,

In the EB where I added 2 cups and got a 6.9 reading, my "nose" is telling me that 1.5 cups of Dolomite Lime is the right amount to hit approx 6.6 to 6.7 pH for my tomatoes this year. My 'Tainer holds about 2.7 cu. ft. of potting mix, for reference.8)

Ray

[peebee]

Hi, I finally went to buy this lime but instead of the nursery that carries the EB Stone, I went to OSH's instead as it was nearer. They only had Whitney Farms Prilled Dolomite Lime, and it was $7.00. Says on box that it is finely ground lime that is "prilled" to be easy to use thru a spreader. I have not opened the box in case I have to return it, but it sounds like they are small pellets.
Could I use this instead of the "Agricultural Lime" Ray has posted a pic of?

Suzie

[amideutch]

peebee, your whitney farms prilled dolomite should work just fine. It will break down once its watered. In fact it will be easier to apply than the powder formula. Ami

[REDCLUSTER]

rnewste,

I would be more concerned with the pH of your source water than that of your media. The source water will inevitably change your media pH over time. Be sure to check the pH with and without your fertilizer.

It's much easier to start with your media at 6.5 and water with a solution of 6.5, this way your media will hold a solid 6.5

If you start with 6.5 and water with 8.0 you will be forever chasing your pH.

[rnewste]

Thanks Redcluster

Ray