Mats,

Thank you for using the Ask Extension Service.

It is good to hear from you again. As I recall you have been growing your tomatoes in these 15 gallon pots for a few years now. Have you replaced the soil each year? It is important, especially with vegetables to replace the soil each growing season with a good quality potting/container mix. You can mix up your own soil as well. 

Have you fertilized your tomatoes? Did you use a starter fertilizer when transplanting your tomatoes? This can give a early boost to your tomatoes. You can then fertilize the tomatoes every four to six weeks until the fruit is 1" in diameter, then cut off the fertilizer. 

Most purchased pH meters are not as reliable as having a soil test done at a reputable lab. CSU Soil lab is now located at the Spur at the National Western complex. They do a full range of soil tests. If the pH in the one pot is truly 8.0 or higher then your tomatoes would not do well. It is too high for most vegetables and plants.

Continue to provide good watering and afternoon shade on these very hot days. If the temperature is 90 degrees by 10am the plants may drop their flowers or stop fruit production. You may want to keep the shade cloth on during the hottest days. This may be the best you can do for you tomatoes this season. 

If you have any additional question please reply to this email. 

Best,
Debbie M.
Arapahoe Master Gardener

Thank you Debbie!

I should have provided more background, sorry! The soil mix is new and the same as the previous 3 years, 2cubic foot  prepackaged container soil with 1 cubic foot composted cow manure. Both the economy version from the big box stores. I have to say that the soil seems to cake on the top a lot more than previous years. I added 1/4 cup of fertilizer when i transplanted the tomatoes and have been feeding them every week with liquid fertilizer, maintenance strength. I added a picture from 8am this morning where you can see that they are leggy and not very lush, even though they get a lot of sun. The picture is taken looking south. I changed my setup this year and instead of having the pots on top of the wall with a sun shade around the pots, I built the wall high enough so the tomatoes are shaded by the wall. The soil temperature at 10 am today was 77 degrees with an ambient temperature of 85 degrees.

I haven't considered providing more shade but per your comment above maybe I should.

I totally agree about the pH meter accuracy  but it is very convenient to do it yourself since precision isn't critical. I purchased buffer pH solution mixes and plan to calibrate the meter today for improved accuracy. 

Every year is a new learning opportunity and this year, my Brandywine tomatoes have yet to mature, almost a month behind last year but unlike some years, they don't show any sign of blossom end rot.  

 I realize that there's not much to do to improve the situation for this year. Any value of using fertilizer for acid loving plants?

Mats 

Hi Mats, 

Thank you for sending a picture of your tomatoes. I see the wall you built to help shade the pots. You can provide some additional afternoon shade as we discussed. The weather has been so hot it wouldn't hurt. 

I think you have been fertilizing your tomatoes too much. You should fertilize every 2-3 weeks and cut off the fertilizer when the fruit is about 1" in diameter. Nitrogen encourages foliar and plant growth resulting in longer, leggier plants. I am not sure if the heat has also contributed to leggier leggier but I have seen some of the tallest tomatoes this year, including in my garden. As you say, every year is different and a learning experience. 

This year tomatoes seem to be ripening later, again the heat may delay the ripening. If the temperature is 90 degrees by 10am the plant may drop flowers or fruit as a way to conserve energy. So I think we need to be patient. 

I think I would not mess with the soil or additional fertilizer products at this time. Just continue to provide adequate water and some shade on the hottest days. 

Debbie M. 

Thanks Debbie!

Many good things to think about. I will enhance my wall to provide more shade for the pots and figure out how to provide a movable shade for the foliage.

FYI, I compared my $50 pH meter readings against the buffer solution mixes I just received and the meter was spot on at 4.0 and 9,0 and a measured a little high on the 6.8 sample, With that knowledge, I tested the container potting soil I used for the tomatoes by itself and that came in at 6.8 but the "Mountain Country Composted Dairy Manure" came in at 8,5. In trying to wet it down in a pot for the test, I also discovered that the drainage is very, very poor and that this is the source of the soil surface caking, much to my surprise. I will obviously not use 1/3 of that in my mix, if at all, I also tested the Pro Mix peat based container soil that I plan to use and that also measured 6.8.

Thanks again for your help!

Mats

Mats,

Thank you for sharing your testing results. Good observations regaring the manure product that you had purchased. Sometimes these products to not have any amendments in there to help with drainage and pores for oxygen. 

Isn't gardening fun? We learn something each season that will help us the next season. 

Debbie M. 

Thanks Debbie!

Yes, every year is different and this week, another question for you. Unlike previous years, this year the squirrels are ravaging the tomatoes, especially this last week. Both the full size and the  cherry tomatoes are eaten. Is there a netting that will give the tomatoes the little shade we talked about and at the same time keeping the squirrels out? 

Mats

Mats,

Squirrels are a problem for sure. There are some sun shades that are rated by the amount of sun allowed through the material, e.g filters out 75% of sun rays. Sometimes you will see this sold as window screening and you can buy it by the roll. I am not sure if the squirrels would get chew through the mesh or if they would be deterred by the mesh. 

 Debbie M.