Tomatoes need shade in AZ...not more water.

They will turn crispy critters on you by May even in the shade...that is why "they" advise growing small fruiting types here, ripens faster.

Plant tomato plants outside in mid-February...keep them covered with insect barrier cloth (20% light blocking) for shade and to keep sphinx moths/hornworms and keeps the local cactus wren out.

Once it hits 90-95 degrees, pollen is dead and tomatoes will not set fruit...right now is a good time to have flowers on tomatoes. Flick the flowers every morning to pollinate while under covers.

Good Luck!

I've been trying to grow larger tomatoes here for about the same length of time as you. I've had the same splitting problem. In previous years I didn't use mulch because I was green and didn't know any better. This year I'm using my dried leaves as mulch. I hope these help to maintain a good even moisture level not only around the plants but in between them as well. I'm going to mulch my cucumbers and peppers heavily as well. I believe my bitter cucumbers was caused by a lack of moisture control.

I've found out that smaller fruited is better. My large red cherry produced like crazy last year. This year I've got a Sweet 100, Roma an a couple of early girls. Hope to get a lot.

Good Luck!!!

There are numerous medium (4-8 oz.) short day (less than 70 day) tomatoes available from seed companies. You are not likely to find them at your local plant place. They sell only the most heavily advertised varieties. I plant 50-60 day tomatoes in March/April and a second crop in early September. I also have my raised beds covered with shade cloth over an 8 ft. canopy, works very well. I start my seeds indoors about 8 wks. before setting out. The days listed for tomatoes is determined from the transplant date.

You need to select tomato varieties that can tolerate the heat. Cherry tomatoes do well and they can handle the sun--not well but they'll handle it.

Give your tomatoes some shade and mulch, mulch, mulch. I plant Early Girl (indeterminate) and Celebrity (determinate). I plant these tomatoes under mesquite trees. These won't cover your burger bun but at least you can slice them.

I haven't tried Roma tomatoes or the little pear shaped ones in my own garden but a neighbor grew them last year and they tasted fine.

Heirloom and large fruited toms are a pain to grow here...so are paste types. Here are the tomato plants I had best luck in Chandler, AZ:

Aunt Ruby German Green....heirloom ripens green with streaks of red...cactus wren doesn't know to eat them because they never turn red. (I still cover them to keep the Sphinx moths out).

I grew a two pound tomato on this plant a few years back...I can't seem to locate the picture, though, I thought I had it on the WWW somewhere.

Red Chief...got seeds from a friend she saves them every year so it must be another heirloom OR open pollinated, at least. Not sure if one can even find these seeds for these tomatoes anywhere...see if you can trade on the tomato forums.

Heatwave....I buy plants from HD or Lowes every year....BEST TASTING tomato of the bunch they sell. Another friend says she grows them from seeds..but I can never find the seeds around.

I am trying out San Marzano this year...I am very hopeful for this tomato. So far: grows very fast and it seems to WANT it to get HOT...I still have it inside a "wall-o-water"/tomato teepee thing and it LOVES it.

Paste tomatoes are a big problem for me here in Chandler...they are very touchy about the heat and will get BER very quickly. I hope San Marzano changes that for me. :)

Blossom end rot is cause by one of two conditions. Lack of constant soil moist or lack of calcium availability in the soil not heat.

I do not know about NM since I have never grown a tomato there.

Here in Arizona...the air is so dry, the moisture in the soil is NOT enough to keep the tomato plant healthy...hence BER.

The roots CAN NOT get enough water up into the plant fast enough on DRY days to keep up with the moisture lost through transpiration via leaves. EVEN WORSE ON WINDY DAYS!!!

Hence...I keep plants covered and in the shade....there is less loss of moisture. This is much more important than "even watering". The roots will go DEEP seeking water in the soil...that is what I want here.

Well, here we are 1 year later, with no change in watering days or time or amount, and I have shade cloth up and running.

Plants look better than past, but the tomatoes are splitting again.

The Roma tomatoes seem to be fine, just the "regular" tomatoes are splitting.

Frustrating.

Okay, now that we have the sun issue solved, lets look at the soil. Describe your soil and any amendments you have added.

Raised bed, covered with mulch, use manure for fertilizer.

Okay, 1) what media/soil went into the raised bed (be as specific as possible), 2) what material is in the mulch, 3) is the manure fresh, composted, or store bought, 4) is the mulch and manure tilled/dug into the soil in the fall and 5) do you use any additional inorganic or organic fertilizers other than manure?

"garden soil" from somewhere went into it (4+ years ago), mixed it with a bit of top soil.

Mulch is hardwood... could not find any of the plastic stuff.

Manure is store bought, in bag

Manure is tiled into the soil in fall, and I apply as necessary on top of soil

Thanks for the help.

Your soil seems to be okay so let go to your watering schedule. In your OP you said the tomatoes were splitting. If you mean splitting of the skin then the problem is to much water at the end of the fruit's maximum growth. Picking the fruit when it begins to ripen and allowing it to continue ripening off the vine will not reduce the taste/flavor of the tomato. Doing this will eliminate the splitting problem. Timed watering is a real time saver but can lead to over watering and unnecessary expenses. Check the soil moisture by simply sticking your finger in the ground to a depth of 4-5 inches. If the soil feels cool/cold then don't water, if it feels warm, water deeply.

I have been wanting to comment on this post for awhile. First of all, while I do not believe that there is anything wrong with using shade on tomatoes, it is not required. I grow commerically and my question is have you even seen a field of tomatoes with shade screens set up? I think that they are several key factors here, some have been covered quite well. Yes you need to mulch, mulch, mulch around those tomatoes. I only water every two weeks and it forces the roots down, but it you check my soil under the mulch, it is damp. I think the other thing with the scalding of tomatoes and the drying up has a lot to do with the variety planted. If you plant a type with little foilege in this heat, those tomoatoes will suffer. So Ponderosa and some of the others with limited leaves out out in this sun. While I agree that growing earlier tomatoes is a safe move, we can, and do, grow beefstakes here. I say grow multiple varieties and find out what does best for you. Since I refuse to grow hybreds, I can tell you a nice tomato that is normally 8 ounces is the Rutgers that does well here. As far as the calcium shortage causing bloom end rot, I have heard the other side of this argument coming from Renowned Dr. Carol Male, and she says it is not the case. One thing she does say is that a lot of blossom end rot is that some varieties are more prone to this than others, and to switch to another type if this is the case. I tend to agree with her. No matter what you do, splitting of tomatoes is just part of living in this heat, but like it was said picking before a major watering can prevent some of this issue. Do not get me wrong I do put calcium in to my soil every year. I would say to the guy using manure, stay away from it as it has a tendency to have a lot of salt in it. This soil is alkali enough without adding more salt. Use leaves, grass, etcetera. There is a company out in Goodyear that sells an organic spray with 72 trace elements. You may wish to pick some of this up I belive it is called BioFlora. Since I am organic, I feel there are a lot things we need to stay away from.