the watering depends more on the soil and drainage than whether they are "heirloom".

If the soil was dug well and you don't have excessively high temps and high winds then you could water each spot for about 4-6 hours once a week. What this encourages is the roots to chase the water into deeper soil. When they can do so the plants will be better off because the majority of roots when be in deeper soil where the moisture fluctuates less.

If you water short intervals but more often, the roots stay near the surface. In that situation they are more susceptible to stress from fluctuating moisture levels and the problems that go with that kind of stress (like blossom end rot).

Be sure to mulch to help conserve moisture.

Agree with Mulio. Heirlooms has nothing to do with it. Raised beds - if I understand your info correctly - will dry out more quickly than in-ground beds so closer monitoring of the soil moisture level is required. That means digging down by hand, sticking your finger deep into the soil to check it on a frequent basis before you water.

Right now it sounds like you are watering too frequently and too shallowly. MUCH deeper and less frequent watering is much better for plants for the reasons Mulio already mentioned.

Plus the roots don't hang right around the stem, they spread out for several feet. So 1 dripper at the stem base isn't sufficient. Depending on spacing you may need an additional 2-3 drippers between plants.

A trick to setting up a drip system - take an empty soup can and bury it in the soil so the top rim sits right at the top of the soil, put a dripper over it, run your system and see how long it takes to fill the can. That is approximately how long you need to run your system 1x a week. If the weather is especially hot, if your plants are not well mulched, or if your soil drains quickly it will be more often. If it rains adjust accordingly. As the plants grow and set fruit increase accordingly.

Hope this helps.

Dave

I just set up drip irrigation this spring for my entire garden, but WOW has it made a huge difference for my tomatoes! They are more flavorful and much larger/prettier than I have ever grown. I have both heirlooms and some hybrids like Park's Whopper and they all seem equally healthy.

I burried 1 GPH drippers about a foot below each plant. I have the timer set for 20 minutes every 12 hours (6 AM and 6 PM) so they get a little over a half gallon of water every day. It is VERY HOT here-- 100+ every day and I have sandy loam soil that is well mulched. Much to my surprise, they are all still blooming and setting fruit. I couldn't be happier with my system--well worth the time and effort to set it up!!!

I have my Toms in a 10' x 3' raised bed also. I used to water with a full drip system (3 emitters to each plant...took a while to get set up every year). A couple years back I took all the drip emitter out, and replaced them with adjustable micro sprayers...4 per bed. I have them on a timer so they get watered 20 minutes, twice a day (7am and 6pm), every third day. The bed is about 24" deep, well dug, top dressed yearly with compost at the end of the season (we have horses). The bed never fully dries out, but the top 3-4" does get dry. Below that 3-4" it is cool and moist, not wet. I crushed one of my cages last year under an Early Girl Tom. Each year since converting, when cleaning the bed out the root systems of the plants are nothing short of amazing. Roots as big as my little finger, many run the full length of the bed, growing the full depth of the bed, and beyond (I have 1/4" steel mesh in the bottom to keep the burrowing critters out, the roots grow through it). I will get some slight wilting in the worst heat (not uncommon to hit 105+ in the summer months..for days at a time).

Anyhow, microsprayers. Much easier to adjust, much easer to place.

Hello all, thanks for your comments.

In my case, although I have single dripper, it drips 5gph about 2" below the soil right at the stem. Note that when I planted these tomatoes, these were 1/2 gal buckets with potting mix, which is very porous. putting water into stem directly gets absorbed into the potting mix that is 6" deep and surrounds the stem and roots. entire plant was burried about 8 inches below the top of soil and the I added about 4" of manure and garden soil to retain moisture.

I am hesistant to water too much but water is getting all the way down into deep roots and soil beneth. As planters are raised about 18"-24" above ground and then I burried the tomatoes about 12" below the top of planter, I think conditions allow for good drainage and at the same time retain moisture. I will let you know how it fares in days to come. I like what I see though.

I would also mulch heavily. Helps conserve the water.

OK, did some testing of soil moisture, went all the way doen 6-8" and found good moisture but not saturation. top 3" of soils is mostly garden soil and manure and it was pretty dry. I watered pretty well yesterday and will take a look at it again today.

That's what you need to do! Monitor the soil and then
make adjustments as needed.

I'm in SoCal like you, so I understand your worries about
our weather and your plants. I'm the same way.

I mulch with my grass clippings which helps considerably.
I know if the dirt under the mulch is not damp, it's time
to water. I know my garden soil quite well, so when the
top is just damp, the lower parts are probably quite nicely
moist. But still time water. In hot, dry SoCal, it takes
quite a bit of water to keep tomatoes happy and productive.

So keep up the monitoring of the soil, try to anticipate
any extra needs due to upcoming weather, and a dozen or
so other things.

Keep us up to date. I'm always happy to hear the experiences
of SoCal growers.

tomato plants are flourishing well, I put in 5' stakes for supports every other plant and plan on using jute twine to create a web/netting for support.

One worry I got now is that my system irrigates tomatoes and 5 other planters that have Peppers, Green Beans, bell peppers, and spanich. Peppers dont seem happy with the amoung of water being received and if I cut down or control water it may hurt tomatoes. I need to figure out a way to slow down water into peppers, etc. may be I will add a control valve there. Right now I got drips for tomatoes 4 gal/hr and for peppers I got 2 gal/hr. I water them for 12 minutes, three times a week. weather is hitting 90's already. wondering if 4 gal/hr for 12 min = 0.8 gal * 3 = 2.4 gal/week is enough water for these heirloom tomatoes. I will post pictures of the setup soon.