Question
QUESTION: Hi Elyse

Just wondering how to water tomatoes when the weather's schizophrenic - we had at least 3 weeks of no rain and constant temperatures above 85 degrees.  Suddenly it's showering intermittedly and the temp has dropped to 65 degrees and below at night, soon to warm up again.

The thing is, i've been steadily watering every morning because of the heat.  Now with rain falling sporadically and cooler temps, I don't know when and how much to water anymore; the plants are obviously not drying out as fast (or predictably) when it was hot, but I don't know exactly how far down the moisture from the rain is either!  Is erring on the side of caution in having the soil too wet a better option than letting it dry out?  

thanks

ANSWER: Watering tomatoes can be tricky, especially if your soil is slightly acidic. They shouldn't be allowed to completely dry out, sporadic watering can cause blossom end rot. On the other hand, overwatering as the fruits are ripening can cause cracking. Figure they need about an inch of water per WEEK. So daily watering is probably not necessary. You should be watering deeply, once or twice a week as opposed to shallowly more often. So now that it is raining off and on and cool, my guess is they will not need any water for a while. Also, once the tomatoes start to ripen I pull back on watering to almost nothing, depending on the weather and how late it is in the season. I don't know how long your season is there, so it may be too soon to be thinking about that.

Elyse

---------- FOLLOW-UP ----------

QUESTION: Thanks Elyse; I'm surprised you mentioned not watering every day when it's hot though? What if the tomatoes are all in plastic containers? They LOOK dry by the end of the day (at least, the top soil is and when I stick my finger in, at least 1 inch is dry).

It's late-spring where I am - so far, only one plant has a whole truss of tomatoes (green); the others haven't started doing anything yet; I keep getting blossom-drop from the looks of it.

Answer
Sorry, I forgot that you were growing in containers. Yes, you are right to water daily in that case. Continue testing the moisture as you have been doing. Blossoms will drop if the daytime temps are too high, they should start up again now that it is a bit cooler. Tomatoes are really temperature sensitive - one year no one I knew was able to grow a decent crop, with high temps during the day and below 50 every night.

Elyse