Planting Out Too Early -or- Neglecting to Up-pot?

This season’s crop of tomatoes is not looking quite as vigorous and healthy as last year’s crop – why?

Here’s what they looked like last year, in June of 2010, a little over one month after planting out:

and here’s what they looked like this year in June, about 1 1/2 months after planting out (2011):

The 2011 crop looks stunted, not as green and lush, and rather sad compared to the 2010 crop.

So what was different between the two crops?

1. Soil

   • same soil; bought in 2009 from same source
   • 2010 crop was preceded by corn and squash; 2011 crop was preceded by chile peppers

2. Amendments

   • cover crop: used clover as the cover crop both years; however, the 2011 clover crop wasn’t as successful
   • this could point to an issue with the soil, or it could have directly resulted in lower nitrogen levels available to the 2011 crop

3. Site

   • same relative area in the garden, just a few feet east of the 2010 bed
   • maybe a little less shelter from the sun as the 2010 bed

4. Weather

   • spring 2011 was perfect for the tomatoes: very moderate temperatures with a good dose of rain – very similar to 2010 spring
   • 2011 temperatures have stayed a little lower than normal, with a bit higher humidity, which the tomatoes should be loving

5. Water

   • 2010 rainfall was about equal to 2011 rainfall, up to April, but May & June got hammered with 6.8 inches in 2011, so the 2011 crop was getting way more water from planting to picture time
   • irrigation: the 2010 crop didn’t need any irrigation until late in June; the 2011 crop irrigation was turned on in late May

6. Seedling Care

   • most (3/4) of the 2010 tomatoes were up-potted twice before planting out: first into 2″ pots, then into 1-gal pots (I ran out of soil and got lazy, so the last 1/4 weren’t up-potted into 1-gal)

   • 2011 tomatoes, by contrast, were only up-potted into the 2″ pots.

7. Planting Out

   • 2010 tomatoes were planted in the second week of May; 2011 tomatoes were planted 3 weeks earlier
   • although it was 1 week after our last frost date, 2011 tomatoes got some very cold temperatures in the first two weeks they were in the ground (one night was 33.5°F, several were below 40°F)
   • temperature guidelines for tomatoes vary from source to source, with the minimum ranging from 45 to 54 degrees – one source goes even further to say to wait 2-4 weeks after last frost

The Verdict

Cool temperatures are known to stunt tomato plants, when they are just developing; since the 2011 tomatoes were treated to almost 3 weeks of temperatures below 54 degrees, this seems the most likely culprit.

Since I still want the tomatoes in the ground in April, I will need to use wall-o-waters or plastic mulch to warm the ground.

Update:

After pulling out 2012 crops from the bed that the 2011 tomatoes were planted, we found that the entire bed was heavily infiltrated with roots from our neighboring pine trees. Although these pine trees are probably 60 feet away, they were thirsty and found our lush, irrigated garden soil. We double-dug the entire bed, cutting out the roots with the shovel head. It was hard work – and work that will need to be done probably every year, or maybe every other year.

I still think the cool temperatures played a big role, but the top of the bed, where the pine roots were at their worst, performed even less well than the lower tomato plants.