Last year was a BER learning experience for me at the PS 102 garden.
There was a high incidence of BER that was puzzling because the tomatoes were growing in highly efficient sub-irrigated planters (SIPs) made from utility buckets.
A bit of web research revealed the cause which was "water starvation" that was due to lack of access to the garden on weekends. There were at least two incidences where the plants went into wilt. I am convinced it was the direct cause of the BER problem.
Lesson learned! I will never again donate time and materials to a school garden project without the full and complete support of the school principal. Seven day a week access is critical to the success of a school garden along with direct involvement by the principal.
After a story of mine about too-early planting of tomatoes appeared in the Chicago Tribune, a newbie gardener who had suffered a lot of blossom end rot in her first year of container tomato growing asked me how she could avoid it this year.
Here's what I told her:Blossom end rot in container tomatoes is usually related to watering, which affects the plants' ability to take up calcium.
Most good-quality commercial potting mixes have sufficient calcium. If you want to be extra sure, mix a handful of bone meal (which is about 15 percent usable calcium) or 1 tablespoon of dolomitic limestone in the potting mix before you plant. Mix it in well with all the soil in the container before planting and don't use too much.Soil pH also affects the plants' ability to take up calcium, but again, a good-quality potting mix should have a reasonable pH range. So don't sweat that.
It is much more likely that the rot comes from over- or under-watering. Tomatoes need a steady, even supply of moisture, not swinging from wet to dry and back again. If you are using self-watering containers, make sure that the reservoir has an overflow that is not clogged so that surplus water can drain away.
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1 Tablespoon of dolomite is not enough. Earthbox leadership recommends 1 lb per box - that's roughly 1 cup per cubic foot of potting mix. This will not immediately upset the pH as dolomite breaks down over time. Dolomite supplies both calcium & magnesium. To provide more calcium quickly, use a solution of calcium nitrate, per the Texas A&M extension website. http://aggie-horticulture.tamu.edu/publications/tomatoproblemsolver/green/end_rot.html
Posted by: dtj | May 24, 2010 at 12:31 PM