Some new challenges have presented themselves over the past few days on the rooftop garden. Our heritage tomatoes are starting to ripen, and from above, seem to look great...
A closer look, however, reveals some problems...
Some of our rooftop tomatoes seem to be suffering from blossom end rot, a problem caused by calcium deficiency in the fruit. Sources I found explain that the deficiency is not always the result of low calcium levels in the soil, but more likely linked to erratic watering. Fluctuations in soil moisture levels reportedly reduce uptake and movement of calcium into the plant, resulting in tissue breakdown that leaves the dry, sunken lesions that you see in the tomatoes pictured above. Although we do our best to water regularly and thoroughly on the rooftop, it was especially difficult to maintain sufficient moisture levels in the containers during the heat wave we've just been through, leading me to believe that calcium uptake, rather than level of available calcium is a likely causal factor for the problems we're now seeing.
That said, however, it would be interesting to know what the calcium levels are looking like in the tomato pots, so I would like to do some soil testing at our next rooftop workparty and will report back with my results. pH could also be a contributing factor to the problem - tomatoes are able to absorb the most calcium at a soil pH of 6.5 - so we will look into this as well.
There is a lot to be learned from this experience! In an effory to improve our record keeping, we've created a new "Rooftop Garden Log Book" and labelled every pot on the roof wih a number. We hope to use this to build a document that tracks the successes and failures in our rooftop experiment, so that we can continue to improve our understanding of best practices for growing food in small spaces.
And, lucky for us foodies, these lesions are only skin deep. After cutting away the blemish, these are really a beautiful (and delicious) garden harvest!
Yum!
For more information on blossom end rot, try some of these sites:
