Cassandra is the variety of lettuce pictured above and it is described as follows:
"A superb quality, pale green butterhead of excellent flavour, with well-filled voluminous hearts. Lettuce Cassandra is resistant to most races of downy mildew and Lettuce Mosaic Virus. Ideal for growing all year round, especially summer and autumn outdoors. Harvest: 10-12 weeks from sowing. Very easy to grow."
I found it to be all of the above, except it does have a slight tendency toward tip burn. As my test grow only took 6 weeks from seed start to salad, the tip burn may be associated with the rapid growth and calcium not getting to the tips. In our opinion, the tender butter colored interiors of the heads make it well worth growing.
Six plants were placed in a modified aeroponic unit on 11/8/2010 using a 90 watt red/blue LED with a photoperiod of 16 hours, and in less than four full weeks the plants were ready to harvest.
Out of curiosity I asked my wife to price specialty lettuce at the local market, and when she returned she said that specialty lettuce was being sold for $3.99 for 5 ounces. After trimming, the above plant yielded 7.5 ounces, or to put it another way, the market value of the produce was $5.98. As there are six pots in the system, the value of the harvest is in excess of $35.00.
To continue the economic evaluation; I estimate the cost to run the LED for four weeks at about $3.00. The nutrients and seeds I estimate at well under a dollar, so we have $31.00 in produce for basically nothing but a little effort.
The book I am reading says that commercial growers may use as many as six different pesticides when growing lettuce. Consider that the EPA has deemed each of them as being safe. Then, consider that the EPA has no idea of the synergistic effect of these six chemicals on your body.
I have to believe our little effort is being rewarded, both economically, and in terms of our health.