I'm not sure how we did it during a hot and Sahara-dry summer that killed a lot of gardens hereabouts, but Mary gives credit to a deep bed of compost that contains the remains of most of our non-meat kitchen scraps for the last 15 years. The roots went so deep and the soil was so nutritious that the plants apparently fought off all attacks.
I wish now that I had kept count of the totals from our four San Marzano plants, four Italian heirloom oxhearts and two "brandyboy" beefsteak hybrids, but it had to be in the hundreds. We've been eating them on everything, and must have two dozen one-meal containers of fresh tomato sauce taking up a lot of space in our side-by-side freezer. I'll be very glad to have them to thaw and use on pasta in January and February, though.
