The Mercuri Winter Keeper Tomato is a rare and worthwhile variety of heirloom tomato that produces fruit with outstanding storage characteristics. The flavor can’t compete with a summer tomato, but we’re less picky in December, January, February, and sometimes beyond.
We acquired the seed through the family of one of Eric’s college friends, and we offer seeds through Seed Savers Exchange. Here’s the listing that we wrote for the Seed Savers Exchange Yearbook:
indet., potato leaf, winter-keeping variety, disease-resistant plants yield abundant golf-ball size yellow-orange fruits, store easily to December, an occasional tomato has persisted until the following summer, will ripen in storage if picked green; traditionally stored by hanging clusters of tomatoes, though side-by-side storage of individual fruits on shelves works well; preserved by Italian immigrant communities in Toronto, Ontario, seeds passed from renée I.A. mercuri; grown in Missouri since 2006
Members of the Seed Savers Exchange can request seeds from us for a small fee. We’re pleased that other members who have requested seed have liked the tomato enough to also offer seed that they’ve grown though the Yearbook, thus helping to make this wonderful tomato more available to others.
Planting date: Getting the planting date right can be a little tricky, as the goal is to have a big pulse of tomatoes ripening before frost, but not too long before frost (because that just means a longer storage time until they’ll be eaten). Relatively mature green tomatoes will ripen (but we’ve had more trouble saving seeds from tomatoes picked green). For the moment, we’ve settled on starting the seeds in late April/early May, followed by transplanting in early to mid June.
Growing: The plants are robust, and they’ve stood up well to some extreme insults. We often relegate them to less desirable growing areas, both to isolate them from other tomatoes for seed saving purposes, and because we know they can handle rougher conditions than most plants. One year, a bout of inattentiveness (that we attribute to a family visit) meant the plants were almost entirely defoliated by hordes of hornworms. Impressively, the plants managed to recuperate enough to still yield tomatoes by frost.
Harvest: We start harvesting when a meaningful number of fruits have turned yellow/orange. Our current preferred method is to lay these out side by side on plastic shelving with holes (to encourage air circulation) in a part of the house that stays cool-ish (50ºFs-60ºFs). If we can’t get to this task immediately, we’ll temporarily store them in a bin that has holes to allow air circulation; a solid container is just asking for mold & rot. We harvest periodically leading up to frost, and when a killing frost is looming, we’ll take (more or less) everything remaining, green or ripe.
In the kitchen: We’ve developed a liking for green Mercuri tomatoes over other green tomatoes; we think their firmness and tartness results in especially delicious fried green tomatoes. Ripe tomatoes can certainly be eaten on salads and such for those who want “fresh” winter tomatoes. We often prefer roasting them for a nice sauce.