When to plant heirloom tomatoes:Phenology and planting time of fruits & vegetables in a Northern Garden

Grandpa and Tesla
Grandpa and Tesla

Cris and I used to get quite a laugh out of his dear father, a salt of the earth man who loved to garden, fish and provide high humor for his grandchildren.  He was a man of strong beliefs, especially about his garden.  Potatoes must be planted on Good Friday; trees must be pruned on Presidents Day; and never plant anything during the full moon.

Before starting our small farming adventure in Minnesota, I went to a number of classes, seminars and  basically anything I could find on organic farming.  I learned a great deal about soil, cover crops, organic disease control, etc.  One of the seminars that was especially intriguing however, was a scientific lecture on Phenology.  I had never heard of it before, and I couldn’t believe it when I heard some of Willis Stainbrook’s folklore being espoused as a truth based on science and history.  Not the holiday planting lore, but some of the little things he used to do.  I’m sure if he was still with us and someone told him his knowledge was scientifically sound, he would respond “Pwiffwah,  everybody knows that.”

The National Gardening Association has this to say about Phenology:

Phenology has been used for ages in gardening and agriculture to determine when to plant, when pest insects will become a problem, and when plants will bloom. It turns out there is scientific basis for these observations. Modern plant scientists have found that phenology corresponds to a measurement called growing degree days. Growing degree days are calculated by adding the average daily temperature to, or subtracting it from, 50°F. This information provides a way to estimate the timing of certain events, such as when controls for pest insects need to be used to maximize their benefit.”

Spring Bed Ready for Tomatoes
Spring Bed Ready for Tomatoes

With respect to tomatoes (especially heirloom tomatoes)  a fairly specific rule of thumb in central Minnesota is to wait until memorial day to plant.  I do follow this rule to great success, but understand that my heirloom tomato seedlings  have been potted up into 4″ pots and have been fully hardened off, not little wispy things and not big honking plants that have already spent their energy coming to bloom.

Every time I have been fooled into planting early by a warm spring, a cold spell has followed and the plants are either stunted or they just sit there in the ground waiting patiently, but not growing.  The tomatoes planted on memorial day always catch up with any progress the early plants have made.

Here’s some other phenological pieces of planting wisdom that I picked up from that class or along the way: Continue reading “When to plant heirloom tomatoes:Phenology and planting time of fruits & vegetables in a Northern Garden”

Using Sun-Dried and Smoked Heirloom Tomatoes in Winter Recipes: Skillet Pizza

Last year I grew a lot of Principe Borghese tomatoes for drying and they are the best, bar none, for making sun-dried tomatoes (or oven-dried).  I sold most of them at the St. Paul Farmers’ market in the fall, but I managed to keep enough for me to cook with this winter.  They add the most intense tomato flavor to any tomato-based dish you may be making, and they are really easy to use.  Just soak them for about 20 minutes in warm water, drain, dry and they’re ready for cooking (and keep the drained tomato water for other uses, like tomato martinis).

The reason the Principe Borghese variety of heirloom tomato is so wonderful for drying is two-fold:

  • the flavor is an intense classic acid tomato flavor that you get with larger globe tomatoes.  It is not the sweet or mild cherry tomato flavor, which is wonderful for eating out of hand and in salads but not intense enough for cooking with in my opinion.
  • they are the perfect size for drying, and they are meaty rather than juicy.  You can just cut them in half, place them on the drying rack and they dry quickly, keeping their bright color.

If you want step by step on how to dry your own, see this post at thefarmtojar blog.

I also tried smoking tomatoes last fall and have been using them together with the dried tomatoes for some really outstanding flavorable dishes.  I haven’t got the whole smoking thing down yet, but I’ll be concentrating on that process with this year’s crop.  Last August I used all different varieties of heirlooms and smoked them with an outdoor smoker on my deck.  While the flavor of these smoked tomatoes is great, they were more much more difficult than the Principe Borghese to store, due to the juiciness of the fruit making them pretty soft after smoking.   I ended up putting them in a ziplock and freezing them.  After talking to some farmers at the Ferry Building Farmers’ market in San Francisco this January, I realize that next year  I am going to have to dry them in the food drier, as well as giving them time in the smoker.  Now the debatable question seems to be:  Should I dry them slightly BEFORE smoking, or should I smoke them first and then finish them by drying them off?

I’m going to write to my favorite guru on all things regarding science and cooking, Dave Arnold at Cookingissues.com.  He has a really interesting podcast every Tuesday on Heritage Radio that I listen to without fail.  He’s kind of the irreverent Harold McGee of the podcast world.  I love so many of the food podcasts and have learned so much from these people that are sharing their expertise for free on itunes. I’ll let you know what he says regarding smoking tomatoes.

One of the first things I tried this winter with the smoked and dried tomatoes is a pizza.


I used the pizza dough recipe from Cooks Illustrated because a) it was quick, b) I like the idea of using a little beer to get the yeast taste, and c) there is nothing wrong with having a half bottle of brown ale left over to drink with the pizza.  It made a really nice crisp, tasty dough…almost like a flatbread.  I can’t post the dough recipe, as Cooks Illustrated does not appreciate sharing their recipes online, but it is from this issue:  Cooks Country, August/September, 2008.  You can find several renditions of skillet pizza dough online. Basically this dough requires some flour, a little sugar, a little salt, and some baking powder in a food processor, with some NewCastle Brown Ale added while the processor is on.


My recipe for the Sun-Dried Skillet Pizza:

9″ round of thin pizza dough (see above)

1  cup sun-dried tomatoes

1/2 cup smoked tomatoes

3 Tbsp. olive oil

4 oz. buffalo mozzarella cheese, torn into 1″ pieces

2 cloves garlic, finley minced

1/4 cup green scallions, chopped



  1. Soak the tomatoes in warm water to cover for about 20 minutes while you are making the dough.  Drain the tomatoes, reserving the tomato water for later uses.  Dry the tomatoes a little with a paper towel.
  2. Heat 3 Tbsp olive oil in a large cast iron skillet until just smoking
  3. Place the rolled-out dough round in the skillet and cook over med heat for about 3 minutes.  While it is cooking, poke the bubbles that form with the tines of a fork to release the air and keep the dough flat.
  4. When the bottom of the dough begins to crisp and brown (about 3 min.), use a pair of tongs to turn the dough over in the skillet
  5. Place the tomatoes on top of the dough and the mozzarella on top of the tomatoes.  Sprinkle with the garlic and the scallions.
  6. Cover the skillet and turn the heat to med-low.  Cook covered about 5 minutes, or until the cheese has melted.


I loved the intensity of the tomatoes on this pizza.  I plan on trying it with other dough recipes also, but it was just right with this thin, crispy crust.