Garden Plant Families – Solanaceae – the Nightshades

Well, tomato season is FINALLY here (we’re late this year due to our cool spring), so I thought the next in the series on garden plant families should be Solanaceae – better known as the Nightshade family.

This is a continuation in the series on garden plant families. The first installment, on the Brassicas – aka mustards – aka crucifers, can be found here. The second installment, on mints, can be found here.

When we moved to Walla Walla from the high dry desert southwest of Colorado, where I had spent 10 years trying to eek out a handful of ripe tomatoes at almost 7,000 ft, my husband asked me, “What are you most looking forward to growing in your new climate?” To which I answered, “Tomatoes, tomatoes, tomatoes.” And that’s what I’ve been doing ever since. Nine glorious years of exploring the world of heirloom tomatoes.

Mortgage Lifter tomato, weighing in at over one pound.

But of course, the nightshade family includes more than just tomatoes. It also includes tomatillos (which I just learned are NOT self pollinating), ground cherries, potatoes, peppers, and eggplant. Interestingly, it also includes tobacco, petunia, and goji berry, which I had not realized until looking up information for this post!

The nightshades we eat, that have become such a staple in our diets, come from the new world. Tomatoes are native to western South America. Chili peppers come from southern Mexico and central America. Potatoes from southern Peru and northwestern Bolivia. Tobacco from the southwestern US, Mexico and all the way down into South America.

Old world nightshades often included plants that were either poisonous or mind altering (mandrake, belladonna, henbane), though there were new world species that had similar affects (datura). This was part of why it took a while for these food crops to be accepted by the doubtful Europeans. Though everyone seems to have taken to tobacco rather quickly (hello seriously addicting nicotine).

Note everything in sets of 5, the connected petals, and most distinctive, the stamens, which form a cone in the center of the flower, all but hiding the female part of the flower.

Solanaceae share the traits of alternate leaves, and flower parts in 5’s (five united sepals – the green part UNDER the petals, 5 united petals, 5 stamens – the pollen producing male part of the flower), and a two-celled ovary. Once you’ve looked closely at the flowers of a potato, chili or tomato, you pretty quickly learn to recognize this pattern. In fact, now that I realize that goji berry is a nightshade, its abundantly obvious to me from looking at the flowers.

Potato flower. Recognize the pattern here?

Due to their distinctive structure, many nightshades are thought to be self fertile. The pollen producing male parts cover the female pollen receiving parts, effectively preventing them from being pollinated from nearby plants by wind or insects.

That said, I recently saved seed from what I thought was a German Pink tomato, and ended up with a cherry tomato. I think that my German Pink crossed with a nearby sungold cherry tomato. Last year I was able to see a presentation by Joseph Lofthouse, who is working to return tomatoes back to their wild promiscuous selves by devolving them, thereby increasing their genetic diversity (which makes them more adaptable to a variety of growing conditions). He calls this Landrace Gardening. He searches for tomato varieties where the pistil (the female part of the flower) is not covered by the male parts. German pink tomatoes have larger, fluffier than normal flowers, and I suspect that’s how my cross happened. That and a really enthusiastic bee! Read more about Lofthouse’s experiments in landrace gardening by googling his name, or reading his pieces for Mother Earth News.

Last year, I saved seed from my accidental wild cherry cross and grew out the plants again this year. I’ve got one that is a yellow/orange stripped cherry and one that is a red cherry. There’s definitely some deep genetics hidden away in there!

There are people who have an allergy to the nightshades. I live in fear of this allergy, as tomatoes and chilies are my two very favorite things to grow. I’ve written extensively about my love of chilies and all of their uses, reminding people that a green chili is an unripe chili – always, and that paprika is just a specific type of chili. They are such a staple in our lives!

Eggplant, not so much. I’ve tried. I just don’t love it. Italian. Japanese. White. Doesn’t matter. Sure, if you bury it in cheese and breading and tomato sauce, its lovely, but most things would be. I’ll happily eat it when its served up, and I make a batch of moussaka every year that I freeze in individual servings for quick lunches. But eggplant is never gonna be a vegetable I get passionate about.

I quit growing eggplant for market when I realized that this wasn’t unique to me. I had a hard time selling them. That plus the fact that they don’t hold well, turning discolored and soft with only a few days in the refrigerator, made me give up growing this gorgeous vegetable in my own garden. I buy from fellow farmers when I need a few.

Potatoes, of course, are a staple around the world. They are incredibly nutritious if you don’t drown them in butter and sour cream. Chris Voigt, executive director of the Washington State Potato Commission at the time, ate nothing but potatoes for 2 months in 2010!

We grow a variety every year. I’m still in search of truly good information on potato varieties, whether they are early, mid or late maturing, and most importantly, how well they store. I’ve yet to find it. I’ve found that blue potatoes are always the first to sprout in my garage pantry, and I have problems with hollow heart in my red wax type potatoes. I always plant a bit too early and lose the new growth to a frost. But they always recover. And every year, we donate part of the crop to the gophers. But there is nothing like a pantry full of potatoes to make you feel rich as you head into winter.

As an aside, if there is ONE vegetable you should pay extra to buy organic, its potatoes. Back in another life, I covered the San Luis Valley in Colorado as part of my job. This area is fascinating geologically, culturally and biologically, and it is famous for growing seed potatoes, i.e the potatoes you order to start your own potatoes in the spring. (You CAN grow potatoes from true seed – but it takes a while, and what you get is a roll of the dice. Google for details).

Potatoes are notorious for picking up viruses and other diseases as they grow. And because you don’t start them from seed, but rather from last year’s crop, those diseases tend to proliferate and build up in the plants and soil over time (which is why they tell you to buy expensive “seed” potatoes each year rather than simply planting part of your own previous year’s crop).

The San Luis Valley is ideal for growing seed potatoes. And they are irrigated with center pivots, a watering system where a very large sprinker rotates in a circle from a central point. A center pivot is typically 1/4 mile long and irrigates about 130 acres at a time.

San Luis Valley Colorado, via Google Map satellite. About 35 miles across. Land of the center pivot. Note not EVERY circle you see is a potato circle!

When a center pivot breaks during the potato growing season in the San Luis Valley, they will let the entire circle die and collect the insurance on the crop (a value of up to $250,000!), rather than go out into the field and fix the pivot. Because the crop is SO TOXIC when its growing that its an extreme hazard to humans. Michael Pollman’s book Omnivore’s Dilemma also talks about this insanity. The potatoes themselves only become less toxic over time due to size (ie the pesticides they contain become more diluted as they grow larger). So, buy organic potatoes, or grow your own!

I highly recommend Carol Deppe’s book The Resilient Gardener for more on growing potatoes as a stockpile against grocery store uncertainty. She has a whole section dedicated to potatoes.

All the nightshades we eat are warm season plants. That means they die when exposed to temperatures below freezing. They also really like warm soils, which means that even if you direct seed after the danger of frost has passed, they will either not germinate, or grow very slowly until your soil temperatures reach 60 degrees. And they can take a long time to mature, often well over 100 days from seed to ripe fruit in most instances. That means that, with the exception of potatoes, most nightshade plants are started up to 8 weeks before your last frost date in a greenhouse or other protected place in order to give them a head start.

Around here, our last frost date is in early May. That means that I start my tomatoes and peppers from seed in early March (8 weeks before last frost date). Note: I do NOT start them in late January or February. That just gives me plants that are too big and often leggy and fragile before they can be safely planted out. I’ve learned that lesson too many times. Avoid getting overly ambitious in the very early spring. It doesn’t buy you anything.

I plant out around Mother’s Day. And often, the soil isn’t really all that warm, and so the plants just sit and give me the finger, getting battered by wind and rain and not actively growing, for about the first two weeks. Eventually they take off. Peppers are even slower.

I grow primarily heirloom tomatoes, and use homemade 6 feet tall concrete reinforcing wire cages to keep them contained. The cages are kind of expensive to make, but they last for years, and don’t fall over when the plant gets over 6 ft tall! I plant a total of about 35 tomato plants each year, trying a few new varieties each time. For the most part, I do not prune. My current favorites for flavor, and not cracking on the vine or on the way to a market, are German Pink, Stripped German, Valencia, Cherokee Purple, Mortgage Lifter, Kanner Hoell, Brandywine and San Marzano Redorta. Your mileage may vary. Climate factors in. A LOT.

Tomatoes and peppers really enjoy heat. Every year, people locally plant their tomatoes and expect ripe fruit by the forth of July. Every year we don’t really start seeing large production until early August. And this year, they are especially late. There is a way to track this called Growing Degree Days (GDD). GDD is defined as the mean daily temperature (average of daily maximum and minimum temperatures) above a certain threshold base temperature accumulated on a daily basis over a period of time. 50 degrees is normally the threshold. Degree days are cumulative, and each degree over the threshold counts. So, if the average daily temperature is 60, that day is counted as 10 (ie 10 degrees over the threshold). If the following day average is 65, you add 15 to your 10, and now you have 25 GDD. Google to find GDD calculators. I don’t have a favorite.

Heirloom Bull Nose bell pepper, dating back to Thomas Jefferson’s garden at Monticello. I grow them every year.

On July 24th, I compared our GDD this year and last year. This year, 1170. Last year (which was ideal tomato growing conditions – the best season I’ve seen in the 9 years I’ve been growing here), 1582! There is a strong correlation between GDD and soil temperature. And a strong correlation between soil temperature and tomato maturity. In short, our tomatoes are not ripening nearly as fast this year as they did last year. Because its been a cooler year.

As climate continues to become more volatile, GDD may become the benchmark by which farmers plant, rather than old adages like, “plant your tomatoes on mother’s day” or “plant when the snow is off the mountain”. Large commercial crops already track this both for planting and for pest control. Oregon State University is working on making this information crop specific for smaller vegetable farmers. More information on their “croptime” scheduler here.

Why do we care about all of these “plant family” connections? Partially due to disease and pest issues. Diseases and insects that affect tomatoes tend to also affect peppers or eggplant. This is why its often recommended to rotate your garden crops each year, so that diseases specific to certain plant families don’t build up in the soil over time. I rotate all of my nightshade family plants each year, though given that 1/3 of my entire garden is tomatoes, peppers and potatoes, it takes careful planting to make sure I’m not overlapping from year to year.

Thankfully, the only real nightshade “pest” I have to deal with is stink bugs. These bugs stick their straw-like mouthparts into the developing fruit, leaving behind mealy white spots as the fruit matures. The damage is unsightly but shallow and easily cut away. I mostly see it on my tomatoes. Thankfully, its not a huge issue for me. I just keep the damaged fruit for my own use, rather than having to spray my tomato jungle. My giant row of sunflowers helps attract lots of birds to the garden, who then help me with bug patrol.

Nicotina volunteer in my corn last year. Nicotina tends to bloom in the evening, filling the air with its wonderful scent.

If I could only grow one plant family in my garden, the nightshades would be it! So many of my products (and some of my very favorites) are based on them. And so many of my recipes feature them. All hail the nightshades!