A recent addition to the line of zebra tomatoes. Bred by Jeff Dawson ‘Black Zebra’ is a natural and stabilised heirloom cross between a black tomato and Green Zebra, and its size and shape are akin to Green Zebra.
This purple/mahogany tomato has vertical deep green streaks, like brush strokes on the outside and solid mahogany-coloured flesh inside.
Black Zebra has exceptionally rich, complex, delightful tomato flavours that contain hints of smoke and sweetness which carries the rich complexity associated with the best of black tomatoes.
The regular-leaf tomato plants produce an abundance of perfectly round 4 to 5 cm (1½ to 2in) fruit each weighing around 85 to 110 grams (3 to 4oz). A vigorous and prolific producer with good disease resistance and drought tolerance.
Grow them in the conservatory or greenhouse, or grow outdoors in full sun in moist humus rich soil. They are also suitable to be grown in a container on a warm patio.
Indeterminate 75 days.
As they cannot tolerate any degree of frost the timing for sowing and planting outside is key to successfully growing tomatoes. Where the seeds are sown under cover or indoors, aim to sow the seeds so that they reach the stage to be transplanted outside three weeks after the last frost date. Tomato plants take roughly seven weeks from sowing to reach the transplanting stage. For example, if your last frost date is early May, the seeds should be planted in early April to allow transplanting at the end of May.
Tomatoes require a full sun position. Two or three weeks before planting, dig the soil over and incorporate as much organic matter as possible.
The best soil used for containers is half potting compost and half a soil-based type loam: this gives some weight to the soil.
Plant about 3mm (1/8in) deep, in small pots using seed starting compost. Water lightly and keep consistently moist until germination occurs. Tomato seeds usually germinate within 5 to 10 days when kept in the optimum temperature range of 21 to 27°C (70 to 80°F). As soon as they emerge, place them in a location that receives a lot of light and a cooler temperature (60 to 70°F); a south-facing window should work.
When the plants develop their first true leaves, and before they become root bound, they should be transplanted into larger into 20cm (4in) pots. Young plants are very tender and susceptible to frost damage, as well as sunburn. I protect my young plants by placing a large plastic milk jug, with the bottom removed, to form a miniature greenhouse.
Depending on the components of your compost, you may need to begin fertilising. If you do fertilise, do it very, very sparingly with a weak dilution. Transplant into their final positions when they are about 15cm (6in) high. Two to three weeks prior to this, the plants should be hardened off.
Just before transplanting the tomato plants to their final position drive a strong stake into the ground 5cm (2in) from the planting position. The stake should be at least 30cm (1ft) deep in the ground and 1.2m (4ft) above ground level - the further into the ground the better the support. As the plant grows, tie in the main stem to the support stake - check previous ties to ensure that they do not cut into the stem as the plant grows. Dig a hole 45cm (18in) apart in the bed to the same depth as the pot and water if conditions are at all dry. Ease the plant out of the pot, keeping the root ball as undisturbed as far as possible. Place it in the hole and fill around the plant with soil. The soil should be a little higher than it was in the pot. Loosely tie the plant's stem to the support stake using soft garden twine –allow some slack for future growth.
A constant supply of moisture is essential, dry periods significantly increase the risk of the fruit splitting. Feed with a liquid tomato fertiliser (high in potash) starting when the first fruits start to form, and every two or three weeks up to the end of August. In September, feed with a general fertiliser (higher in nitrogen) in order to help the plant support it's foliage. Over watering may help to produce larger fruit, but flavour may be reduced. Additionally, splitting and cracking can result from uneven and excessive watering.
When the first fruits begin to form, pinch out the side shoots between the main stem. Also remove lower leaves which show any signs of yellowing to avoid infection.
Pick as soon as the fruits are ripe, this also encourages the production of more fruit. Harvest all the fruit as soon as frost threatens and ripen on a window sill.
"An old heirloom variety," one seed catalogue says. "Origin: Unknown," says another. Actually, the originator of the Green Zebra was Tom Wagner of Everett, Washington, USA, a man obsessed with producing ever-better varieties of tomatoes and potatoes, whose bookcase holds binders with some 50 years of careful notes on hybridisation and disease resistance, and whose bathtub is full of potatoes.
Wagner's name is surprisingly little-known in the broader food-loving community. To those in the know, though, he's a legend. He is one of the most prolific breeders of potatoes and tomatoes who have ever lived, he has created so many potato treasures and his tomatoes are mind-expanding.
Wagner's work began early, with his childhood on a Kansas farm where his large, extended family depended for food on what they could grow, butcher, can or freeze.
From the age of 3, "I was interested in everything. I was breeding 50 different kinds of chickens," he said. Hospitalized for an operation at 12, he passed the time by reading the field notes of plant-breeding pioneer Luther Burbank.
Wagner majored in botany, anthropology and geology at the University of Kansas, doing the research for his degree on potatoes ("Got an A on it, obviously"). He was a potato buyer for Frito-Lay. He consulted for commercial growers and was certified as a substitute teacher.
The quest for the Green Zebra, with its characteristic stripes, began in the 1950s with Wagner's disappointment in a big green Kansas tomato that cracked and bruised practically before it reached the kitchen. He set out to retain the colour and eliminate the flaws. It took years and digressions and cross after cross, but he finally wound up with the strikingly striped final version, beautiful on the outside, piquant within. "Eureka!"
The Zebra's fame spread in part due to Alice Waters of Chez Panisse, in California who listed it as one of her favourites.
Wagner has other notables like the elongated, zigzagged Casady's Folly, or the globe-shaped Green Grape. But he's never attempted to license them preferring to leave them in the public domain. He has been incredibly generous, allowing interested gardeners and amateurs to take these and run with them.
And at age 65, Wagner hasn't slowed down. "To me," he says, "what I'm doing is like a preacher man who gets a calling and serves the Lord." Catching weak rays of sunlight on his doorstep earlier this year, a plastic tray contained a different tomato hybrid in each of its 128 slots, some unusually tall, some sporting purple stems or narrow leaves. Collaborating with local farmers and greenhouse owners, and with old connections in California, he transplants his starts and watches trial crops come to fruition.
One of his latest projects, the Skykomish tomato, shows encouraging resistance to the late blight that plagues growers in wet weather.
He's also been looking for ways to share his knowledge with younger generations. He sees so much of modern plant breeding as the domain of technology, constricted by proprietary information and genetic modification and seeds that can't be propagated for public use. For himself, he'd rather leave shared knowledge and "a legacy of helping each other."
Already, he says, "I feel good that I'm part of the food chain." He's glad his creations seem to have a permanent place in the public's hearts — and on their plates.
The Pedigree of 'Green Zebra' tomato by Tom Wagner
“Green Zebra has four heirloom-type tomatoes in the pedigree. The first breeding line was between 'Evergreen' and a crack-resistant red. The hybrid was red to start with, but an improved green evolved by the F-5 filial generation. The other parent was a cross of a green-striped red tomato that was a mutant out of an old market variety of the 1940's, and another heirloom that Gleckler's seed company had in an old catalogue of the 1950's.
I had to reselect for the green stripe (red and yellow when ripe) until I had better crack resistance and flavour by the F-6 selection. The hybrid of these lines created a hybrid F-1 that was red, and no little or no stripes.
Several generations of bulk harvesting of sister clones were evaluated repeatedly in the field followed by a generation in the greenhouse to get the tangiest green flesh with various levels of striping. The lines were in different groups of 5%, 10%, 60%, 80% striping intensities. I released the first seed in 1983 and the 60% striping level was called 'Green Zebra' at that time.”
- Additional Information
Packet Size 25 Seeds Common Name Salad Tomato, Heirloom Cross,
Vine / Cordon (Indeterminate)
Family Solanaceae Genus Lycopersicon Species esculentum Cultivar Black Zebra Hardiness Half Hardy Annual Fruit Purple/mahogany with vertical deep green streaks Height 150cm (60in) Spacing 60cm (24in) Season Mid-Season Time to Sow Sow early indoors from early April to the end of May Time to Harvest 75 to 80 days to maturity.