Tomatoes 101 by Rob Brown Horticulturist specializing in Vegetable and Nursery production. Flattop Farm, LLC
Tomato History Native to the Americas and brought to Europe by Spanish conquistadors. Aztecs used it them as early as 700 AD. Tomatoes are actually fruits, though they are often thought of as vegetables – The US government taxes them as vegetables. Thought to be a poor person’s food and were thought poisonous by rich Europeans originally because high acid tomatoes caused lead to be leached from pewter silverware and caused sickness/death. Poor people did not use such nice silverware and didn’t get sick. Popularity grew in times right before the Civil War and most all “heirlooms” originated from no earlier than the Civil War. 170 million tons grown in the world per year on 12.4 million acres. 16 million tons grown in the US – 8% for the fresh market. California and Florida
Growing tomatoes in Alaska Perception that it is impossible to consistently grow tomatoes without a greenhouse/high tunnel Short & inconsistent growing season, cool soils, low night temperatures Perception that many tomatoes grown outside don’t have good flavor. The most successful tomato production is done in high tunnels and greenhouses in Alaska, however there are varieties that can be consistent outdoors if grown correctly. Phytosanitary inspection requirements to prevent harm to the potato industry are necessary to import Solanaceous crops (potatoes, tomatoes, etc..) into Alaska. High shipping costs mean that starts have to be bought from box stores which may not be suited to Alaskan growing. Many people grow from purchased seed or buy local starts, where more appropriate varieties are available.
Let’s be honest here! Gardeners will tell you in the Lower 48 about their “secret” to growing great tomatoes. In Alaska, growing tomatoes successfully every year takes more than just a secret. It takes a well-rounded, all-encompassing approach with advance planning and lots of trial and error. There are things that are easy to grow here and tomatoes are not in that category for everyone. But they can become easy when you learn from past mistakes and keep trying. What I present to you today is a result of constant trial and thousands of errors. The rewards of gardening are so much more than a delicious meal, so please do not be discouraged if you fail to get what you envisioned when you began. I have killed more plants than everyone here combined!
Top 10 things to know about growing Tomatoes in Alaska - # 10 10. Choose a variety that is appropriate for the season you are growing in. Greenhouse grown – maximum is 75- 80 days, ideally ≤75. Outdoor grown <68 days to first mature fruit from transplant. Tags and descriptions of tomatoes often give number of days and it is days from transplant, not from seed. That also means at normal temperatures, which are not that normal in Alaska! May 27 to August 10 = 75 days. So an earlier variety will increase your chances of success.
Top 10 things to know about growing Tomatoes in Alaska - # 09 9. The variety should fit the space you intend to grow in. Indeterminate tomato (Indet.) = vining type that does not stop growing after fruit set 4- 5’ or taller – Many branches are produced which do not all produce ripe fruit during the Alaskan growing season. Often called “suckers” for being thought to “suck” the energy from the plant. These need removal to have optimum production. Training Indet. plants produces more ripe and larger fruits in our short growing season and the plants grow taller. In Alaska, I consider a successful Indet . tomato plant to be one that produces 4 or more ripe “trusses” or branches of fruit during the growing season. These plants need support by staking or tying methods. Determinate tomato (Det.) – Bushy type that stops growing when the main stem ends in a flower bud and sets fruit. ≤2 - 4 feet tall. Determinates don’t need much pruning, but they should have enough leaves in the middle removed so that there can be airflow through the plant so it doesn’t mold. I still recommend staking as the plants will get top heavy as the fruit grow. May produce small or large fruits, depending on variety. Semi-determinate – has characteristics of both Indet. and Det., but is typically about 4 feet tall by the end of the growing season here. “Dwarf” tomato are plants that finish at 18” - 4’ tall and may be Determinate or Indeterminate. May produce small or large fruits. “Micro - dwarf” are plants that typically get no more than 1 -1.5 feet tall during the growing season. Typically cherry sized fruits.
Unripe tomato truss on “Black Strawberry” tomato
Top 10 things to know about growing Tomatoes in Alaska - # 08 8. Plan ahead to optimize the growing season. Start seeds indoors Between March 1 & April 15. Germinate seeds by planting ¼” deep in potting media at 70F . Tomato seeds can keep for 5-10 or more years if stored correctly. Provide 12-18 hours of light, using grow lights, or a combination of grow lights and natural light works well. Plan to transplant once or twice to larger pots as they root out. Having a 5” or 1 gallon pot that is rooted out, but not too rootbound is what I prefer. Keep temperatures at 75F day and 60F night, if possible. Incorporate a fertilizer with a 1:2:1, or 1:2:2ratio (ie. 10-20-20) and be sure to find one or make a combo that has micronutrients like Calcium and Magnesium. Epsom Salt, Alaska Sea Ag Fertilizer, Azomite, and mycorrhizae (beneficial fungi) are a good combination. Foxfarm Ocean Forest, Pro Mix (BX/HP or others) are preferred pre-made potting soils and may be combined for transplanting. Liquid feed once every 10-14 days – Foxfarm Bloom is great. Place plants outside for good no earlier than Memorial Day (May 27, 2019). This means that you may should acclimating, or “hardening them off” 10 days before then. Start acclimating with 3-4 hours sun, then bring them in and work up the time each day. 3 days before beginning acclimation, start cutting water a bit, give them a kelp foliar spray and watering, and no fertilizer until hardening is done. Plants may need to be brought in or protected during June if Night temperatures get much lower than 50F .
Top 10 things to know about growing Tomatoes in Alaska - # 07 7. Give them the warmth they crave! The ideal average temperature for tomatoes is 75F , but they thrive up to 90F . So, make up for the cool night temperatures by modifying your growing area to be warmer during the day and night, if possible. Lowest night temperature of 55F should be a goal, but warmer is better. Utilize areas where there is long sun exposure, at least 12+ hours of direct light, but more light is better. Place a max/min thermometer next to your tomato to track the temperature. Modify the climate to warm up the air AND soil. Plastic or biodegradable “mulch” will warm the soil. Soil temperature that is higher than 65F at 3” down is necessary for good flavor. A soil thermometer is a cheap investment which will give you great information. Pots get very warm if they have direct sunlight, but can be slow to warm up if not. That’s why I prefer a larger pot, so that it insulates a bit. Use reflected heat from a patio wall, make or purchase a mini greenhouse. Temper your water, if you can. Use lukewarm water so you don’t shock the roots with cold water.
Soil-Warming, Soil Thermometer IRT/Plastic/Biodegradable “Mulch” Maximum/Minimum Thermometer
Top 10 things to know about growing Tomatoes in Alaska - # 06 6. Prepare your soil No matter if in pots or in the ground, soil is equally as big a limiting factor as what’s going on above the ground. Soil preparation is very important Compost, fertilizers (including micronutrients), and mycorrhizae should be mixed into your soil before planting. Talk with the garden center about what products they carry that will work best. Tomatoes like calcium and magnesium. Egg shells take too long to break down unless they are pulverized. I prefer Dolomitic Lime at the recommended rate. I incorporate 2-3 Tbspn Epsom Salt per planting hole and then incorporate again 6 weeks later. I use Azomite for micronutrients and Alaska Sea-Ag at a high rate. Liquid feed your plants to keep them going. I alternate Liquid Fish Emulsion and Foxfarm Bloom for the first month, then only Bloom, and fertilize once every 2 weeks. I also add kelp to those. Prepare soil for 12- 18” deep. I prefer a slightly raised bed with two heaping wheelbarrows full of compost mixed in per 100 square feet of row space.
Top 10 things to know about growing Tomatoes in Alaska - # 05 5. Plant deep, but not too deep. Tomato plants are able to grow new roots through their stems if planted under the soil. This can encourage vigorous growth and drought tolerance. Remove the leaves going up the stem for about 4- 6”, up to 1/3 the height of the plant. I prefer to lay the plant on it’s side in a kind of trench. The cool soil in Alaska slows down root development along the stem and the soil is warmer towards the surface. So the roots develop faster when laid down, as opposed to being dropped deeply. Slightly bend the above ground part so it is mostly oriented the correct way. Be careful not to bend it too much or it can break.
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