Tomatoes

Everything you need to know about growing tomatoes.

Tomatoes

Tomatoes are by far the most popular crop grown by individual home gardeners and are by far the plant we get asked about the most. In our climate we can grow tomatoes from transplant in 2-3 months and each plant can conceivably produce abundant tomatoes for several months if not a few years in the right conditions. The reason a home-grown tomato tastes superior to store bought is in the vine ripening. Tomatoes that are grown on farms for market are picked when they are unripe, green with a slight tinge of orange and then forced, with the addition of ethaline gas, to become red. They lack the sugar and acid that would develop naturally if left on the vine. Moreover, there are literally 1,000’s of tomato varieties, but the ones for market are chosen on shipability, uniformness for display, packaging considerations, and ease of growing/harvesting. To the contrary, the tomatoes homeowners choose to grow are usually based more on flavor, size, and uniqueness. Here are a few of our tips and observations from growing tomatoes over the last two decades.

SOIL

Tomato plants can grow in just about any soil as long as it doesn't remain constantly soggy. Common fatal diseases like Fusarium and Verticillium typically “build up” in the soil so it is a good idea to not plant a tomato (or pepper, or eggplant, or potatoes) in the same place for more than a year or two at the maximum. You can come back to that area after 3 years off. Unrelated plants like beans, corn, squash, lettuce, cabbage, radish, strawberry etc are not affected. Many hybrid tomato varieties (discussed below) are bread to resist these diseases and can tolerate being planted in the same soil for a two or three years in a row, but even these types will eventually gradually decline in production or not thrive at all. Tomatoes grow very well in containers if given ample space and water in the summer. A pot should be large enough to fit at least 1 cubic foot. Please replace the soil in containers yearly if you use soil bought at big box retailers.

WATERING 

Tomato plants, like most crops, prefer consistently moist, but not wet soil. Most tomato types are highly forgiving of short periods of drought, but the fruit may crack or get blossom end rot (see below) if not given consistent water.  Signs of drought stress include curled leaves, or visible wilting. Watering should be on the ground and not on the plant if possible as it is important that tomato leaves do not stay wet for long periods. Water droplets can be the perfect environment to germinate disease spores that can infect the leaves.  If the weather is warm or windy and dry, you can irrigate any time of the day.  Under cool humid conditions typical in spring through early summer (June gloom) try to water between mid-morning and early afternoon.  If you can avoid getting the leaves wet, as with drip irrigation, water anytime, day or night, and maybe two or three times a day in the heat of summer.  In native, mineral based, soils you probably cannot overwater. In amended soils containing a lot of compost (most commercial potting soils) make sure to allow the soil to look dry on the surface before the next irrigation or root rot issues can develop. 

EXPOSURE AND TEMPERATURE 

Although tomatoes grow best in full sun, I have grown many types of tomato plants in half shade with good results. I would say “light shade” is fine, but deep shade probably wont give you optimal results. If growing in containers, you can moving them into part shade when the daytime temperature soars over 100 degrees and in the full sun at other times. This will give great results. Tomato plants grow best when daytime temperatures reach 85 degrees and nighttime temperatures remain above 55 degrees F.  The flowers on many varieties will fail to set when night temperatures are below 55 degrees or when day temperatures are above 95-100 degrees F. So, you want to plant tomatoes early enough in the spring to have a suitably large plant when these conditions arrive. Basically you can start tomatoes in a greenhouse around Jan/Feb in our climate and plant transplants in the garden in March/April for best results. Planting flowering pollinator plants that attract bees nearby, or gently flicking flowers stems mid-day can stir up the pollen to help the flowers get pollinated and increase fruit production.  

FERTILIZING 

Contrary to the myriad of fertilizers that prominently display a picture of a tomato on the bag, tomato plants are relatively light feeders.  In the short term just about any fertilizer works. The “Osmocote plus” brand in a pink bag or jar is a good non-organic option that is very forgiving and has micronutrients. If plating in an established bed where the soil is permanent, it is best for the plant, and your soil, to apply fertilizers from an organic source. Organic fertilizers generally cannot be over applied but do take some time to break down and become usable for the plants. Again, you don’t need to be particular but a balances approach is fine.

SUPPORT 

Tomato plants technically do not require support, however, if given some the fruits are less prone to insect and rot damage, the plants will take up less space, and they are generally easier to harvest. Most home gardeners prefer to stake or cage their plants. Conventional farms do it both ways.  Mechanically harvest crops are usually allowed to sprawl while staked plants are generally trellised. Staked plants are more subject to sunburned fruit. Honestly I can write a whole article on the many types of support, from the Florida weave to the many commercially available cage solutions. In my personal garden, I generally initially cage our tomatoes and then let them sprawl as they eventually overwhelm the cage. My best advice here is that bigger is generally better on these supports as a mature tomato can grow to 6’ or taller and can weigh a considerable amount. The cheap, usually brightly painted, wire cone shaped cages are practically useless for tomatoes, although are great for peppers and eggplant.   

PESTS

I have yet to see a tomato grower who hasn’t had tomato horn worms at some point. These giant caterpillars are the larva of night flying “hummingbird” moths. These caterpillars start very small but quickly (3-4 weeks) can be the size of an adults finger. Just a few of these can destroy a plant. They are hard to see but can simply be plucked off or you can kill them with a product containing an organic pesticide containing Spinosad.  The most commonly available Spinosad liquid spray is “Captain Jacks Dead Bug Brew.” Spinosad is a byproduct of rum distillation and lasts about 2 weeks on the plant. That means you should treat once a month, starting in mid-June, to keep your plants free of harmful sized caterpillars.   Another, albeit older, organic option is Bacillus thuringiensis, sold under the moniker Bt or Thuricide.  This is actually a caterpillar disease that doesn’t affect humans or any other life form but caterpillars and should be applied every 2 weeks. It has a very short shelf life so buy from a reputable source.

If you have a large garden, cucumber beetles can be a real issue as they spread disease. There are no great organic options for control but if you have this issue give me a call and we can work through options.

Most other pests are uncommon or fleeting; bad one year not to return for a few more. These include aphid, stink bugs, snails/slugs, and cut worms. All can be somewhat controlled with Spinosad, but probably wont be an issue. Some varieties are prone to spider mite infestations as well. You will see microscopic orange to red fuzz and webs on leaves. A biweekly blast of water should keep them at bay. Mites are actually spiders that feed on individual plant cells. A telltale sing is leaves the are not as green. If the weather is cool, neem oil works as well.

 DISEASES 

As noted above, during late winter into spring, and sometimes early summer the diseases associated with wet leaves are most common  When we have very foggy and light mist type spring weather Late Blight becomes a real threat.  This is the same disease that caused the Irish Potato Famine and usually appears first on your potatoes if grown nearby.  The water droplet harbors the disease that appears as small dark spotting that quickly turns surrounding stems black.  Cut off infected parts quickly and disinfect clippers between cuts. If caught early enough you can usually cure the plant.  Monterey Brand “Garden Phos” is a liquid phosphorus fertilizer/fungicide that can help prevent Late Blight.  Other mildews and blights can usually be cut off as well.   Although its not a disease per se, many tomatoes can get blossom end rot. It is especially common with large fruited varieties and young plants or plants that get drought stressed. Blossom end rot is when the bottom of the fruit turns dark brown and hard. It is caused by a failure of the plant to properly finish the fruit due to a lack of calcium.  In my experience it's usually not a lack of calcium in the soil, but rather a underdeveloped root system or an inconsistent watering schedule that pulls the calcium out of the fruit. If observed, fix your water first, then you can treat the plants by spraying the developing fruit with a product containing calcium weekly. Adding egg shells does not work. Honestly, usually this happens in young plants and when the roots develop the problem disappears.  Cherry or smaller Tomato varieties are rarely afflicted.  

PLANTING DEPTH

Tomato plants are one of the few plants that readily form roots on their stems. We can take advantage of this quirk of nature and plant them “deep.”  I generally recommend planting your young plants about 1" deeper than the soil level in the container thy come in so that they can root directly from their stem into your soil.  Do not burry leaves. Gently pinch off lower leaves. “Leggy” or very tall young plants can be planted up to 4” deeper than their container, pinching off leaves as noted above.

HEIRLOOM VERSUS HYBRID TOMATOES

Heirloom Tomatoes

Heirloom used to mean something that was passed down generation to generation. Now it means that it has been inbreed for 7 generations so that its two chromosomes are nearly identical and its seeds sprout plants that are extremely similar to the parent. All heirlooms must be "open pollinated".  This basically means that the seeds are collected from fruit that results from the flowers being pollinated by the same variety.  As long as there is no other variety of tomato plant within 25 feet or so of the heirloom, there is little chance of significantly different genetics in the resulting fruit's seeds.  The heirloom is genetically "stable".  Tomato gurus generally agree on four types of heirlooms. Open pollinated varieties that have been sold for several generations. Stable varieties that are true family heirlooms. Heirlooms that have been hybridized to improve them then de hybridized by breeding back 7 generations.  Chance varieties that appear randomly. Heirlooms can provide the best or at least the most unique or distinctive flavor. Think Brandywine, German Green, Black krim.

Hybrids are babies of specific crosses of two unique parents, and are usually crossed by humans on purpose. Some of the most marketable varieties are hybrid and can provide the heaviest production, the most vigorous plants and still have a good flavor. Common hybrids are Early Girl, Champion, Celebrity, Big Beef, and Better boy.  Many hybrids are also bread with disease resistance in mind and can perform well, even for those of you who don't rotate your crops properly. Being a hybrid doesn't insure a good outcome.  Hybridizers try many combinations before finding one that is superior.  An easy way to think about heirloom vs hybrid is with dog breeds. If a poodle is bread to another poodle over many many generations you would readily assume the puppies will look nearly identical to a poodle. This would be an heirloom breed. Unfortunately with all the inbreeding certain genetic weaknesses become an issue but it leads to a very wide variety of extremely unique types. A bulldog looks nothing like a poodle but is genetically pure to its own type. Now if you breed a poodle to say a Labrador, the resulting puppies are a hybrid called a Labradoodle. The puppies are predictable but do not look entirely like either parent.  

DETERMINATE VERSUS INDETERMINATE TOMATOES

Determinate tomato plants were made for farming. They generally grow more like a bush without need for staking and produce flowers on all parts at the same time and stop growing as the fruit is developing.  The entire crop ripens basically at the same determined time allowing farmers to harvest all at once. These types are not as common for homeowners but are sold as dwarf or patio types often. Determinate types do not require pruning.

Indeterminate tomato plants will flower and fruit as the plant grows into a sprawling vine.  This means that the new leaves, branches, and flowers are constantly forming so that the oldest section ripens first followed by the younger portions.  This means you'll harvest fewer at a time, but constantly over a longer period.  Most home grown tomatoes are indeterminate. Indeterminate varieties benefit from pruning and that is a topic for a later post.  

SHAPE AND SIZE

Cherry-types or smaller varieties always seem to do well regardless of cool and hot weather. Grape and other cherry/paste crosses (grape shape) are becoming more popular than traditional cherry as they don’t explode when pierced with a fork in a salad. Most cherry types will produce more than you'll ever eat and you will need to control their sprawling growth.

Slicers are the in the medium racquet ball to tennis ball sized or bigger. They are bread to have a fairly uniform shape and are meaty. These are the tomatoes you see in cartoons and pictures, round and full. Although red is traditional, slicers, like other shapes come in all colors.

Paste tomatoes have the highest meat to seed ratio and are best for sauces. They tend to be more cylindrical in shape. Roma and San Marzano are the most common however there are many off shoots of these types.

Beefsteak are the big boys of the tomato world. They are prone to cracking and Blossom End Rot but can grow to 1-4 lb. They have a non uniform shape and also come in many colors.