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  1. Tomatoes belong to the same plant family as potatoes, peppers and eggplant. (Solonaceae)
  2. Tomatoes are a new world plant that originate from the Andes in Peru and were bred and cultivated by the Aztec peoples. Tomatoes were brought to Europe in the 1500's. 
  3. Tomatoes should be started as transplants and planted outdoors two weeks after the last average frost in your area. If you grow your own transplants, don't start them too early as they quickly outgrow small pots.
  4. To prevent blossom end rot, ensure that tomatoes have consistent moisture. 
  5. Botanically speaking, tomatoes are a fruit.

Tomatoes are high in vitamins A, C and K, and carotene and lykopene. Check here for detailed information from the USDA National Nutrient Database for Standard Reference.

The Canadian Food Guide recommends that roughly half of the food on your plate should be fruits and vegetables.

Canada Food Guide: What's On Your Plate?

Growing outdoors

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Tomatoes prefer sandy loam, loam or clay loam soils for good fruit production. Prepare the garden soil well in advance, adding organic matter and compost if needed.  The soil should be of good tilth: soft, crumbly and easily worked. They also do well in containers filled with soil-less potting mix provided they are adequately fertilized.

Tomatoes need full sun for highest yields and are not suitable for partial shade or shady areas. If you have a partially shaded garden, you may be more successful if you grow them in a container in a sunnier spot. 

While tomatoes can be grown indoors, they typically do best outdoors. (See below for details)

Tomatoes require a long, warm growing season and must be transplanted in the Prairie garden. Tomato transplants can be grown in your home or purchased from a local greenhouse.

Starting your own tomato plants from seed

  • Start transplants at about 6 weeks prior to planting out, ideally about two weeks after your last frost free date in spring. In Saskatoon, your frost free date is May 13 so start indoors around the begining of April.
  • You can start tomatoes indoors earlier than April 1, but they will quickly outgrow their pots. Be prepared to pot them into larger pots to ensure a healthy root system.
  • The planting timeline can be shifted with season extending methods such as heating the soil and using water-based transplant sleeves like ‘Wall O’Water’®
  • Sow seeds 0.5cm deep in a commercial soil-less media containing peat moss or coir with perlite and/or vermiculite.  Soil-less media provides a disease-free environment as well as excellent drainage to minimize root disease problems. 
  • Use flats, pots or containers with bottom drainage holes.  At a soil media temperature of  24-32˚C, seeds will germinate in about a week. Seedling heating mats help to maintain warm soil temperatures for seed germination. 
  • Good lighting is crucial for the growth of healthy seedlings. 
  • Leave a fan blowing on your young seedlings as they grow to will help to grow heartier plants and to reduce some seedling diseases.
  • For more details, check out our article on growing your own transplants.

The ideal tomato seedling

  • Sturdy and short, and dark green in colour.
  • Has not yet flowered or set fruit.
  • Has a good root system but is not root-bound (tight, hard ball of roots that do not break apart when gently massaged). 
  • Has a strong and sturdy stem.  The internodes (spaces between leaves along the stem) will be small.  Transplants that are too tall will tend to break and dry out more easily once planted out into the garden.  Research has shown that stem diameter can be increased and height controlled by providing seedlings with constant air movement from an oscillating fan – or by lightly brushing seedling tops with a tea towel or stick at least 20 times daily.

Start fertilizing after the seedlings have their first true leaves. Wait a few days before fertilizing if you have transplanted your seedlings. Fertilize transplants two times/week using 20-20-20 water-soluble fertilizer.  Mix according to label directions.

Tomato transplants must be hardened off before transplanting outdoors.


  • Tomatoes must be planted as transplants and not sown as seeds. See our transplants tab for tips on growing your own transplants.
  • Tomato plants are a warm season crop so they are very sensitive to cold temperatures and frost damage. Be prepared to protect plants with covers or blankets in the event of late spring/early summer frosts.  It is best to transplant tomatoes into the garden after all danger of frost has passed.  The “average day of the last spring frost” in the Saskatoon area is typically May 13, but it's best to transplant a week or two after that date.
  • These timelines can be shifted with season extending methods such as heating the soil and using water-based transplant sleeves like ‘Wall O’Water’®.
  • Tomato transplants must be hardened off before transplanting outdoors.

Planting instructions

  • Gently massage the roots within the plug so that the roots will grow into the surrounding soil and not remain restricted within the ball.
  • When planting, cover the entire transplant “plug” or seed ball with soil to prevent the plant from drying out.  Exposed peat within the plug will act as a wick, drawing water away from the transplant and drying out the root ball.
  • Ideally, transplant on a cool, cloudy day. Hot, windy days will easily desiccate tender transplants. 
  • Tomatoes are unique in that they do better planted deeper than normal. Plant them deeply in the ground so that the soil level is just below the lowest leaves. You can also dig a trench and lay the plant in it to bury long stems. Ensure that the whole stem is covered with soil up to the the first set of leaves. The advantage of this is that the stem will produce roots and establish a larger, stronger root system.
  • Avoid planting into cooler soil. For extra protection for your newly planted tomato transplants, place tin cans or milk cartons with the tops and bottom removed around plants and insert containers several centimeters into the soil. Not only does this provide some wind protection and increase soil temperature, but it may also discourage cut worms.
  • Tomatoes should spaced according to the type of tomato:
    • 30 - 60 cm (12" - 24") apart for determinate varieties (bush tomatoes)
    • 35 - 50 cm (14" - 20") apart for staked indeterminate varieties (vine-type tomatoes)
  • Water-in the transplants with a starter fertilizer higher in phosphorous for good root growth (ex. 10-52-10) Mix according to label directions.

Don't forget to label what you planted. It's also helpful to draw a map or take a photo of your vegetable garden to help you track planting locations and success each year. This information is critical if you're rotating your crops to help prevent insect and disease issues.

  • Gardeners who want to get an early jump on the growing season, can warm up the soil with ‘Wall O’Water’®: a series of plastic tubes filled with water joined together to form a wall of water around the transplant.  ‘Wall O’ Water’® can protect plants to -11˚C.  Tomato transplants could be planted out at least 2 weeks earlier on the Prairies provided the soil under the ‘Wall O’ Water’® has also been warmed.
  • Tomatoes are a ‘warm season crop’. This means they prefer warm temperatures and very sunny conditions for optimal growth.  Tomatoes benefit from planting in black, clear or dark green plastic mulch. The mulch increases soil temperature as well as conserving soil moisture and suppressing weed growth.
  • Tomatoes also benefit from supported crop covers throughout the season; the covers will warm the air surrounding the plants and encourage plants to flower, fruit and mature earlier than outside covers.  Because most tomatoes are self-pollinating, it is unnecessary to remove the crop covers during the growing season except to weed.  
  • Perforated clear plastic tunnels or covers are not recommended as temperatures can be extreme, which can cause tomato flowers to abort.     
  • Factors to consider when deciding what tomato cultivar to grow include: taste, days to maturity, end use, type of tomato, disease resistance and availability.
  • There are thousands of different types of tomatoes available as seed or transplants.
  • Tomatoes that need more than ’70 days to maturity’ will probably not fully mature during an average Saskatchewan growing season.
  • Tomatoes have a genetically determined growth habit in terms of their size and are divided into two broad categories:
    • "Indeterminate" tomatoes continue to grow in height and can reach up to 1.5 meters tall in a Saskatchewan summer. They are sometimes referred to as "vine" tomatoes, but they cannot support themselves and must be staked. These tomatoes benefit from pruning. They tend to keep producing flowers until frost and the fruit ripens over a long period of time. The best cultivars are ones that ripen in 65 days or less.
    • "Determinate" tomatoes are a bush type that top out at 30 - 90 cm, depending on the cultivar. They generally do not need to be pruned or staked. They produce many short branches with flowers and fruit on the ends and the fruit tends to ripen all at once, over a 2 - 3 week time period and are recommended for our short growing season in Saskatchewan. Cultivars that ripen in 70 days or less are recommended.
  • Tomato fruits vary a lot and are informally categorized as:
    • "Cherry" or "Grape" type tomatoes are small, less than 3 cm in diamater and are good for fresh eating or in salads.
    • "Beefsteak" refers to meaty but juicy tomatoes that can be very large in size.
    • "Plum", "Roma" or "Paste" type tomatoes are meaty with few seeds and are good for canning.
    • "Salad" tomatoes are mid-sized and are good for fresh eating.

 Here are cultivar recommendations from the North Dakota State University Cultivar Trials, as they share a similar prairie climate and soils. You may download their list here: North Dakota State University Vegetable Cultivar Recommendations for 2021

  • Cherry: Juliet, SunSugar, Supersweet 100, Sweet Baby Girl, Yellow Pear.
  • Fresh market: Big Beef, Bush Early Girl, Celebrity, Early Girl, Goliath, Mountain Fresh Plus.
  • Paste: Roma VF, Viva Italia. Heirloom: Brandywine, Cherokee Purple, Striped German, Stupice, Wisconsin 55.

The following cultivars are recommendations from the University of Saskatchewan vegetable program field trials which were conducted from 1989 through 2016. 

  •  Early season: ‘Bella Rosa’, ‘Duchess’, ‘Early Girl’, ‘Manitoba’, ‘Oregon Spring’, ‘Pik Red’, ‘Scotia’, ‘Starfire’, ‘Tribute’

  • Mid-season: ‘BHN 961’, ‘Booty’, ‘Celebrity’, ‘Matina Organic’, ‘Sunbeam’, ‘Sunchief’, ‘Sunstart’, ‘Swift’, ‘Taxi’

  • Late-season: ‘BHN 399’, ‘BHN 537’, ‘Grace’, ‘HY-Beef 9904’, ‘Jackpot’, ‘Classica’, ‘Daiquiri’, ‘Lemon Boy’, ‘Miracle Sweet’, ‘Mountain Fresh’, ‘Pilgrim’, ‘Siletz’, ‘Early Cascade’, ‘Sunbrite’, ‘Sunmaster’, ‘Sunsation’, ‘Super Fantastic’, ‘Ultra Sonic’, ‘Mama Mia’

  • Heirloom: ‘Black Prince’, ‘Black Russian’, ‘Early Annie’, ‘Fireworks’, ‘Harbinger’, ‘Mini Orange’, ‘Orange King’, ‘Red Currant’, ‘Sasha Altai’, ‘Siberian Red’, ‘Silvery Fir’, ‘Oxheart’, ‘Yellow Currant’, ‘Yellow Plum’



Pruned vs unpruned tomatoes - which is better?

Tomatoes benefit from a steady supply of soil moisture throughout the growing season. Consistent moisture will prevent blossom end rot.

Actively growing tomato plants need 2.5 cm water/week. They also benefit from mulch, in the garden or in a pot. 

Fertilize tomato plants using a side dressing of compost. Another way is to use a granular fertilizer formulated for vegetables according to the manufacturers instructions. Tomatoes grown in containers in soil less potting mix need regular fertilizing with a water soluble 20-20-20 fertilizer applied according to the manufacturers instructions - usually once or twice a week. 

Avoid using high nitrogen fertilizers such as 32-0-0, which encourages leafy growth at the expense of fruit production. 

Tomatoes can also benefit from supported crop covers throughout the season; the covers will warm the air surrounding the plants and encourage plants to flower, fruit and mature earlier than outside covers. Because tomatoes are self-pollinating, it is unnecessary to remove the cloth covers during the growing season except to weed.

Perforated clear plastic tunnels or covers are not recommended as temperatures can be extreme under this clear plastic, causing tomato flowers to abort.


Pruning depends on the type of tomato plant you are growing. Determinate are the bush type of tomato plants which are limited in growth. These are rarely pruned except to improve air circulation if the plant is really dense. Indeterminate tomatoes are another story. These are the vine type of tomato plants which grow and grow and grow.... you know the ones! They need support or staking for good fruit production and should be pruned weekly. We found that pruning vine tomatoes improves fruit production. Look for suckers or new growth at the leaf cluster on the main stem. It's easiest to remove these when the suckers are small. Pinch these out with your fingers if small and tender, or make a clean cut with sharp scissors or pruners if these have gotten larger than you intended. If your vine (indeterminate) tomatoes have never been pruned, use your best judgement about how much to remove. Try not to remove more than about 10 - 15% of the plant at one time or the plant will become stressed. Keep the best ones with fruit and flowers to mature for the rest of the growing season. Continue to prune new suckers weekly to keep your indeterminate vine under control.



Tomatoes are not suitable for fall seeding.

Coming soon


Growing in containers

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Tomatoes can be grown in a container indoors or outdoors.

Plant a single tomato plant in a large container with a hole in the bottom. The container should be at least 8 liters (2 gallons) or larger to allow space for a healthy root system.

See: Vegetable container gardening

Tomatoes can be grown indoors but need supplemental lighting.

See our Growing indoors page for detailed growing advice.

Using indeterminate tomatoes to grow a tomato tunnel

Choose an determinate or bush type tomato for growing in a container if you do not want to stake the plant. 

Indeterminate or vine type tomatoes can be grown in containers provided they are staked.



Saving seeds

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Seeds are expected to be shelf-stable for one year from date of sale if purchased from a reputable retailer. If you wish to save your seeds beyond that, you should store them in the fridge in a jar. Seeds lose viability quickly if they dry out too much or get too warm.

The life expectancy of tomato seed stored under favourable conditions is between 3 and 7 years.

Seeds stored under less favourable conditions will show poor germination after just a single year of storage. Beyond this, you can expect your germination rates to go down (ie. not all of your seeds will grow, but some might). To test your seeds, you can do a simple germination test. Follow the link for instructions. If you are still getting some seeds germinating, seed more thickly and thin any extra.

Tomato seeds can be saved from “heritage” or “open-pollinated” plants. If the plant tag or seed package from the original plant says “hybrid”, the plants grown from seeds collected from hybrid plants won't look the same next year.

This fermentation method gets rid of the pulp on seeds which inhibits germination.

  1. Let two or three tomatoes ripen as long as possible on the plant before frost. Avoid saving seeds from diseased plants as disease can harbour on the seeds and be carried over.
  2. Cut open the tomatoes and scoop the seeds into a bowl.  Seeds have a slimy coating called pulp. Put the seeds and pulp in a container with a lid. Label the container with tomato name and year. Add some water – the seeds and pulp will float to the top.
  3. Keep this in a warm place for 3 – 5 days. The warmth causes the pulp to rot and ferment. This releases the seeds which will drop to the bottom of the container.
  4. Once the seeds have separated from the pulp and dropped to the bottom of the container, add some water and pour off the rotted pulp.
  5. Fill the container again. Let the seeds sink to the bottom and pour off the water.
  6. Now dump the seeds and water into a fine mesh strainer. Rinse under cool water.
  7. Put the seeds on to a plate or tray and spread them out to let them dry. It may take several days for the seeds to dry completely.

Or, you can simply wash and strain the seeds and spread them on a plate or tray to dry. Before you plant these seeds, pre-soak them in water for a few hours to get rid of the coating.

How to store seeds
Vegetable seeds can keep for several years if you store them properly. Seeds should be stored in a cool, dry, dark place. Moisture, heat and light can cause seeds to sprout or rot.

  • Place your seeds in envelopes or make your own envelopes out of foil or waxed paper. Label with name of the seeds and the date (month and year) you harvested them.
  • Place your envelopes inside an airtight container. To help keep seeds dry, place about a tablespoon of dry powdered milk in a paper towel or piece of cloth, secured with a twist tie or piece of string. The powdered milk will absorb humidity and keep seeds dry inside the airtight container.
  • Put the container in the refrigerator. Do not store seeds in an unheated shed or garage. These places are either too moist and/or too cold for seed storage.




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  • Harvest tomatoes early in the day before temperatures rise.
  • Tomatoes can be harvested green, or just starting to turn colour, or fully ripe.
  • The optimal temperature for ripening on the vine is between 21 ˚C and 24 ˚C. Any cooler or hotter and ripening slows down significantly. In hot weather, pigments like lycopene and carotene which give tomatoes their lovely colors, are not produced.
    • It is a myth that removing leaves from your tomato plant to expose fruit to sunlight will encourage tomatoes to ripen. It seems counterintuitive, but sunlight is not needed to ripen tomatoes. In fact, tomatoes on the vine exposed to direct sunlight can heat up which inhibits ripening or can cause sunscald.
    • Same goes for extra fertilizer – it will not speed ripening.
  • Closer to the end of the summer, reducing water can stimulate ripening, but then temperatures tend to be closer to the optimal range for ripening at that time of year anyway.
  • Ideal temperatures for ripening and storing tomatoes off the vine:
    • Mature green tomatoes will store for 2-6 weeks at 15˚C to 22˚C. Mature green tomatoes have shiny skin. Green tomatoes with a matte skin texture are not mature and are less likely to fully ripen.
    • Tomatoes at the breaker stage (just starting to turn colour) will fully ripen off the vine at 15˚C to 22˚C.
    • Ripe red tomatoes will store at 15 - 22˚C for 5-10 days, out of direct sunlight. 
    • Temperatures below 10˚C will cause tomato chilling injury, resulting in rot and poor ripening colour and quality. Never store tomatoes in the fridge.

  season-extending options.

Harvest ripe tomatoes by lifting the fruit upward from the bottom - most of the time the tomato will naturally "break" off the stem. 

If harvesting green tomatoes that don't break easily from the stem, snip the stems to remove the fruit. 

Smaller tomatoes such as cherry or grape types can be harvested by snipping the entire stem of clustered fruit.


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  • Ideal storage conditions for freshly harvested tomatoes are 15 - 22˚C, out of direct sunlight. 
  • Temperatures below 10˚C will cause tomato chilling injury, resulting in rot and poor ripening colour and quality. Never store tomatoes in the fridge.
Dehydrating tomatoes

Tomatoes can be frozendehydrated, or canned.

Tomatoes are a low acid food and must be processed using a high-pressure canner designed for canning to process the food to the temperature necessary to destroy botulism spores. Without the addition of an acid, high-pressure canning is the only way to guarantee safe canning. 

However, if you are processing tomatoes with the addition of vinegar or lemon juice (which changes the acidity), then a boiling water canner may be used.

Cooking and preserving

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Powdered tomatoes


Dehydrating tomatoes

Alternative ways to eat common vegetables



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Tomatoes require care, especially when it comes to water. Keep tomatoes evenly moist (but not sitting in water) for general health and to prevent blossom end rot. Managing their needs for water, light and soil helps tomatoes to be more resilient and resist insect and disease problems. Most years, the primary issue with tomatoes is frost or inconsistent watering.

Hot, dry summers are especially problematic as high heats may cause tomatoes to abort their flowers.

See the Common problems tab on this page for advice on other specific tomato issues.


Common questions

Research and student activities

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Hybrid tomato seed technology