Here is absolutely everything you ever wanted to know about growing tomatoes in the Calgary garden: choosing, planting, supporting, pruning, amending, protecting and picking.
The 2 Types of Tomatoes
Before we get into the nitty gritty, let's talk about the two major types of tomato plants: indeterminate tomatoes and determinate tomatoes. This is an important distinction as it will determine the type of support we will need to use and how they will need to be pruned. How and when we want to use our ripe tomatoes will also be affected by the type. So know the difference and purchase the type you want purposefully. You may also find a couple of tomatoes out there that are listed as semi-determinate. These uncommon tomatoes have the vining habit of indeterminates but are earlier maturing, like the determinates.
Transplants
In our climate, tomatoes cannot be direct seeded into the garden. They must be planted as transplants. These are young plants that were started from seed indoors, usually in April. We just don't have enough growing days to mature and ripen them from seed outside. And we also don't have warm enough temperatures in early spring to germinate the seeds. They are Mediterranean plants after all.
Purchasing starter plants
There are two ways we can get tomato transplants. We can either purchase them at our local garden center or big box store, or we can grow them from seed ourselves inside our homes. Store bought plants are a good solution if you are short on time or space. The trade off is in the price and number of varieties available. Plants that are already started for you are going to be far more expensive than seeds. Depending on size, they can range from $2 to $25. There are also going to be a limited number of varieties to choose from. Big box stores may only carry one or two different tomatoes. A large garden center may have up to 10 or 12 varieties. Often, there will be little information besides the variety name. You will need to do your own research on which type (determinate or indeterminate), size, climate suitability and features each has. Or hope that someone working there knows their tomatoes.
When selecting tomato transplants there are a couple things you should look for to ensure that you get the healthiest plants possible. It may be counter-intuitive, but bigger is not always better. Just like when we start our own plants, we want short and sturdier plants with thick stems. Don't be tempted by tall skinny supermodel plants. Thicker stems are stronger and can move more water and nutrients from the roots to the leaves and fruit. That means better fruit and less chance of breakage. The next thing you want to look out for is root bound plants. Take a look and see if there are lots of roots trying to escape out the drainage holes on the bottom of the pot. If you can, tip the plant a little bit out of the pot and see if the roots are wrapping around the outside of the soil. Both of these are signs that the plant has been in its current size pot for too long resulting in a nutrient and water stressed tomato plant. Wilted leaves are another sign of serious water stress and should be avoided. Signs of disease and pest issues, such as discolored leaves, chewed leaves, white powdery residue or spots should be a hard pass for you as well.
Lastly, be aware of how your plants have been treated. If the use of pesticides and chemical fertilizers are an important issue for you (and they should be), make sure to find out if they were used on the plants you are interested in. And, find out if they were used on the plants before they were shipped to the store. If an employee doesn't know, make sure they find out for you. These are vegetables that you and your family will be eating and it is important you are comfortable with what is on them.
Starting your own plants from seed
The best part of starting your own tomato seeds, is the vast number of varieties available. When you increase your search to online seed companies you can literally choose from a hundred different types. That gives you a lot of choice to get the tomato that is perfect for you. Or the 10 tomatoes that are perfect for you! Starting your own seeds does involve some initial cost (such as soil, containers and lights), but seeds will be much cheaper (less than $1 each) than buying plants and most equipment you only need to buy once. For step-by-step instructions on how to grow tomatoes from seed indoors, check out the article All About Seed Starting.
What Variety Should You Choose?
Picking which varieties you are going to grow this year can be overwhelming with the number of choices. To help narrow it down, there a few things you should consider.
First, make sure the variety is appropriate for our climate. In Calgary, we usually plant out tomatoes mid-June (when night time temperatures are +10 C or warmer) and they need to grow, flower and ripen before we get a good frost. Our average first frost date is September 15th. That gives us around 92 growing days. We need to ensure that the days to maturity of our desired variety is no more than 92 days. (Days to maturity is from transplanting outdoors, not from seeding.) Some tomatoes have 60 days to maturity and some have 120 days. Take a look before you buy and make sure it is right for your climate!
Next, think about size. Are cherry tomatoes that you can pop in your mouth as you stroll through the garden your thing? Even smaller grape tomatoes for the kids' lunches? Big, huge tomatoes for slicing onto a juicy hamburger or BLT? How about some of each?
If you are thinking of making tomato sauce or preserving them in some other way, Roma or paste tomatoes may be what you are looking for. They have less juice and seeds than other tomatoes, making them perfect for sauce. They are also most often determinate tomatoes which is convenient because they tend to all ripen at once. Perfect for making a big batch of marinara.
Alternatively, if you want a constant supply of ripe tomatoes throughout the summer, instead of all at once, you may want to lean towards indeterminate tomatoes.
If regular tomatoes are typically too acidic for you, there are a number of varieties that are low acid. Look for the gold, orange and yellow tomatoes in all sizes.
If you want fantastic flavour, look to the heirlooms. There is a reason people have been growing them since the 1930s and it's not because they ship well, it's because they taste great!
What do you have or are willing to purchase for plant supports? Most tomatoes will need some sort of support and indeterminate tomatoes need something especially tall.
There are many varieties that are perfect for containers. They are usually determinate and very compact. Often they will have the word "patio" in their name or description.
If you want to save seeds to grow tomatoes next year, be sure to choose open pollinated varieties so that any tomatoes grown from the seeds are the same as their parents.
Last, but not least, make sure to try something new every once in a while! How about a striped zebra type? Maybe a purple or white or black tomato? How about one that has a slight pineapple flavour? There are so many exciting varieties to try!
Tomatoes that work well in Calgary's climate
Cherry Tomatoes:
Tumbler - determinate
Gardeners Delight - indeterminate
Sun-gold - heirloom, indeterminate
Supersweet 100 - indeterminate
Sweet Million - indeterminate
Yellow Pear - heirloom, indeterminate
Medium Sized Tomatoes
Black Krim - heirloom, indeterminate
Champion - determinate
Early Girl - indeterminate
Early Cascade - determinate
Green Zebra - heirloom, indeterminate
Health Kick - determinate
Lemon Boy - determinate
Manitoba - determinate
Pink Ponderosa - heirloom, indeterminate
Slicing Tomatoes (larger-size)
Beefsteak - indeterminate
Bush Beefsteak - determinate
Celebrity - semi-determinate
Cherokee Purple - heirloom, indeterminate
Mortgage Lifter - heirloom, indeterminate
Red or Pink Brandywine - heirloom, indeterminate
Striped German - heirloom, indeterminate
Supersonic - determinate
Paste/Roma Tomatoes
Amish Paste - heirloom, indeterminate
New Jersey Giant - heirloom, indeterminate
Purple Russian - heirloom, indeterminate
Roma - determinate
San Marzano - heirloom, indeterminate
How to Plant Your Tomatoes
The article Transitioning Transplants To The Garden goes over the basics of getting our starter plants into the great outdoors. However, tomatoes do have a few special things we need to consider.
Plant them deep!
Tomatoes are unique in the vegetable world in that you can (and should) plant them deep. The stems of tomatoes, when submerged in soil, will form roots. This is a good thing! It means a larger root system, which provides more water and nutrients to the rest of the plant. More roots also provide more stability so your tall plants don't tip over. When we plant, we want to ensure the plant is deep enough that the new soil level is just below the bottom set of leaves. This also goes for potting up our tomatoes (transferring starter plants into larger containers when they outgrow their current container).
Support
All tomatoes will need some sort of support. Lots of fruit on our plants, coupled with fragile stems and wind means they need some help to keep them from breaking. We don't want to lose our entire crop to a single windy rainstorm! Determinate (bush) tomatoes are easily handled by standard tomato cages or rings. After planting, gently slide the cage over the plant and push it firmly into the soil. Be sure to carefully lift branches up and over as you go so they don't break. They are fragile! You can also build your own teepee type support using any poles or long sticks you have lying around and soft ties to attach stems to the poles.
Indeterminate (vine) tomatoes are a different story. They get tall. Many home gardeners shy away from indeterminate tomatoes because supporting something that tall can be intimidating. How do you support something that may get 8 to 10 feet tall? Tomato cages just won't cut it for vine tomatoes. Here are a couple of different options that work well:
Joe Gardener is a big proponent of tall cages made from cattle panels. Here is the link, including a video how to.
The Florida weave is another popular method (sounds like a line dance, doesn't it?). This is an effective method for high wind areas as it holds the stems quite firmly in place. However, it does require adding additional string as the plants grow, which means some vigilance is required. Garden Betty has good instructions here.
String training is my personal favourite and what I use every year. It involves twirling one main stem around a vertical string to support the tomato. The string is anchored at the soil level and tied directly above the base to a horizontal piece. As the vine grows, it is gently twisted around the string and kept pruned to one main stem, no ties required. This allows for more closely spaced plants and larger, earlier ripening fruit. For information on constructing my metal supports for string training, please refer to the article A Practical Guide To Raised Beds.
Feeding
Tomatoes need quite a bit of water in order to produce big, juicy fruit. Be prepared to consistently get the hose out or set up an irrigation system (a drip system is most efficient). You can also help reduce your watering needs by mulching well around your plants. This reduces water evaporation and keeps the soil a bit cooler. That means less watering for you.
Tomatoes are also heavy feeders. They really appreciate a good helping of compost before planting and a top up mid season as well. I like to to top my future tomato beds with compost the fall before the tomatoes go in so that it has a chance to work it's way down into the soil over the winter and spring.
Containers need a more aggressive feeding schedule as they don't have deep soil and bedrock to draw nutrients from. Compost tea, fish emulsion, kelp or seaweed based fertilizers and/or worm castings are all organic options for feeding your container grown tomatoes. If you are okay with non-organic methods, a water soluble tomato or fruit specific fertilizer (10-52-10 formula) added each time you water will help boost your plants growth and fruit output. Read and follow the instructions on the package for the correct amounts. Too much fertilizer will harm rather than help.
Companion Plants
We can help out our tomato plants and reduce our own workload by adding helper plants around our tomatoes. Some common companion plants for tomatoes include:
Marigolds which attract pollinators (there are no tomatoes without pollination) and also deter many pests (such as whitefly and nematodes) with their smell. French marigolds (Tagetes) also have edible flowers. The lemon ones are my personal favorites and are easy to gather seed from each year.
Tansy discourages cutworms.
Garlic and onions deter aphids and whiteflies with sulphur compounds found in the bulbs and leaves.
Nasturtium attracts pollinators and is a trap crop for aphids. Many varieties are a ground cover, adding additional value by providing cover for beneficial beetles and spiders as well as blocking weed growth.
Basil has been proven to improve the taste and yield of tomatoes when planted close by. Plus we get fresh basil. Win-win.
Just as there are plants that are beneficial to grow with tomatoes, there are a few that can hinder growth. Corn can attract pests that are specific to tomatoes and kohlrabi grown in close proximity is known to stunt tomato growth. In addition, walnut trees produce juglone which inhibits the growth of many plants, including tomatoes. Tomatoes enjoy a fairly acidic soil (5.5 - 6.5) so it is best not to plant them with things that enjoy a more alkaline soil such as the brassicas and dill.
Maintenance
Once tomatoes are growing well, the biggest maintenance task is watering. Ensure your plants have consistent moisture to guard against cracking and to ensure maximum growth.
Pruning
Pruning sounds like a big job, but if you keep up with it can be just a few minutes as you stroll through your vegetable garden. Indeterminate tomatoes require the most pruning to keep them from getting out of control. To keep them to one main stem, you must remove the suckers. These are additional branches that grow in the crotch of the main stem and a branch. Simply snap them with your fingers or snip them with pruners if they are a bit bigger. Removing suckers also allows the plant to concentrate its energy on fruit production. Flowers and fruit will form from shoots off the main stem. If you have the room, you can allow the lowest sucker on the main stem to grow into a secondary main stem and use a string or long pole to support it. Kind of like two plants in one. Many people also trim off all the branches below the first flower cluster. I don't usually bother unless they are interfering with vegetables growing below.
Indeterminate plants should also be topped off at around 3 weeks before our first frost, usually around mid-August. To do this, simply trim off the top of the plant just above the top-most cluster of fruit. Any blossoms that form after this will not have enough time to develop and mature. By topping the plant, we direct its energy to ripening the fruit already underway instead of further plant growth.
A quick tip: if for some reason the top of the main stem breaks off (dogs, kids, storm, etc), you can allow the top most sucker to become the new main stem. Gently direct the sucker upwards and start to twist it around your string or other support, allowing the remains of the broken stem to become a side branch instead.
Determinate tomatoes require little, if any, pruning. I do occasionally trim a few branches back to the main stem if the plant is getting very dense. This helps the sun and airflow reach the inside of the plant to assist with ripening. As with indeterminate tomatoes, remove any flower clusters around mid-August to encourage ripening of existing fruit.
Potential Problems
Blossom end rot
A calcium deficiency in the soil resulting in dark, leathery areas on the blossom end of the fruit. A tomato specific fertilizer (which has added calcium) or ground up egg shells can be added to the soil to help. I add all my egg shells to my compost and use this in my tomato growing beds and I have not had a problem with blossom end rot since. Keep in mind, that if your soil is quite acidic or alkaline (common in Calgary) calcium will be less available to your plants. It may be there, just not in a form your plants can use. Adjusting your soil pH to a more neutral level will solve the problem, adding more calcium will not. (By the way, this is typical of many mineral deficiencies in the soil, so always check your pH.) You can still eat tomatoes with blossom end rot, they are just not as pretty. Simply cut off the offending patch.
Cracking
This commonly occurs when tomatoes are not consistently watered. When a large amount of water is suddenly available to thirsty tomatoes, the skins cannot stretch quickly enough to accommodate the uptake of water, and bingo: cracks.
Sunscald
If you see white patches on the sides of your tomatoes and we have had a scorcher year, your tomatoes most likely have sunscald. It doesn't happen very often in our climate, but it can be mitigated by shading your plants with shade cloth or reducing your pruning to allow leaves to shade the fruit a bit more.
Catfacing
This is when your tomatoes have holes or scars on their blossom end. It is purely cosmetic and not a big deal if you are okay with slightly funny looking tomatoes. They will still taste amazing. It may be caused by blossom damage, low temperatures, high nitrogen levels or herbicide exposure. Plant scientists are still working on it.
Herbicide Injury
Tomatoes are especially sensitive to herbicides. Leaves may become curled and brown, fruit may become irregularly shaped or your plants my just not survive. Even grass clippings that have been exposed to weed killer and used as mulch around your tomatoes will have an impact. Bottom line: don't use them anywhere near your vegetables, and preferably don't use them at all.
Cut worms
These are green little caterpillars that like to munch on young tomato, pepper and brassica transplants that are freshly put into the garden. New plants will have a broken/chewed stem right around the soil line. With the main stem completely severed through, the plant topples over and dies. If there is any chance you have them in your garden, slip a washed tin can or a plastic container (with top and bottom removed) over the top of your plant and press into the ground a couple of inches. This protective ring will prevent the caterpillars from getting to the stems. Those large cans of coffee grounds are perfect for especially large tomato plants. No nasty chemical needed.
Tomato hornworm
Although they are very cool looking
caterpillars (and turn into very cool looking sphinx moths) these guys can do a fair amount damage to your tomatoes. Hand picking is one of the best options. They are a tomato stem green, so you do need to look closely. Hornworm eggs, larva and small caterpillars are also predated on by ladybugs, parasitic wasps and green lacewing larva. So let mother nature help you out by encouraging beneficial insects and not using pesticides in your garden.
Harvesting
Indeterminate tomatoes can be continually picked throughout the summer as each one ripens. For determinate tomatoes, you will have to wait until a bit later when they are all ripe and then do a mass picking. You can tell tomatoes are ripe when they have fully reached the colour they are meant to be. It helps to have a picture of the variety you are growing for comparison. Tomatoes develop their optimum flavor, nutrition, and color when the tomato is in the full red (or orange, purple, black or light green) ripe stage so it is best to pick them off the plant once they have reached that stage. All you need to do is gently twist the tomato until it pulls away from the stem.
Unfortunately, we don't always have a long enough summer to fully ripen each and every tomato on the plant. Fortunately, tomatoes are one of those fruits that will also ripen off the plant. This is really good news for those of us in colder climates. And also for those of us who often get early fall frosts. Yep, I'm talking about you Calgary. If we are only getting a night of mild frost, covering your tomatoes is an option. I use old bed sheets for this, but you can also purchase specific frost cloth from your local gardening center. It is time to get out there and pick them all if:
we are going to get a hard frost (ground frozen solid, not just frost on car windows and grass),
a light frost that is going to last more than a few days, or
we are in for a huge dump of snow that will stick around for a few days.
Pull out some empty cardboard boxes, plastic bins or whatever you have handy and start picking! There have been a few times where I have been outside with the first snow beginning to fall at 9pm at night in my pajamas, desperately cutting down tomato plants and chucking them into boxes to bring inside. I am pretty sure I am not the only one to have done this. As fall nears, keep checking the weather forecast so you don't end up like me. Every year I have a least a few tomatoes that need to be picked while still green. Welcome to cold climate gardening. Once you have them inside, put aside the ripe tomatoes to eat right away and lay out the still green ones in a cool, dark place to ripen. I like to use my furnace room. It is dark and there is lots of floor space to lay them all out. Make sure they are on cardboard or newspaper and that they are in a single layer. More spaced out is better than crowded, if you can. Every few days, take a peak and pull out any that are ripe, disposing of any that are fuzzy or rotten. Tomatoes ripened indoors that were still fully green when picked won't have quite the same flavour as tomatoes pick fully ripe or at the breaker stage (half green and half red) but they are still better than store bought tomatoes!
Keep ripe tomatoes on the counter, not in the refrigerator (they will lose flavour in there). If you are ever overloaded with more tomatoes than you can possibly eat before they go bad, and you don't have time to make sauce or preserve them, throw them whole into a freezer bag and chuck them in the freezer. When you have time, like in the middle of winter, pull them out and make sauce out of them. No loss in flavour or texture that way. Bonus: it's also really easy to pull off the skins after they have been frozen and thawed.
Seed saving
Tomatoes are one of the easiest seeds to save and they are also one of the most expensive seeds to buy. So why aren't you saving your own tomato seeds?
Tomato flowers are considered perfect flowers. That means they have both male and female parts in each flower and they self-pollinate (kind of like plant inbreeding). What that means for you, is that you don't have to worry about keeping different varieties separate to keep them from cross pollinating. As long as your variety is open-pollinated, the seeds you collect will grow into the exact same tomato. The rare potato leaved varieties (very old heirlooms and wild types) are a slight exception. Keep them 5m apart from other varieties if you want to collect their seeds.
I like to use the fermentation method as it is the easiest way to remove the jelly-like membrane around the seeds. Plus, it prevents the transmission of many tomato diseases. Seeds gathered and stored this way will last 4-10 years before losing viability. Here's what you need to do:
Start with fully ripe tomatoes.
Scoop the seeds and pulp into a container with a good fitting lid (don't forget to label with the variety name!).
Let sit on your counter for 3-5 days. Tell your family what you are doing so they don't throw it out.
When the seeds have sunk to the bottom, they are ready. They will also start to be a bit smelly. Another reason to let your family know what you are up to.
Gently pour off the liquid and pulp while retaining the seeds at the bottom. A few seeds may float and get poured off. That is okay, they are most likely hollow duds.
Add a bit of water, stir and let the seeds sink back to the bottom. Carefully pour off the liquid and pulp again. Repeat until water is clear and the seeds are clean.
Drain well in a fine sieve.
Let the seeds dry on a clean plate or tray (they will stick to paper towel so don't use that). Stir them gently with your fingers when half dry to keep them from sticking together.
Once fully dry, store them in an airtight container or paper envelope. Don't forget to label! That's it! Pretty easy right?
Well, that was a lot of information on tomatoes! Thanks for powering through to the end. I know it can be overwhelming, but start with just one or two plants and I promise you will be hooked. Although they can be challenging, especially in our climate, the taste of garden fresh tomatoes more than makes up for the work and worry. Once you have popped a tomato straight from the vine into your mouth, there will be no going back.
Yummy gardening everyone!
Recipes
Basic Tomato Sauce (recipe coming soon)
Pork and Orzo with Spinach (and cherry tomatoes)
Don't forget a good old BLT with garden fresh tomatoes!
or straight up fresh sliced tomatoes with a sprinkle of good sea salt.
Further Information
Casey's Heirloom Tomatoes Airdrie (http://caseysheirloomtomatoes.ca/) source for seeds and starter plants that have been grown and gathered right here in the Calgary area. Information on each and every variety in his catalog.
West Coast Seeds (www.westcoastseeds.com) for everything seed starting, seed sales and timing charts, etc.
Veseys Seeds (https://www.veseys.com/ca/) for seeds, tools, frost cloth and lots of support options.
T & T Seeds (https://ttseeds.com/) Longstanding Manitoba company with a huge variety of seeds as well as trees, shrubs, perennials and gardening accessories.
Johnny’s Seeds (www.johnnyseeds.com) for everything seed starting, seed sales and gardening tools. Note this is an American company so climate information will be potentially different from yours.
Baker Creek Heirloom Seeds (https://www.rareseeds.com/) for specialty and hard to find heirloom seeds. Note this is an American company check hardiness zones and days to maturity before selecting seeds.
Stacey Murphy (https://www.youtube.com/channel/UCK8WWphD0zYS4c5jsLOOOmg) for lots of videos on everything to do with growing food.
"The Joe Gardener Show" (https://joegardener.com/) A plethora of gardening online courses, videos, podcasts and articles.
Lee Valley Tools (https://www.leevalley.com/en-ca) for supports, tools and gardening books.
Lowenfels, Jeff "Teaming with Nutrients" 2013, Timber Press Inc., Portland, OR, USA
Seeds of Diversity Canada "How to Save Your Own Seeds" 2013, Waterloo, ON, Canada (for tomato specifics: https://www.seeds.ca/d/?n=seedlibrary/community/how_to_save_tomato_handout.pdf)
Ulager, Jim "Beginning Seed Saving for the Home Gardener" 2019, New Society Publishers, Gabriola Island, BC, Canada