Updated: Apr 15, 2021
Growing these most luscious and voluptuous of fruits (yes, fruits) from seeds or from seedlings is easier than you think.
The mass migration toward all things gardening and homegrown has inspired a virtual avalanche of how-to advice for budding tomato growers. While truly awesome in principle, the sheer volume of information can be daunting, even for green thumbs.
The truth is, for me at least, there are few hard and fast rules that I follow, and 'knock on wood', my tomato babies grow up big and strong, year after year. I am happy to share those with you now because quite frankly, there are few garden victories sweeter than homegrown tomatoes.
If you are new to gardening and want to hedge your bets, my advice would be to buy a few small, healthy tomato seedlings (plants) from a reputable source, as well as start plants from seed (indoors or outdoors, depending on your planting zone and time of year). Seedlings are tangible plant babies that have already done the hard work of birthing, hardening off, and growing to manageable size. Growing from seed however, will create a tomato intimacy from which there is no turning back.
Where I live in the Pacific Northwest, in zone 7B, the recommended time for planting tomato plants in the ground or in pots outdoors is in June, once the soil and air temperatures and humidity levels are favourable. Don't guess on when the time is right where you live; ask your garden centre or a gardener friend for advice.
I have a few tomato-friendly microclimates in my garden, and we inherited a small old but intact greenhouse, so I am able to start tomato season early, and finish late. For years that wasn't the case, and like millions of other home gardeners, I kept it simple and just dug in.
Keeping it simple is easier with a basic understanding of tomato growing language. There are always exceptions to classifications, definitions, and rules, and for sure you should explore those. By and large however, I find these simple generalizations, tomato trivia, and memory tricks helpful for me. I hope they help you too:
Inderterminate (undecided) tomatoes - don't know when to stop growing up and sideways. They almost always require or benefit from support of some kind (stake, string, trellis, cage, etc), are often but not always 'vining type', they benefit from pruning or pinching to control their growth and direct energy to fruit production, and they produce fruit consistently or in batches over time, from maturity until death. Fruit size and plant size are not indicators of indeterminate or determinate classification: Beefsteak (big fruit), Early Girl (mid size fruit), Sungold (cherry size fruit), and tiny wild currant tomatoes (pea size fruit) are all indeterminate, yet their characteristics vary considerably.
Determinate (decided) tomatoes - grow to a particular size, and typically produce fruit on a more voluminous plant all at once, or within a predictable period of time. They generally require some form of support like a tomato cage or stakes. Popular varieties Supremo Roma (large size fruit), Paisano San Marzano (medium/large size fruit), Oregon Spring (medium size fruit), Patio Choice Yellow (cherry size fruit), and Tiny Tim (miniature cherry size fruit) are all determinate, yet their characteristics vary considerably.
Semi-determinate tomatoes - as the name implies, these beauties exhibit any combination of characteristics unique to determinate and/or indeterminate tomatoes. There are no absolutes, but very often semis are indeterminates with slower or stunted growth habits which create bushier or fuller plants requiring less maintenance or management.
Plant breeders designing for batch volume and small space efficiency often create semi-determinate tomato varieties. An example of a purpose-built semi-determinate tomato is the highly-nutritious, spectacularly beautiful Midnight Roma, purple and blood red paste tomato, designed by Oregon State University breeder Dr. Jim Myers. I am growing these lovelies from seed, under lights in my home office at this very moment, and cannot wait to plant them out. Homegrown tomato geek that I am, I will very likely plan a wine-paired culinary event to celebrate the harvest.
Vining tomatoes - indeterminate tomatoes that grow and grow up a trellis, string, stake, or even along the ground like a sprawling zucchini. Tiny hairs along the stalk of the plant will 'root' into soil on contact (not suited to most North American garden climates). Sungold (cherry size fruit), Sweet Million (cherry size fruit), Early Girl (medium size fruit), are examples of vining tomatoes. A hand-harvestable height of six or seven feet is typical, but I grow my vining tomatoes to a height of 10+ feet under our glass patio cover, and use a small stepladder to harvest the last (highest) fruit to ripen.
Bush tomatoes - typically but not always determinate or semi-determinate foliage-heavy varieties of tomatoes that grow to less than five feet in height and produce earlier in the season than most other tomatoes. Dwarf bush tomatoes like Tiny Tim and Tumbler produce masses of cherry tomatoes in a relatively small amount of real estate and are perfectly suited for pots and hanging baskets.
If you're thinking that vining and interderminate tomato language is somewhat interchangeable, you are right - as is bush and determinate. It's simple, really.
One more delicious tidbit to remember is that tomatoes are self-pollinating, which means that tomato flowers each have the requisite female and male equipment on board, to turn blossoms into tomato babies, and under most circumstances can do so without relying on bees and other pollinators to do the deed.
Typically, the natural movement of air caused by wind, animals, insects and people moving in and around where tomato plants grow outdoors, will facilitate pollination and subsequent setting of fruit. One should then, move tomato seedlings outdoors, protected if necessary, before they flower or shortly thereafter. I have had tomato plants in my greenhouse set fruit however, so clearly the amount of air disturbance required to mix things up, is minimal.
Now back to the garden, or to the grow lights. If you are starting tomatoes from seed, you will want to do so 6-8 weeks before the estimated last front date in your area. A simple Google search will tell you when that is. Gardening experts recommend using a sterile soil-less seed-starting mix and no fertilizer. I don't dispute that this works as I have done it myself, but I have had excellent success with organic compost supplemented with 20% worm castings (poop) also.
The benefit of using a sterile mix is to prevent the import of any soil-borne pathogens, fungi, or insect eggs, from finding their way into the mix and destroying the entire crop. If you are using garden soil or soil of questionable lineage, there is a very good chance this will happen.
So, unless you can access organic compost and are sure that it is clean, you may be best advised to use a sterile mix. Also, I have found that seed starting outdoors is more forgiving than seed starting indoors, perhaps because pests and fungi have a greater choice of vegetation to go after.
I use a heat mat set under my seed tray, to warm the soil to 75F, to encourage early and uniform germination of tomato seeds. A heat mat is not necessary however, as a sunny windowsill, or a warm spot atop a fridge or other appliance, does nicely as well. Moist but not wet soil (like moist chocolate cake), and a humidity dome or simple plastic wrap, will help keep the growing medium and the seeds moist until germination.
Artificial or natural sunlight are not necessary up until the time the tomato seeds germinate, but once they do, the tiny plants will need up to 16 hours of light per day (depending on type of light source). Because my seed starting set-up is in my home office, and the lights are too bright to sit next to, I run the 'daylight' hours through the night, when I am not at my desk.
There are all sorts of recommendations about how close grow lights should be to tomato seedlings, but really it depends on the sort of light you are using, and the variety of tomatoes you are growing. If the leaves turn red/purple and become crisp and curly/crinkly it is likely as sign that they are getting too much light or are too close to the light. The leaves may also become pale and sunburned. Through observation you will learn enough to assess the situation, so simply follow your instincts in response to these things, and adjust the light accordingly.
Tomato seeds started over a heat mat or other source of heat, typically start germinating as a group, in three or four days. Unheated seeds can take twice or longer to germinate, and they will pop through a few at a time over several days. Either way, once a critical mass of seeds have germinated, it is time to remove the humidity dome or plastic, and begin a schedule of growth, rest, and consistent watering.
Take care to not over-water tomato seedlings, as they can "dampen off' (rot at soil level) and die. There is no cure for this, only prevention. Running a small fan on a very low speed (think gentle breeze), some distance from the seedlings will definitely help prevent damping off. Don't worry about the cold air hurting the seedlings. Once they have germinated, heat plays a much smaller role.
The first set of tiny leaves that appear on either side of the slender stem are called cotyledons, and they are the leaves of the seed embryo, they are not actually 'true leaves'. True tomato leaves are discernibly different in presentation, and they come next. Their appearance in full glory, is a sign that the seedlings can be transplanted safely.
Many gardeners multi-sow hundreds of tomato seeds in large 10"x20" seed trays, or they sow the contents of an entire seed packet in one 4"x4" pot or cell. The seedlings are then thinned by removing and discarding the smaller plants and transplanting the larger ones, or by snipping smaller plants to soil level (and discarding the tops), leaving the bigger and stronger seedlings to grow to capacity.
I understand why this is done, but I don't do it. I hate waste of any kind, and if I buy a packet of 20 heirloom seeds, I plant one seed in each cell of 20 individual modules, in a 72 cell tray, or 4-6 evenly spaced seeds in a small 2"x4" cell insert. I find that the plants are healthier and stronger by giving them their own space at the outset, and that germination percentage rates are higher. You should do what works for you.
Plants can be transplanted when the first set of true leaves is set, but because I sow seeds individually, waiting on the second set of true leaves seems to benefit the plant. Subsequent transplantings or 'potting on' should be done when the seedlings grow to a height that is three times the width of the pot they are in. That is a general potting on rule, not a hard and fast one.
Also, generally during potting on, assess the full height of the plant, remove all leaves on the lower 2/3, and bury the entire stalk in a deeper pot, to that level. As if by magic, the thousands of tiny hairs along the length of the stalk will soon 'take root' in the soil or starting medium, start absorbing nutrients and making friends with mycelial networks, and help your tomato babies grow big and strong. This stalk burying and rooting characteristic is unique to tomatoes, so don't assume you can do it with all plants.
The potting on rule of thumb is a good one to follow with purchased tomato seedlings as well, up until and including the time you plant them in living soil, in the garden or in containers. Once planted in their forever home, do not uproot the plants or otherwise disturb the root structure. The invisible but highly complex and sophisticated underground network created in the root zone (rhizoshpere), between the tomato roots, beneficial and sympathetic mycelium/'fungi roots' (not exactly, but it works for illustrative purposes), and microorganisms, creates a delicious recipe for healthy soil biology which ultimately leads to tomato health and happiness. That is, if we let it. So let's let it. Don't dig about and disrupt the network.
Tomato plants grown in depleted or manufactured soil often benefit from the application of natural sourced phosphorus, and also, access to calcium. Phosphorous helps build strong roots and cell structure, and calcium helps prevent blossom end rot. Several organic options exist, and though I have no experience with any of them, friends do swear by rock phosphate as a soil amendment during final planting, as a sort of slow release provider of minerals.
I use 100% pure worm castings at a rate of 20% as an all-around organic fertilizer, in the organic compost that I use as a potting on medium. Worm composts in each of our raised beds, supply worm casting fertilizer to all fruits and vegetables throughout the year as well. I've never analyzed the poop, but my plants are happy and productive, with lush foliage and robust root structure.
My final bit of advice relates to tomato plant maintenance and trellising. I grow indeterminate tomatoes up string trellises anchored in large planters, and attached to the rafters of our glass patio cover. I attach the central stem loosely to the string with green velcro tape that I recycle season after season. I underplant with several varieties of basil, which not only helps deter pests, but pairs perfectly with vine ripened tomatoes.
Also, I pinch the side shoots of indeterminate tomatoes (and sometimes leggy determinate plants), forcing them the concentrate their energy on fruiting and on growing straight up, rather than on foliage and lateral expansion. Side shoots are those wanabee branches that appear regularly in crotches between the vertical stalk and the horizontal branches that grow from it. Pinching side shoots helps ensure adequate air circulation and access to sunlight within and between the plants columns.
The side shoots grow out at a 45-degree angle and are easy to spot. A simple pinch will take them out. Sometimes I let these shoots grow to six inches or so in length before I pinch or snip them, and then I set them in a jar of clean water (out of direct sunlight) until the tiny hairs on the stalk become roots. These new plants can then go straight into soil -- instant tomato plant.
This season I started several varieties of tomatoes from seed, indoors. Most are outside now, in our small greenhouse which is unheated during the day, but kept above 40F at night. This weekend I will be potting on like mad, sharing plants with friends and neighbours.
My 2021 tomato menu includes:
Tumbler red cherry, determinate bush type.
Tiny Tim red cherry, determinate dwarf bush type
Gardener's Delight red cherry, indeterminate vining type
Sungold orange cherry, indeterminate vining type
Golden Rave two-bite yellow cherry, indeterminate vining type
Early Cascade, medium size red, indeterminate vining type
Early Girl, medium size red, indeterminate vining type
Green Zebra, medium size green, indeterminate vining type
Tasmanian Chocolate, medium size red/brown, determinate bush type
Inca Jewels, medium size red paste, determinate bush type
Midnight Roma, medium size purple paste, semi-determinate
The small bush type tomatoes and for experimentation in hanging baskets, and also for friends and clients with container gardens. The Sungolds and Gardener's Delight are staples of our covered tomato garden (microclimate and heat sink) that produces through mid November, and I've grown many extra plants for friends. These two workhorse varieties, plus the Early Girls and Cascades will be enjoyed fresh daily through the season, but most will be oven-dried in a bit of confit garlic oil and sea salt, then frozen in 8-oz containers for use throughout the winter.
The Tasmanian Chocolate and Inca Jewels tomatoes were designed for high-yield container growing, and will be trialed in the container gardens of friends and family. Both of these varieties were rather fussy and somewhat hesitant under LED light, but did very well just as soon as they moved outside into natural light.
I am not sure yet about the Green Zebras and the Golden Raves, as these are new to me, but for sure I will experiment with ways to present, cook and preserve them, finding and celebrating the qualities that are unique to them.
The Midnight Romas are the big tomato deal of the season for me. I cannot wait to see them, more excited still to try them. These beauties are in my book, the sexiest and most perfect of tomatoes. I hope they taste half as good as they look.
All of these tomatoes are good for you. Tomatoes are perhaps best known as being a major dietary source of the antioxidant lycopene, which studies show reduces risk of cancer and heart disease. In spite of containing 95% water on average, tomatoes are a good source of vitamins and minerals, and an excellent source of insoluble fibre.
According to the online resource Healthline, a raw tomato contains:
Vitamin C. This vitamin is an essential nutrient and antioxidant. One medium-sized tomato can provide about 28% of the Reference Daily Intake (RDI).
Potassium. An essential mineral, potassium is beneficial for blood pressure control and heart disease prevention.
Vitamin K1. Also known as phylloquinone, vitamin K is important for blood clotting and bone health.
Folate (vitamin B9). One of the B vitamins, folate is important for normal tissue growth and cell function. It’s particularly important for pregnant women.
Ways to enjoy homegrown tomatoes:
Fresh, right out of the garden. Best enjoyed still warm from the sun.
Sliced, in a gorgeous Caprese salad together with torn fresh freckled basil leaves, fresh mozzarella, curd, or burrata cheese, extra virgin olive oil and balsamic vinegar.
Oven dried. Cut cherry tomatoes in half, and larger tomatoes into quarters or eighths, toss in confit garlic oil (or regular olive oil), and a pinch each of sea salt and red pepper flakes. Spread tomatoes on a parchment lined baking sheet and dry slowly in a 275-300F oven, for up to several hours until almost dehydrated but still somewhat squishy and soft. Cool and then freeze in 8-oz containers. Use throughout the year whole or diced in pasta sauces, bruschetta, on pizza, on fresh bread, etc.
Wash dry and freeze tomatoes whole, in airtight containers, for use later in soups, sauces, just about anything cooked that you would use fresh tomatoes for. Toss a handful of frozen cherry tomatoes in a few tablespoons of olive oil, with a clove of garlic (minced), and chopped fresh herbs to taste, over low heat in a saute pan. Cook through until 'melted' and toss into fresh hot or cold pasta noodles. Use thawed whole large tomatoes as you would canned tomatoes.
Peel and preserve paste type tomatoes whole or halved in glass jars, or first remove the skins and seeds and preserve just the passata.
Harvest an entire stem of almost ripe cherry tomatoes, and grill them as-is on the barbeque or in a cast iron pan, until slightly charred. Serve with fish or chicken, or on a cheese and charcuterie board.
Make fresh salsa by dicing multi coloured tomatoes, red onion, cilantro, jalapeno pepper, add fresh lime juice to taste and season with salt and pepper.
Lacto-ferment green tomatoes at the end of the season in a 2% brine solution (19grams of sea salt per 1 quart filtered water). Fermented foods are good for our gut health.
Make tomato tinted pesto by replacing 25% of a traditional green with oven-dried tomato.
Make a quick summer gazpacho by combining two large paste tomatoes (cored), one small cucumber, one small bell pepper (seeded), a half-dozen radishes, one clove garlic and one shallot (peeled), one small handful dill or fennel fronds, two tablespoons each olive oil and red wine vinegar, sea salt and pepper. Process in a blender until smooth. Adjust seasoning. Chill. Serve in small chilled bowls, garnish with chopped herbs and drizzle with fresh lemon or lime juice.
So now that you know a few tomato tips and tricks, you also know that it's not too late to channel your inner gardening intuition and start them from seed. It's easier than you think, and you are a better gardener than you know. Just dig in, and ask for help if you need it.
To learn about urban permaculture and permaculture principles, watch Modern Farmer Magazine's Urban Permaculture video series in which publisher Frank Giustra and I introduce the basics.
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