top of page
  • Writer's picture Sophie Jobin

How to Grow: Tomatoes

Updated: Jul 30, 2022


The Tomato is a native of the Peru, Bolivia, and Ecuador area of the Andes Mountains. It wasn't until 1835 that the northeastern United States considered it a suitable food crop. It is related to many crop plants such as potatoes, peppers, and eggplant.

Fruits grow from the flower of a plant and have a single or many seeds inside.

Tomatoes are botanically known as a fruit, even though we all call them vegetables. They grow from small yellow flowers on their beautiful vines and produce loads of seeds, that you can later use to produce more seeds.


Once you've gotten your tomato seeds picked out, purchased and brought home, it's now time to start those seedlings indoors.

When to Plant Tomatoes

Tomatoes are a warm-season vegetables and need a long, hot summer. Start them in late-winter or early spring, For me in zone 6b, I start them around March. Thankfully tomatoes don't take as long to produce as peppers. Depending on the variety, they can take up between 50-80 days to fully fruit and change color. Starting them around March-April will ensure a long enough timeline to get what these amazing plants have to offer.

Determinate versus Indeterminate Tomatoes

Tomatoes fall in to two categories: determinate versus indeterminate.

Determinate Tomatoes:

- Grow in more of a bush form

- They usually stop growing around 3'-4' feet tall.

- Usually supported by a cage.

- When the flowers begin to blossom at the tips of the branches, the plant has reached its full height.

- Plants usually ripen all at once - this type of plant is good for people who like to can tomatoes.

Indeterminate Tomatoes:

- Can grow indefinitely until weather kills it.

- They usually stop growing around 6'-20' feet tall.

- At the beginning they require substantial caging or staking - whether that be a metal or string trellis.

- The plant will ripen all year long until the frost or disease kills the plant.

Starting Seeds Indoors

Depending on your zone, it may be advised to start your seeds indoors rather than in the garden. Here in zone 6b, I start mine around March indoors. Tomatoes are not frost hardy and will die from the cold. Tomatoes germinate and grow quickly, compared to most other crops. They have specific needs:

  • Sow seeds in plug trays or 6 cell trays of soilless mix.

  • A minimum temperature for seed germination is 10°C

  • An optimum temperature range for growth is 17 to 20°C.

  • They should be sown 8 to 10 weeks before transplanting outside. (hence my March start date)

  • Learn how to: Sow seeds

PRO TIP: they are fast to sprout, so don't plant them in the same trays as longer sprouting plants like onions and peppers.

Potting Up

There comes a point when your seedlings become to big for their original pot and need to be potted up.

  • For the first repotting: if you used a seedling tray, first thing is checking out the roots. It's important to have an established root system before transplanting. The plant should ideally be the same height of it's original pot with it's first true leaves showing. Transplant them into a 2"or 4" pot in fertile potting mix or compost soil.

  • For the second repotting: if you are coming from a 2" or 4" pot, the plants should be three times the size of it's original pot. Transplant them into a 6" or 8" pot in fertile potting mix or compost soil.

  • If you desire to keep transplanting one more time - you can. Same rules apply above, pot up to a 12" pot in fertile potting mix or compost soil. It will depend on what zone you are in if the third repotting needs to happen. Some frost dates can go into late May early June! So beware of planting out too soon for your zone.

Planting Your Tomatoes Deeper

Have you ever heard someone tell you to bury your tomatoes deep into the ground? Well here's why. When potting up for your transplants, tomatoes have a unique characteristic you won't see on every plant. They have what is called trichomes, more specifically glandular trichomes, all along the stem of the plant. It's the very short hairs all along the stem of the plant. These trichomes can serve different purposes whether above or below the ground. Below the ground they can actually become roots.

The benefits of trichomes:

- Thicker skin on the plant, the hairs can act as an irritant towards some insects.

- Pest repellent, they actually give off essential oils (hence why tomatoes smell so lovely), the smell can help deter some insects away.

- Help protect plants from ultraviolet light, they help strong sunlight from becoming too much - that doesn't count for the leaves though, they are still vulnerable to sun damage.

- Drought resistant, with all those extra roots means it can absorb more water.

Hardening Off

Before planting your Tomato transplants in the garden, you have harden them off. What does that mean?

Hardening off: is the process of introducing your indoors seedlings to the outdoors gradually. We want to ensure that the outside exposure doesn't wilt your plant, as the exposure can be quite different.

Click here to learn how to: Harden off Plants

Planting Spot or Pot

Planting Spot in the Garden

Being a tropical plant, they like full sun to produce all those beautiful fruits. Pick the warmest spot in your garden to plant them — one where the snow melts first. Trust me, I have tried part-shade part-sun, they didn't grow very much. Lesson learned.

Planting in a Pot

Tomatoes in pots like full sun and the warmest spot in your garden. Tomatoes are big plants so you'll want to use 12"-14" pot per plant. I usually grow 7-8 tomato plants on my back deck no problem, both determinate and indeterminate.

Crop Rotation & Soil Preparation

Soil should be well-draining and rich in organic matter. Before we plant outside, work some aged manure or compost into the soil.

Tomatoes are very heavy feeders — meaning they are hungry plants. If you have grown any brassicas or any nightshade family plants like potatoes, peppers, eggplants or even tomatoes the previous year, avoid planting in the same area again the following year. This will not only help to lessen soil depletion but also help with disease control.

PRO TIP: Introduce some nitrogen rich plants like beans for a season to help replenish the soil.

Staking + Cages

Tomatoes grow the most beautiful fruit, in all shapes and sizes, and it just so happens that the branches will snap off if not supported properly. Like peppers, tomatoes will benefit from being staked or caged.

What I have noticed personally:

Determinate versus Indeterminate: I find they not every single tomato plant will bulk up the same. I have noticed that indeterminate tomatoes are a lot thinner when it comes to their overall stalk, whereas determinants usually have no issues with getting a bulkier stem. Therefore, I end up staking my indeterminate plants more often than determinate even as transplants for that extra support.

Determinate: when it comes time to plant outside, whether that be in the ground or a pot, I always cage them young. As they grow I make sure the branches are placed well along the cage to help with proper support.

Indeterminate: I never cage my indeterminate plants unless I know the tomatoes are more cherry size than grape. You can either stake them, cage them, or both. Another fun way you can grow indeterminates are on a trellis. I don't have enough room yet for such a fancy method but certainly one day I will!

Mulching & Watering

Tomatoes require an adequate and regular supply of water. Being tropical and all, they tend to be very thirsty plants. Like most plants, best advice:

- Moderate supply of water from the moment they sprout until the end of the season.

- Tomatoes DISLIKE wet feet. So waterlogged roots aren't an option, avoid overwatering.

- They need well drained soil, but hold enough moisture to keep the plants alive.

POV: Tomatoes need a lot of water, especially when they are in pots. In my experience, once they outgrow the pot, I personally have to water mine every morning during the summer. The leaves droop when it is dehydrated, so it will let you know when it needs water.

Tomatoes are susceptible to blossom-end rot if not adequately watered.

One way to help maintain moisture and prevent excessive evaporation in the soil is to add mulch or compost at the base of the plant.


Tomatoes respond to a good fertilization program, especially when they start to grow those beautiful fruit.

Two scenarios:

Before transplanting: Apply a 5-10-10 fertilizer in the ground and place soil on top covering enough so the roots don't touch — as it may burn them.

While producing fruit: You can apply a fertilizer when the plant starts to produce fruit. Ensure the plant is well watered and place it at the base of the plant without it touching the stem. This way we can avoid the plant getting burned.

NEVER DO THIS DURING THE DAY, heat will cause undesirable damage and could kill your plant. Preferably fertilize during a rainy day.


Make sure that any perennial weeds be controlled before planting. I advise never to use any herbicides to control weeds, it's not healthy for you nor is it healthy for the planet. If weeds get bad, cultivating and/or hoeing them are advised.


Tomatoes can be harvested whenever they reach the desired size or colour.

  • Tomatoes are harvested when they reach full size, are firm and have a thick flesh.

  • Usually you want to pick them when they changed to their desired colour. Whether that be green, red, orange, yellow, or purple! Check your seed packet for details on that.

Late Season Rain Fall

A good time to harvest your tomatoes are before a big rainstorm in the late season. What can end up happening is if left on the vine to long - they will split. This split happens when the tomato absorbs to much water and breaks open the flesh. You can still eat the tomato, no worries about that, it just won't be one to store on the counter as it will rot a lot faster.

Late Season Frost

If you are still growing some tomatoes all the way into the fall be careful of any frost warnings. If you aren't able to provide shelter for your tomatoes, you can always pick them early while they are still green and let them ripen indoors. A great way to ripen any tomato is to place them in a brown paper bag with an apple. You don't want to put it in a plastic bag - as that doesn't breath and moisture issues can become a problem.

The science behind the apple and tomato: Most people think that you need to let a tomatoes ripen on the vine but it's not always needed. Most fruit, including tomatoes and apples, produce ethylene gas which is helps ripen up the fruit. It just so happens that apples produce a higher amount of ethylene gas more than most - which is why placing them near any other fruit will help ripen them up faster

If you're planting tomatoes this year, I'd love to see it! Tag #jobinkitchengarden on Instagram or on Facebook.

Pin to Pinterest

Recent Posts

See All


bottom of page