Guide to Growing Tomatoes: From Seed To Harvest
The more familiar you become with your plants and what they need to thrive, the more
rewarding and productive your garden will be! Below, we’ve shared the basics of
growing amazing Tomatoes; however, much of the information can be applied to
Peppers, Tomatillos and Eggplants, which are also Nightshade vegetables.
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Remember, we all learn a lot through making mistakes; so be sure to leave space for
those too! Lessons learned in the garden expand our knowledge and skills for years to
come. There is no substitute for first hand experience.
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STARTING TOMATO PLANTS FROM SEED
Timing
Start tomatoes from seed indoors 6-8 weeks before your local last frost date. The timing
really matters! If you start them too early, the plants will outgrow the available indoor
light and space before it is warm enough to move them outdoors. With insufficient light,
tomato stems will become weak and leggy. If you start them too late, you could miss the
season, and your fruit may not ripen before Autumn’s first frost.
Potting Mix
Start with the right growing medium. You can go with a regular or organic myco-active
“pro-mix” potting soil. To add a bit of oompf to the potting soil we generally add some
well-rotted manure, kelp powder & worm castings.
CONTAINERS
Your choice of container depends on your preferred method. There are pros and cons
for each type.
Seed Tray with/without cells
A seed tray is fine, but you will need to pot up seedlings into a deeper container as they
grow. Seed trays with individual cells allow for easier control of individual plants. But
having to re-pot them as they grow may disturb roots and hinder growth. If you are
growing LOTS of tomatoes though, this method saves space. Also, seed trays typically
fit perfectly over heat mats.
Plastic plant pots from previous years
This is a great option! Sterilize containers before reusing and make sure they have
holes at the bottom to allow water to drain.
We start our tomato seeds in a bit of potting soil at the bottom of a makeshift pot,
usually a milk carton scored from a local cafe. *Poke holes in bottom of the milk carton!*
As the tomato seedlings grow, we pinch off the lower leaves and add more soil. We
continue this process until the soil level is flush with the top of the pot. This allows for
transplants to develop massive root systems & eliminates the need to repot. You can do
this with milk bags too; just start them out with the sides rolled down and roll them up as
the plants grow and as you add more soil.
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RAISING TOMATO SEEDLINGS
Tomato seedlings will need a fair bit of regular attention as they grow. The most
important things to consider at this stage are light, heat, water and space.
Light
If you don’t have a dedicated space with grow lights, you will need space near a natural
light source. If your tomato plants are not getting adequate light, they will appear leggy,
which means the stems will be long, thin, and reaching towards a light source. Leggy
stems are weak. To mitigate legginess, rotate your trays every few days and consider
having a gentle fan blowing to build up their plant muscles. 💪
Heat
Tomato plants appreciate a little help from heat mats. Tomato seeds can be painfully slow to germinate if they are too cold, but germination times can be sped up with a little heat from beneath!
Nightshades thrive at 20-30ᵒC! If your plants are not getting enough heat, growth will slow or stop altogether and the leaves may turn a purple shade. *It is important to not that plants that produce purple, blue or black tomatoes often have purple tones to their leaves. This is normal for them. *
Watering
Tomato plants need even & regular watering. Many issues can stem from inconsistent
watering - too much or too little.
Signs of overwatering include: Damping-Off Disease (wilting with thin rotting stems),
fungus or mould on the soil surface and yellowing leaves. Damping Off Disease can
also be caused by overly humid conditions and unsterilized containers.
Signs of underwatering include: Weak, wilting plants & shrunken soil. Allowing plants to
wilt can severely stunt their growth! This seems like a no-brainer, but it can happen to
the best of us and it is important to know how to best come out of it. Extremely dry soil
doesn’t hold water, so surface watering doesn’t cut it. Super dry pots/trays must be
soaked, not simply watered, to become re-hydrated.
Space
The final frontier. Once they get going, tomato plants grow quickly, and may outgrow
their space and/or containers before they are ready for the garden. Our milk carton
method is a great way to avoid re-potting. If you do find yourself in a position where
re-potting is unavoidable, remember that every little “hair” on the stem is a baby root.
Place the root mass at the bottom of the new pot and bury the tomato plant up to the
bottom of the newest leaves. *Peppers do not have these rootlets, so don’t bury them!
PESTS
If you are starting your tomatoes in a hoop house, you need to watch out for Cutworms,
Slugs and Mice nibbling your tender plants! Indoor pests to watch for include Aphids
and Spider Mites, which could find their way from your houseplants to your seedlings.
There are some detailed hacks for dealing with ![]()
Tomato pests in our article on Tomato Pests & Diseases.
HARDENING OFF
Ideally, your first day of hardening-off should be overcast & not windy. Bring your plants
outside to a sheltered, shady area for part of the first day, and a bit longer each day that
follows. Slowly increase exposure to direct sun and the elements. After a week of this
routine, your tomato plants are hardened off and if your local frost date has passed, it’s
time to move them into the garden!
HOW TO TRANSPLANT TOMATO SEEDLINGS
You’ll want to plant your tomato plants deeply in the garden. When transplanting aim to bury 1/3 to 1/2 of the stem along with the root ball. So, make sure you dig the hole deep enough. By doing this you will encourage a massive root system! For us, the root is the depth of a milk carton, so we dig our holes to one foot. Think of that root’s ability to expand and to collect water from deep in the Earth, all Summer long!
Leave a bowl-shaped depression around the base of the plant so that water flows down
towards its roots. If you decide to grow tomatoes in pots, choose a large, deep container
to help maintain soil moisture and prepare to water every day.
SUN, SOIL, SPACING AND SUPPORTS ![]()
Sun & Soil
Tomato plants prefer full sun and rich, deeply watered soil. Plenty of compost, manure,
and organic matter will keep your plants going strong. Planting white clover as a living
mulch can also provide valuable nutrients, like nitrogen, and conserve moisture in the
soil.
Spacing
Give your plants enough space! Tomatoes, Peppers, Tomatillos and Eggplants should
all get 18-24 inches of personal space (between plants). Closely spaced, crowded
plants will deplete nutrients, and can create mildew issues. You want air to circulate
freely around each plant to prevent disease and minimize pests. Pruning each plant to
one main trunk can help with airflow and will put all of the plant’s energy into producing
beautiful, juicy fruit! Biologically active soils, with cover cropping or regular inputs of
compost / manure provide all the nutrients tomato plants need to thrive!
Supports
All tomatoes benefit from support. Determinate, or bush tomatoes, do not grow very tall
and require only simple staking. Indeterminate varieties are sprawly and can reach 6-10
feet in height. As they continue to grow, the more fruit they’ll produce. Indeterminate
tomato plants need strong stakes & do best when suckers are actively pruned away.
When considering supports, a good rule of thumb is to always allow for more height
than you expect the plants to need. Also consider, strong, gusty winds that can arrive in
late Summer.
For more on how to care for your tomato plants in the garden, including info on common
tomato diseases, check out The Incredible Guide To Growing Tomatoes: Soil,
SAVING TOMATO SEEDS
Saving seeds from your own garden opens up a whole new level of rewards.
Gathering seeds from your own garden creates genetic resilience for your area’s unique
micro-climate and a more intimate relationship with your plants.♥
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Learn more about seed saving and what you need to consider in The Incredible Guide
