Learn how to grow tomatoes from seed to harvest.
There’s nothing quite like biting into a sun-warmed tomato fresh from your own garden. Juicy, sweet, and tangy, and worlds away from anything you’ll find at the grocery store.
A well-grown tomato has the power to convert even confirmed plant haters into gardeners.
In this post, I’ll walk you through every step of growing tomatoes from seed to harvest. We’ll cover when to start tomato seeds, how to care for seedlings, the best transplanting techniques, and I’ll share a few tricks to grow the most flavorful tomatoes you’ve ever tasted.
If you’re new to growing tomatoes (and even if you’re not!), I’m glad you’re here, and I can’t wait for you to grow your own.
Table of Contents
- Why Grow Tomatoes from Seed?
- Choosing Your Tomato Varieties
- Starting Tomatoes from Seed (the Cliff Notes)
- Caring for Seedlings
- Potting Up Seedlings
- Hardening Off
- Transplanting into the Garden
- Ongoing Care
- Supporting Your Tomatoes
- Tricks for the Best-Tasting Tomatoes
- Troubleshooting Common Problems
- Harvesting Your Tomatoes
Why Grow Tomatoes From Seed?
Starting tomatoes from seed gives you access to hundreds of varieties you’ll never find at the nursery. Heirlooms like Cherokee Purple and Brandywine, sugar-sweet cherry tomatoes like Sun Gold, and other unique varieties bred for flavor, hardiness, and special growing conditions.
I like starting tomatoes from seed as well because I can be in control of the process and time my plants to be just the right size for planting in my garden.
Plus it’s just a special feeling picking a ripe tomato from a plant you’ve been caring for since it was a tiny seed. If you have kids, then you know what I mean!
Affiliate Disclosure: This post contains affiliate links. By purchasing through my links, I may earn a small commission at no extra cost to you.
Choosing Your Tomato Varieties
Before you start seeds, you need to know a bit about the two main types of tomatoes:
- Determinate Tomatoes: grow to a set height (usually 3-4 feet), produce fruit all at once over a few weeks, then stop. Great for sauce or salsa or for small space gardens. Sometimes labeled “bush” tomatoes. Do not prune.
- Indeterminate Tomatoes: grow and produce fruit continuously until frost. Most heirloom tomatoes are indeterminate. They’ll get tall and need support, but you’ll have tomatoes all season long. Can be pruned.
From there, tomatoes are separated by color and also by type: salad, paste, slicer.
For a deep dive into which tomato best fits your needs, read my post on choosing the best tomato varieties for your garden.
My Favorite Seed Companies
These companies carry many different tomato seeds and will explain more about the varieties. Have fun browsing!
- Botanical Interests
- High Mowing Organic Seeds
- Pinetree Garden Seeds
- Baker Creek Heirloom Seeds
- Johnny’s Selected Seeds
- MIgardener
- Quail Seeds
Starting Tomatoes from Seed (the Cliff Notes)
Once you’ve picked out your different tomato varieties, you may be wondering when to grow tomatoes from seed.
Tomatoes grow fast, but take a while to produce.
Starting tomato plants indoors rather than planting seeds outdoors will give you healthy, robust tomato-making machines sooner and at just the right time.
Plus, you’ll get to brag to anyone in earshot, “I grew this from seed!”
When to Start Tomato Seeds
Start seeds indoors about 6 weeks before your last frost date.
I find 6 weeks to be the sweet spot.
Starting too early means more potting up plus longer intensive care, and you may wind up with root-bound plants that struggle after transplanting. But starting too late means you’ll miss out on early summer harvests, and who wants that?!
Not sure when your last frost date is or why it matters? Find your local frost dates and more in my post on how to know when it’s safe to plant.
What You’ll Need
- Tomato seeds (duh)
- Seed starting cell trays or pots
- Drip tray
- Fine, soilless potting mix (not garden soil!)
- Grow lights (a sunny window just isn’t enough for tomatoes)
- Humidity dome (plastic wrap will do in a pinch)
- Heat mat (speeds germination but a warm spot works too)
- Plant labels and a marker
- Small fan (optional)
If you want a deeper look at setting up an indoor grow space, I walk through setting up a grow room in this post on seed starting supplies for growing indoors.
How to Plant Tomato Seeds
Fill your chosen containers with moistened potting mix. Plant seeds 1/8-1/4″ deep and tuck them in with soil. Pat down gently and water.
Cover with a humidity dome and keep the tray in a warm spot (70-75°F ideally). Seeds will germinate in 5-7 days.
Need a refresher on seed starting? I go more in depth in my Seed Starting Guide.
How many seeds should I start?
Well, how many plants do you want? Ok, I’m being facetious. But in seriousness, you’ll want to end up with at least 2 plants for every one that you want to grow. Three, if you want your backup to have a backup.
I personally go for three. You just never know when a toddler is going to sit on your seedlings.
Caring for Seedlings
Provide baby seedlings with water, light, and good airflow as they grow. Remember to keep lights close to your seedlings to prevent legginess.
If your seedlings get leggy despite your best (or worst) efforts, don’t worry. You can fix this later by burying the stem deeper. We’ll cover this part in the potting up section.
Once seedlings develop their first set of true leaves (the ones that actually look like tomato leaves), begin feeding them with a diluted liquid fertilizer.
Follow the package directions for diluting, using half-strength for seedlings. Feed seedlings once a week.
I use Espoma Organic Liquid Tomato fertilizer.
It’s higher in phosphorous (the middle NPK number) which I’ve observed tomato seedlings need at this stage. (My tomato seedlings used to all develop purple leaves until I switched to this fertilizer.)
Potting Up Seedlings
After 3-4 weeks, when seedlings have 2-3 sets of true leaves and roots start poking through drainage holes, it’s time to pot up into larger containers. (See my post on seed starting pots for ideas on recycled pots to use.)
Use 3-4 inch pots filled nearly to the top with fresh potting soil.
Carefully remove the tomato seedling from its cell and plant it with soil all the way up to the lowest set of true leaves. Remove any leaves that will be buried or touching the soil.
Tomatoes grow adventitious roots all along their buried stems, creating a stronger root system. Burying seedlings deep will also help fix legginess, but do remember to keep the lights close from now on!
Seedlings will live in these pots until transplant time in a few weeks.
Quick Tips for Growing Tomatoes from Seed
- Thin seedlings to just one per cell.
- Re-pot tomatoes to a larger pot once the roots have filled the cell.
- Bury tomato seedlings up to the lowest set of true leaves.
- Keep a fan on nearby for good air circulation and to devleop strong stems.
- Snip off any flowers that may develop indoors.
Hardening Off Your Tomato Plants
This step is crucial. Hardening off gradually acclimates your indoor-grown seedlings to outdoor conditions.
Skip this, and plants can go into shock, get sunburned, or even… die.
Start hardening off about a week before transplanting once 1) your last frost date has passed, AND 2) nighttime temperatures stay consistently above 50°F.
How to harden off plants in a week:
- Day 1: place in 1 hour of direct sunlight
- Day 2: 2 hours in direct sunlight
- Day 3: 3-4 hours of direct sunlight
- Day 4: 5-6 hours of direct sunlight
- Day 5: Full day in dappled sunlight
- Day 6: Full day in direct sun and left out overnight
- Day 7: Ready to plant
Bring plants inside if temperatures drop or a storm is in the forecast.
Transplanting Tomatoes into the Garden
Choose a weed-free spot that gets 8 hours of direct sunlight daily. Tomatoes won’t produce well in the shade.
Work 2-3 inches of rich compost into the top layer of soil.
See what tools I use for soil prep and plant care in my post on time-saving tools for gardeners.
How to Transplant Seedlings
Dig holes slightly deeper and wider than your containers. Add a handful of slow-release organic fertilizer to each hole. I use Espoma Organic Tomato-tone Fertilizer every year.
Remove the lowest set of leaves from your seedling. Pop it out of its pot and place it in the hole, burying the stem right up to the next set of leaves. This deep planting creates more roots along the buried stem and helps stabilize the plant.
Backfill with soil, pat it down, and water thoroughly.
Remove any flowers if present at planting. This will redirect a plant’s energy to focus on developing strong roots before fruiting.
Spacing
Space plants 18-24″ apart. You can place them closer if you are pruning them heavily, but wider spacing is generally best for good airflow and less competition for nutrients.
Mulching
I like to mulch my tomatoes with a light dressing of straw or shredded leaves. This retains moisture, suppresses weeds, and prevents soil from splashing onto leaves during rain or watering.
Companion Planting for Tomatoes
Certain plants grow well with tomatoes and may even improve your harvest. These include basil, marigolds, and cucumbers.
Read more about which flowers, herbs, and vegetables I companion plant with tomatoes in my garden in this post.
Ongoing Care
Keep tomatoes happy by watering deeply at the base of the plants around 3 times a week. Deep watering helps roots to grow down deeper rather than staying close to the surface.
Consistent watering also helps prevent problems like blossom end rot and split fruit. More on this below.
About halfway through the growing season, give tomato plants another handful of slow-release fertilizer scattered around the base of the plant.
Pruning Suckers
Pruning suckers (shoots growing from the point where the branch and stem make a Y) is a good way to control a tomato plant’s size, increase airflow, and to get larger, but fewer fruits. Whether or not you prune depends on how you’ll support tomatoes. (See section below.)
Supporting Your Tomatoes
All tomatoes need some kind of support to keep fruit off the ground and improve airflow.
Whichever method you choose, install supports early before plants get huge.
Method 1: Cages
For beginners, I recommend using cages and letting tomatoes bush out naturally. If you want minimal fuss, allow the plant to grow normally, removing only lower leaves or any unruly branches. Tomatoes can handle pruning, so don’t be afraid to cut off leaves or branches to keep them contained.
Do not prune if you’re growing determinate tomatoes.
Use sturdy cages to support heavy plants. Space plants further apart to allow ample room to grow (24″ minimum).
Recommended Cages:
- FlexGrow (different sizes)
- DIY wood obelisk trellis (similar to mine)
Method 2: Stakes
For adventurous beginners, you can prune plants to 1-2 stems and tie them to stakes. This is best if you have limited space or live in a very humid climate where you need to improve airflow.
You’ll remove all side shoots or suckers that grow between the main stem and branches, and also all leaves below the first set of fruit. This produces fewer, but larger fruits.
Do not prune determinate tomatoes.
Staked tomatoes can be planted closer together (18″ is ideal). Use clips or soft ties like these to attach vines to the stake.
Other Methods
There are other methods of supporting your tomatoes, such as the Florida weave and lower-and-lean techniques, but cages and stakes are a great place to start.
I’m sticking to cages this year for simplicity. You can read why and see my notes on what worked in my 2025 garden recap.
Tricks for Growing the Best-Tasting Tomatoes
Now, if you want the absolute best-tasting tomatoes of your life, there are a few tricks and tips I can share from my experience.
The Right Variety
First of all, you need to choose the right variety. I haven’t tried them all (there are literally hundreds), but the ones I’ve mentioned in this post about tomato types are my favorites.
You may need to try a few different kinds to find your favorites. Experiment with different kinds of tomatoes each year!
Strategic Stress
Second, stress your tomato plants out a little bit.
Tomatoes are fruit, and their job is to taste so amazing that animals will eat them and spread their seeds.
It’s a funny thing; just a little stress makes the tomatoes work harder to produce better tasting fruit. Too much stress, however, and you lose fruit.
Here are three ways to achieve this delicate balance:
- Reduce watering once your tomatoes begin blushing, or turning into their final ripe color. Let soil dry out more between waterings. The plants will draw the extra water out of the tomatoes to use for itself and concentrate the flavor of the fruits. Continue watering like normal after you’ve harvested the tomatoes.
- Plant tomatoes in a sunny location. The heat from the sun’s rays makes tomatoes taste sweeter and intensifies the flavor. Tomatoes grown in shade are bland and slow to ripen.
- Feed tomato plants with a higher ratio of phosphorus and potassium (the middle and last numbers on fertilizer labels) once they begin blooming. Fish emulsion like Neptune’s Harvest is stinky, but it’s worth it!
Perfect Timing
Third, you need to pick tomatoes at just the right time.
For the absolute best flavor, pick tomatoes when they are perfectly ripe on a hot, dry afternoon when it hasn’t rained in several days and you haven’t watered recently. Perfectly ripe tomatoes are slightly soft when gently squeezed and fully colored.
I always pick my tomatoes between 3 and 5pm in the summer. The heat from those extra hours in the sun really makes them taste amazing versus tomatoes that were picked in the morning when they are holding the most water.
My best-tasting tomatoes ever? Sun Gold cherry tomatoes grown in a large container on my sunniest patio, picked on a scorching July afternoon. They were like candy—sweet, complex, and bursting with flavor.
Vine-Ripening vs. Indoor Ripening
Ripening on-the-vine is supposed to produce the best flavor. The fruit continues getting nutrients from the plant and develops more complex sugars.
But indoor ripening is perfectly acceptable if you pick tomatoes once they start to show color (called “blushing”). The taste is nearly as good, and this method protects fruit from heavy rain, pests, and cracking.
Tl;dr, leave them on the vine if you can. But if rain is forecast, or if birds and squirrels are getting to them first, pick when they start to color and bring them inside.
Better to have good tomatoes than no tomatoes at all.
Troubleshooting Common Problems
Tomato Hornworms
Symptoms: Missing leaves or branches
These massive green caterpillars can strip a plant overnight. Hand-pick them off (they’re gross but harmless to us).
And here’s a fun trick: tomato hornworms glow bright green under blacklight! Go out at dusk with a UV flashlight and they’ll light up like little aliens.
Tip: Get kids involved in removing hornworms at night. They’ll have a blast and most are braver at handpicking than I am!
Birds and Squirrels
Symptoms: Bites taken out of tomatoes; half-eaten tomatoes on the ground
Birds and squirrels (and other critters) love ripe tomatoes. Protect your harvest by draping bird netting or mesh over plants or cages.
Picking tomatoes early, when they first start to blush, is also an option.
Blight
Symptoms: Brown spots on leaves that spread rapidly in warm, wet conditions
There are two types of blight (early and late), but treatment is similar: remove all affected leaves immediately and dispose of them in the trash. Do not compost.
Prevention:
- Water only at the base of plants
- Ensure good airflow with proper spacing
- Choose resistant varieties when possible (look for disease codes like “EB” or “LB” in seed catalogs)
For more on dealing with fungal diseases, see my post on powdery mildew.
Blossom End Rot
Symptoms: Dark, sunken leathery spots on the bottom of fruit.
Blossom end rot is a calcium deficiency usually caused by inconsistent watering rather than lack of calcium in soil.
Prevention:
- Water deeply and consistently (at least once weekly, more during fruiting)
- Use mulch to maintain even soil moisture
- Add calcium when planting if this is a known issue in your garden (1/4 cup gypsum per hole)
- Avoid over-fertilizing with nitrogen
Remove affected fruit. They unfortunately won’t recover. Usually only the first fruits are affected and the problem resolves with consistent watering.
Split Fruit
Too much water after a dry spell causes skins to split. Maintain consistent watering to prevent this. If heavy rain is forecast and tomatoes are nearly ripe, pick them to prevent splitting.
Harvesting Your Tomatoes (Quick Tips)
When to pick: Tomatoes are ripe when they’re fully colored for their variety and slightly soft. To check the ripeness of tomatoes (especially for green tomatoes which hardly change in appearance from immature to ripe), squeeze them gently once they have changed to their mature color.
Once the fruit feels firm yet has a bit of give, it is ripe.
Expect 60-85 days from transplant to first ripe fruit, depending on variety. Bigger tomatoes take longer to ripen.
Storage: Never refrigerate tomatoes. It kills the flavor. Store at room temperature, stem side down, and use within 3-5 days for best taste.
What to do with extras: Fresh eating is always first choice, but for preserving a large harvest, check out my post on preserving homegrown roasted cherry tomatoes. You can do this even if you don’t can. I also freeze whole tomatoes for winter soups and sauces. The skins slip right off after tomatoes are frozen.
Your Turn to Grow
Growing tomatoes from seed to harvest is one of the most rewarding experiences in the garden.
Yes, there’s a learning curve.
Yes, things might go wrong your first year.
But that first bite of a perfectly ripe, sun-warmed tomato you grew yourself? Worth it.
Start with one or two varieties this year. Pay attention to what works in your garden. Take notes and be kind to yourself.
It’s ok if it’s not perfect. You’re learning and growing.
Next year, you’ll do even better.
Happy Gardening!
Want more beginner-friendly vegetable growing guides? Check out these posts: