What to Do Before Planting Tomatoes (Growing Great Tomatoes)


When growing tomatoes, what you do before planting is just as important as what happens after planting.  This is true whether you are a first-time gardener or an experienced one trying to grow more tomatoes.

So, what should you do before planting tomatoes?  Before you plant your tomatoes in the garden, you will need to do the following to get a better harvest:

  • Find a good location
  • Choose the right varieties
  • Mark your rows
  • Ensure proper spacing
  • Install plant supports
  • Prepare your soil
  • Choose a planting or transplant date

Of course, if you are growing tomato plants from seed, you will also need to think about when to repot your plants and when to harden them off before transplant.

In this article, we’ll get into a lot more detail about what to do before planting your tomatoes and how to do it.  That way, you’ll be able to get stronger plants that will produce more fruit this growing season.

Let’s begin.

What to Do Before Planting Tomatoes

Much of the work in gardening happens before you put seeds or transplants into the soil.  There is work to be done in choosing a site, improving the soil, calculating spacing, picking the right plant varieties, and getting your timing right.

Let’s start at the beginning, with choosing a good location for your tomatoes (feel free to skip this if you already know where they are going!)

Find a Good Location

It is important to find a good location for your tomato plants.  Otherwise, giving them the best care later in the season won’t matter.

You will need to consider the following when picking a spot for your tomato plants:

  • Sunlight – tomato plants need 6 to 8 hours of sunlight per day to thrive.
  • Soil – the soil should be loose and should drain well.  Avoid heavy clay!

Sunlight

Tomato plants need 6 to 8 hours of sunlight per day to thrive.  Any less, and you may not get the harvest you are hoping for (although the vines may still grow tall and green).

daylight
Tomato plants will do best with 8 or more hours of sunlight per day. Avoid shady spots in the yard.

When choosing a spot for your tomato plants, pay attention to nearby trees.  When the leaves grow back later in the spring, they can form a canopy that will shade your entire garden.  So, choose a spot carefully and think about where the sun will be!

Soil

You should also pay attention to the type of soil in your potential garden plot.  The best soil for tomatoes is loose, drains well, and contains plenty of organic matter.

If you can, avoid heavy clay soil, since it will not drain well.  Clay soil also tends to become compacted easily when it is wet, which leaves no room for air in the soil.

clay soil
Clay soil drains poorly and becomes compacted easily, leaving less air for plant roots to breathe.

You should also avoid sandy soil, since it won’t hold water very well.  It also lacks the organic material that tomato plants love.

Sometimes, it will be a trade-off between sunlight and soil.  I would prefer a spot with enough sunlight, since you can always improve soil by adding compost (more on this later).

If the spot you choose has never been planted before, you might need to loosen up the soil.  You can do this by digging or rototilling to turn over the soil.

shovel
Digging with a shovel is slower than rototilling when breaking new ground, but you won’t need to buy or rent heavy, expensive equipment.

Digging is slower than rototilling, but digging doesn’t require you to buy or rent a big machine.  Rototillers can also be very heavy, although there are some lighter versions available.

Choose the Right Varieties

Once you have found the best spot for planting your tomatoes, it is important to choose the right varieties for your garden.  This will depend on the following factors:

  • Location (a short growing season means you want fast-maturing tomatoes)
  • Timing of harvest (determinate vs. indeterminate tomatoes)
  • Space available (some tomato plants are small enough to grow in containers or on balconies)

Location

Your location will play a large part in determining what tomato varieties you can grow.  The reason is that tomatoes are a warm-weather crop.

As such, they cannot tolerate frost.  So, for a short growing season in colder northern climates, you will need cold-tolerant and/or fast-maturing tomato varieties.

frosted leaf
Uncovered tomato plants will not tolerate frost.

For example, Fourth of July tomatoes mature in only 49 days (7 weeks).  You can learn more about Fourth of July tomatoes on the Burpee website.

Sub-Arctic Plenty tomatoes mature in 42 days (6 weeks).  You can learn more about Sub-Arctic Plenty tomatoes on the Reimer Seeds website.

Just remember that the fruit of these tomato plants tends to be smaller than other late-maturing varieties.

You can find a more extensive list of cold-tolerant and fast-maturing tomato varieties in my article here.

Timing of Harvest

You can also choose tomato varieties depending on when you want to harvest.  There are two basic types of tomato plants:

  • Determinate – these plants tend to be shorter, and they produce fruit during a limited time window of 4 to 5 weeks.
  • Indeterminate – these plants tend to be taller, and they produce fruit throughout the season, for 2 to 3 months or longer, until frost finishes them off.

You can learn more about the difference between determinate and indeterminate tomatoes in my article here.

In general, if you want to harvest all of your tomatoes in a short time frame of 4 to 5 weeks, choose determinate varieties.  They are ideal for preserving your tomatoes by canning (stewed tomatoes, pasta sauce, pizza sauce, salsa, etc.)

On the other hand, if you want to harvest fruit throughout the growing season, for 2 to 3 months or more, then choose indeterminate varieties.  They will keep growing, producing flowers, and providing fruit up until frost (and perhaps longer if you protect them from the cold – more on this later).

tomato stakes
Indeterminate tomato plants are taller than determinate ones, and so will need taller supports, such as stakes.

Online and print seed catalogs will indicate whether a tomato variety is determinate or indeterminate.  You can find a printable list of 22 indeterminate tomato varieties in my article here.

Space Available

One other thing to consider when choosing tomato varieties is the space available.  If you have a big yard and enough space for a large garden, then you can grow whatever you want.

If you are growing in containers indoors or on a balcony, then space will be a limiting factor.  Fortunately, there are lots of smaller tomato varieties that have limited growth.

clay pots
You will need dwarf or compact tomato plants to grow them in smaller containers indoors or on a balcony.

For example, Tiny Tim tomato plants only grow to about 1 foot high.  They produce mature fruit in 45 days, yielding small, red, round tomatoes that are about one-half inch in diameter.  You can learn more about Tiny Tim tomatoes on the Victory Seeds website.

The Boronia Dwarf Tomato grows a bit larger, up to 3 or 4 feet tall.  The fruit is a bit darker, similar to Black Krim tomatoes.  You can learn more about Boronia Dwarf tomatoes on the Victory Seeds website.

Mark Your Rows

Now you have chosen the right spot for your garden and the right tomato varieties.  It’s time to mark your rows so that you know where to plant.

One of the best ways to do this is to run a piece of twine along the length of the row.  First, drive a short stake into either end of the row.

Then, tie the twine to the stake at one end of the row.  Pull the string tight to the stake at the other end of the row, and tie the string to the stake.

hemp twine
Twine is great for marking rows of tomatoes, and it is also helpful for tying tomatoes to stakes as they grow taller.

The length of twine will give you a visual guide for where to put your tomato plants.  This will avoid crooked rows, and it will also be easier to space plants properly (more on this later).

If you are planning on multiple rows of tomatoes, make sure to leave enough room between rows.  The University of Illinois Extension suggests leaving 3 to 5 feet between rows of tomatoes. 

Leaving room between rows of tomatoes will give you enough space for planting, fertilizing, watering, pruning, and harvesting during the season without trampling plants in the next row. 

Ensure Proper Spacing

Within a row of tomatoes, each plant will need enough space to grow and thrive.  Without enough space, there will be problems.

For example, tomatoes spaced too close together will have to compete with each other for water and nutrients in the soil.  In addition, disease will spread more easily from plant to plant if they are too close to each other.

According to the University of New Hampshire, the ideal space between tomato plants will depend on the type of plant you are growing and the support you are using.

Tomato plants should be spaced 1 to 3 feet apart, depending on the variety and support used.

The table below gives a brief summary of the spacing you should aim for between plants in a row of tomatoes.

Type of Plant
and Support
Plant
Spacing
(inches)
stake or cage,
any type
18 to 24
no support,
determinate
12 to 24
no support,
indeterminate
24 to 36
A summary of the spacing between tomato plants, depending on type of plant and support.

You can mark the spacing with plant markers if you wish.  However, since you will probably want support for your tomato plants, you can simply use the cages or stakes themselves to mark the spacing.

Install Plant Supports

Installing support for your tomato plants will make them easier to manage and grow.  They will take up less space in the garden, be less prone to disease, and it will be easier to harvest when fruit ripens.

You can learn more about why tomato plants need support in my article here.

You can use cages, stakes, or a trellis to support tomato plants.  In general, you would use tall stakes for indeterminate tomato plants, short stakes or cages for determinate tomato plants, and a trellis for either type (you need a taller trellis for taller plants, such as indeterminate varieties).

Type of
Plant
Type of
Support
Determinatecage, short stake,
or short trellis
Indeterminatetall stake or
tall trellis
Support for determinate and indeterminate tomato plants.

The size of the stake will depend on the height of the plant, so check the seed catalog.

For example, if the plant reaches a maximum height of 5 feet, then you might want a stake that is 6 feet tall: 1 foot underground after you drive the stake into the ground, and 5 feet above ground for the plant to climb.

wood trellis
A trellis is another option for supporting tomato plants as they climb.

Any of the supports mentioned above would work if you are planting tomatoes in a raised bed.  For container planting, a short cage would probably work best, although a small might stake would work.

Just be sure there is enough weight in the bottom of the pot to prevent it from tipping over.  A few heavy rocks in the bottom of the container (below the soil) should help with balance.

Also, remember to install supports before you transplant tomatoes into the garden.  Otherwise, you could hurt the root system of an established plant.

Prepare Your Soil

Now it’s time to prepare the soil around the spot where each tomato plant will go.  That means ensuring the proper pH and nutrients in the soil and adding organic material as needed.

Soil Consistency and Organic Matter

Ideally, you chose a spot where the soil has a good consistency.  However, it doesn’t always work out that way.

Whether your soil is clay or sand, you can improve its consistency by adding organic material.  Having the right balance of organic material will keep soil moist, but not too wet (clay drains poorly, while sand does not retain water long enough).

Normally, organic material comes in the form of compost or aged manure.  In addition to improving the soil consistency, compost also adds nutrients to the soil.

compost bin
Compost is a great way to add nutrients and organic material to your soil.

You can buy compost from a garden center, or you can make your own.  You can make compost with common yard and kitchen scraps such as grass clippings, fallen leaves, and vegetable leftovers.

You can learn more about how to make your own compost in my article here.

When you have your compost and it is aged and decomposed, dig a hole in the garden where you want to add the compost.  Put the compost in the hole, and replace the soil you removed, mixing them together until they are blended.

Soil pH and Nutrition

The pH and nutrient levels in your soil are important for healthy plant growth.  The soil might be ok as it is, but it is a good idea to check.

A do-it-yourself soil test will tell you the pH and nutrient levels in your soil (at least for the “big three” nutrients: NPK, or nitrogen, phosphorus, and potassium).

A soil test from a lab at an agricultural extension office will give you more detailed information, along with recommendations if you tell them what you are growing.

You can learn more about how to do a soil test in my article here.

The University of Georgia Extension suggests that a pH of 6.2 to 6.8 is ideal range for tomato plants.  Don’t fret if yours is a little outside this range.

However, if the soil is too acidic or too basic (alkaline), the plant could have trouble absorbing nutrients from the soil.  You can raise the pH of acidic soil by adding lime (calcium carbonate), and you can lower the pH of basic soil by adding elemental sulfur.

If the soil test shows a lack of any nutrients, then it might be necessary to use some fertilizer.  You can find fertilizers with different amounts of nutrients, such as 10-10-10 (10% nitrogen, 10% phosphorus, and 10% potassium).

You can learn about what the numbers on a fertilizer package mean in my article here.

When adding fertilizer, always follow the directions on the package.  Adding too much fertilizer at once can hurt your plants by burning their roots.

Now your soil is ready for planting tomatoes – all you need to do is to figure out when to plant or transplant.

Choose a Planting or Transplant Date

The date that you plant your tomatoes will depend on whether you are direct sowing or transplanting.

Direct Sowing

Direct sowing means planting seeds directly in the garden.  This is not recommended for colder climates with a short growing season, since tomato plants cannot tolerate frost.

Direct sowing tomato seeds into your garden is not ideal in cold regions with a short growing season, since tomatoes cannot tolerate frost without cold protection.

Transplanting means starting seeds indoors (or buying established plants) and putting them out in the garden later in the season.  For most gardeners, this will be the preferred method of planting.

Transplanting

When transplanting into the garden, you will need to either buy established tomato plants or grow your own from seed.

Buying Transplants

You can buy established tomato plants from a garden center or online.  The University of Maryland Extension suggests choosing plants that are 6 to 10 inches tall.

Some gardeners do not like to buy transplants that are already flowering.  Either way, the plants you choose should always be strong, not thin or spindly.

tomato seedling
Tomato plants should be 6 inches or taller before you transplant them outside – this one is still too small!

A thin “stretched out” or “leggy” appearance indicates a lack of light during the tomato plant’s early development.   This will probably result in less than optimal results later in the season.

Starting Tomato Plants from Seed

The Old Farmer’s Almanac suggests starting tomato plants from seed indoors 6 to 8 weeks before the last spring frost date in your area.

You can find the last spring frost date in your area with this calculator from the Old Farmer’s Almanac.

For example, let’s say the last spring frost date in your area is May 15, and you want to start seeds indoors 7 weeks (49 days) before that date.

Then you would want to work backwards 7 weeks (49 days) from May 15.  That means 15 days in May, 30 days in April, and 4 days at the end of March.  So, you would start your tomato seeds indoors around March 27.

tomato seedling
You can start tomato seeds in a tray indoors, 6 to 8 weeks before the last frost date in your area.

You may need to repot your tomato plants before transplanting outside.  You can learn more about repotting and transplanting tomato plants in my article here.

In general, you should wait until after the last spring frost date in your area to move tomato plants outside.  Before transplanting, check the weather forecast for any late spring frost.

You may want to delay transplant if the weather calls for unseasonable cold.  Prolonged exposure to temperatures in the 40’s or 50’s Fahrenheit can damage tomato plants and stunt their growth.

In an area with a short growing season, there might not be much time to delay transplant.  Or, perhaps cold weather is threatening after you have already transplanted.

In that case, you can use cloches and row covers to keep your tomato plants a little warmer.  Taking these measures could mean the difference for their survival on cold nights!

A cloche is a plastic or glass cover that goes over a young plant to protect it from cold, wind, and insects.  By acting as a mini greenhouse, a cloche will keep plants a little warmer by trapping heat from the sun “under the dome”.

You can make a cloche out of a clear, empty plastic bottle by cutting out the bottom and using the cap as a vent.  You can learn more about cloches in my article here.

water bottles
You can make a cloche out of a clear plastic bottle to protect young tomato plants from cold.

If you want to increase your tomato plant’s chances of survival, it is a good idea to “harden off” the plant before putting it in its permanent location in the garden.

To harden off a tomato plant means to gradually expose it to more of the outdoors: that means the elements such as cold, wind, and sunlight.

Once your seedlings are hardened off and transplanted into the garden, they will be well on their way to providing you with plenty of tomatoes.

Conclusion

Now you know where to start with planting tomatoes – before you even sow a single seed.  You will be on your way to a better harvest in no time!

I hope you found this article helpful.  If so, please share it with someone who can use the information.

If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here.  Enjoy!

~Jonathon

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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