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Growing Tomatoes In A Planter Box (The Complete Step-by-step Guide)


Tomatoes are not reserved for the kitchen garden and the open ground. They grow very well in pots or planter boxes, on a balcony or terrace well exposed to the Midi or afternoon sun.


The harvest is sometimes very abundant, especially with small fruit varieties. Here are all the advices to successfully grow your tomato plants in a planter box.


When to plant your tomatoes in a planter box?

Plant the seedlings between the beginning of May and mid-June. Earlier, cooler nights may make your tomatoes want to show the tip of their nose.


Sowing seeds or buying tomato plants?

The lucky ones with a heated greenhouse know that they can start sowing tomatoes as early as January, transplant at the end of February and harvest… as summer approaches.


In an unheated greenhouse, the seeds will be sown in March, for a harvest from July to October.


If you buy your tomatoes in garden centers or at plant festivals, choose plants in cups about 15 centimeters high, with stems the diameter of a pencil. Taller, skinny or even flowering plants do not have a better chance of recovery.


How to plant your tomato plants in a planter box?

  1. Take a planter box
  2. Fill the planter box with clay balls from ¼.
  3. Fill the planter box with potting soil.
  4. Dig a hole in the soil with the transplanter to insert the plants.
  5. Soak the plant in water for 5 minutes.
  6. Gently loosen the roots so that the plant will take better in the soil.
  7. Insert the plant in the soil and pack the soil.
  8. Place a stake, well inserted in the pot, and come to fix the plant.
  9. Mulch the surface of the pot to avoid water evaporation.


Choosing the right substrate

To grow tomatoes in a planter box, you must provide them with a rich and fertile substrate. To do this, follow these 3 steps:

  • Place a drainage layer at the bottom of the pot (5 cm).
  • If you have garden soil, mix it with potting soil and fill 2/3 of the pot. Otherwise, use only potting soil.
  • Top up with well decomposed manure or compost.


To improve drainage, incorporate vermiculite (commercially known as perlite) or pozzolana into the substrate. The latter will keep moisture in the soil while allowing good water circulation.


Bring fertilizer

The tomato is a greedy plant and, despite your efforts to create the best possible substrate, it will need a helping hand. Also, when watering, don’t hesitate to add a little fertilizer to your tomatoes.

The important thing is not the quantity, but the frequency (every 15 days for example). Give the plant time to absorb what you give it.


What fertilizer should be used to stimulate the growth of tomatoes in the planter box?

Before putting your tomato plants in pots, prepare the soil. Mix a handful of dehydrated cow dung and/or some ripe compost into the potting soil and then plant the tomatoes.

You can also put crushed eggshells at the bottom of the hole.


All these inputs allow the tomato plants to draw on this reserve of nutrients to grow better. Vegetable fruits are very greedy plants and need a well enriched soil to give you good harvests and to strengthen themselves.


When to water tomato plants in a planter box?

Tomato plants grown in a planter box need moist soil, so water them regularly. You need to keep the soil cool and moist to the touch. It should not be drowned!


Cut off excess leaves

Plants lose water through the stomata of their leaves. This phenomenon is called evapotranspiration.


To successfully grow tomatoes in a planter box, your role will be to find the subtle balance between leaving enough leaves for a healthy plant and eliminating others that cause the plant to lose precious liquid resources (often called “greedy”).


Tomato harvest

Early May plants will give their first fruits in mid-July. For plants with larger fruits, the first harvest will be in August and September. If the late season is warm, harvesting can be extended into the fall.


How to store tomatoes

The tomato season lasts only a short time despite the fact that tomatoes are found almost all year round in supermarkets. So to have the luxury of eating tasty tomatoes throughout the seasons, here are some small conservation recipes to make:

  • tomato jam
  • green tomato chutney
  • in tomato sauce
    • to be put in a sterilized jar
    • to be frozen in ice cube trays
  • tomato coulis
  • homemade ketchup sauce
  • chili sauce with chili peppers grown on the balcony
  • candied whole
  • on a pie, in a savoury cake or on a pizza (which you will freeze to enjoy at a family meal).



You can consider growing tomatoes in a planter box on the formal condition that you can place your pot(s) in a very sunny place (terrace, balcony, courtyard). Tomatoes are one of the vegetables that require the most sunlight and inadequate exposure would only lead to disappointment.


To have good harvests, the first and most important thing is to fill the jar with a rich mixture because tomatoes are a greedy plant, and the second thing is to never let the jars run out of water.

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