How to Grow Tomatoes in Styrofoam Cups Indoors in Winter


Nothing is as delicious to a tomato lover as a bowl of sun-ripened, home-grown, ruby-red succulence. Tomatoes in the winter just don't have the color, flavor and scent of the local, in-season ones. Grow your own winter tomatoes indoors and say goodbye to bland, colorless salads, salsas and sauces.

Step 1

Poke a 1/4-inch-diameter drain hole in the bottom of each 32-oz. Styrofoam cup. You will need one cup for every three tomato plants you wish to grow.

Step 2

Pour round river gravel 1-inch deep in the bottom of each cup. The river gravel will prevent soil compaction.

Step 3

Crush 1/4-cup eggshell into each cup. Eggshells do not increase calcium absorption by the tomato plant. Only adequate watering will do that, according to Steve Reiners, Associate Professor of Horticultural Sciences, Cornell University. The eggshells prevent soil compaction and serve as mulch, keeping moisture in the soil longer.

Step 4

Add 1 tsp. sugar to each cup.

Step 5

Fill each cup with 2 inches of shredded paper to reduce the amount of soil you will need.

Step 6

Fill the remainder of the cup with composted soil or worm castings to within 1 inch of the top edge.

Step 7

Place 3 to 4 seeds in each cup, evenly spaced on the surface of the soil. Use your fingertip to push each seed under the soil to your first finger joint. Cover each seed with loose soil.

Step 8

Pour 1 cup of water into each cup, taking care not to wash the seeds out of position.

Step 9

Place the cups in a window with a southern exposure or in front of a set of patio doors in full sun. Water only when the soil does not feel damp to the touch, 1/2 cup each time. If available, use compost tea instead of tap water, to avoid mineral buildup in your soil.

Step 10

Hand-pollinate your tomatoes by shaking the flowers onto one another or by vibrating the flowers with an electric trimmer with its blade removed.

Step 11

Transplant to 15- to 24-inch pots when plants exceed 12 inches in height. To reduce potential transplant shock, prepare the pots as in steps 1 through 6. Dig a hole in the soil in each container the same diameter and depth as the dimensions of the Styrofoam cups. Break the cup along each side in three or four places.

Step 12

Place the broken cup in the hole and pull soil around it. Water the pot until the soil sticks to your hand when you lay your hand on the soil surface. Use only 1/2 cup of water in the original cup. Eventually, your tomato plant's roots will reach toward the outer pot as they seek water.

Tips and Warnings

  • Growing tomatoes indoors in winter is a challenge. Tomatoes will outgrow most starter pots long before they are ready to flower. Lack of pollinators may keep your plants from setting fruit, or transplant shock might cause established plants to lose both flowers and fruit, making them worthless.

Things You'll Need

  • 32-oz. Styrofoam cups
  • Round river gravel
  • Eggshells
  • Sugar
  • Shredded paper
  • Composted soil or worm castings
  • Tomato seeds
  • Water
  • Compost tea
  • 15- to 24-inch diameter, 15- to 24-inch-tall plant pots


  • New York State Agricultural Experiment Station: Ten Mistakes to Avoid When Growing Tomatoes
  • Charles Sturt University Woodland Web: Add Sugar and Kangaroo Grass and Burn in Spring

Who Can Help

  • Green Culture Singapore: Hand Pollination Guide for Tomatoes
  • Pollinator: Tomato Pollination Graphics
  • USDA Ag Research Service Carl Hayden Bee Research Center: Why Is That Bee Giving Me a Raspberry?
Keywords: indoor tomato gardening, styrofoam tomato containers, organic indoor tomatoes

About this Author

Jane Smith received her Bachelor of Science in education from Kent State University in 1995. She provided educational supports for 11 years, served people with multiple challenges for 26 years, rescued animals for five years, designed and repaired household items for 31 years and is currently an apprentice metalworker. Her e-book, "Giving Him the Blues," was published in March 2008.