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Organic Gardening Tips for Milk Carton Seed Starts

Susan Patterson
Milk Carton

A few creative organic gardening tips for starting seeds in milk cartons will help you get a jump on the growing season in your garden this year. Starting seeds early for planting out in spring is a fun and rewarding way to begin an herb, vegetable or flower garden inexpensively and can also help teach children about the natural world of plants.

Milk Carton Advantages

There are definite advantages to using milk cartons for seed starting.

  • Eco friendly, and easily available at zero cost
  • Right size to accommodate 2-3 months of plant growth
  • Sturdy, and easy to transport outside later
  • Less prone to decay and damage by molds, unlike paper tubes
  • The thick walls will keep the root zone warmer during the cold season and promote plant growth
  • Milk cartons will break down naturally, and become part of the soil once they're planted in the landscape. This means less transplanting work for you and little or no risk to the root systems of your delicate seedlings.

When recycling milk cartons, either cut them into two, to form 2 square containers for individual planting, or cut off one long side to form a rectangular one that can contain multiple plants. Just make sure that they are about four inches high and very clean. Don't forget to add about five holes at the bottom, about the diameter of a pencil, for good drainage.

Getting Started

Choosing Seeds

Choose seeds that will benefit from an early start. Some plants require an earlier start than others. Taking into account their individual needs, seeds can be planted in succession.

For example, onions and leeks can be started more than 3 months in advance. While vegetables from the cabbage family require a head start of 21/2 months, eggplants and tomatoes need about 6-8 weeks only.


Clean the cartons and line the bottom with a layer of kitchen paper to prevent soil run-off. Fill it up with the starter medium. Add water and check drainage. You may see some settling down of the soil. Add more soil to make up.


Read seed packets carefully to learn the best growing medium and planting depth for the varieties you've selected. While some seeds can remain very close to the surface of the soil, others should be covered with growing medium to a specific depth, like 1/4 to 1/2 of an inch.

The rule of thumb is the bigger the seed, the deeper it must be planted. Mix tiny seeds with fine sand and sprinkle on top of the wet soil.


Make sure you choose an indoor location for your seed pots that gets six to eight hours of light a day and isn't close to heating vents or exterior doors. Your young plants will also fare best if you can maintain an indoor temperature between 65 to 75 degrees F.

Turn plants regularly so that they will develop evenly on all sides.


Remember to water regularly. Be prepared to water your seedlings often, but only when the soil is dry to the touch.

Keep a pump spray bottle nearby to help increase the humidity around the seeds and plants.

Bottom watering may be ideal for delicate seedlings. Stand the container in a tray with two inches of lukewarm water for 5 minutes.

Keep track of your planting

Label each pot with the plant name and the planting date for easy identification.

For vegetables that can be harvested quickly, like lettuce, you may want to start successive seed plantings every few weeks to keep a constant supply throughout spring and summer.

Using Organic Seeds and Soil

  • When choosing organic seeds, always check the sell-by date to get the current season's batch. Look for the "Certified Organic" insignia on seed packaging.
  • Seeds that have organic certification have been grown and harvested in accordance with strict USDA guidelines.
  • Organic produce begins with these wholesome seeds, which are typically grown in small batches without chemical fertilizers or insecticides. Organic seeds are selected from hardy genetic stock with natural resistance to insects and disease.
  • Choose a quality organic soil or a soil-less medium to start your seeds. A mixture containing equal parts of peat and sand is ideal for seed starting.
  • Look for organic fertilizers, like Terra Cycle or Humic Plus from Echo Chem, that do not contain harmful chemicals.

Transferring Seed Starts to Your Garden

  • Accustom seedlings to the outdoors by moving them gradually over the course of a week or more. Try leaving them out a little longer each time, and watch that they aren't getting too much sun. This is called hardening.
  • If each milk carton container has only one seedling, you can bury it directly in your prepared bed until the base of the plant is level with the top of the soil. The carton will deteriorate over time. Making a few slits on the sidewalls is helpful.
  • Pay careful attention to the distance recommendations that came with your seeds. If multiple seedlings are growing in one container, gently remove them from the container and separate the seedlings. Providing enough room for plants to grow helps protect them from stress and maintains good air flow that discourages fungal and bacterial growth.
  • Keep an eye out for insects. Some insects, like Japanese beetles, can be removed by hand, eliminating the need for insecticides. If you do need to employ a bug spray, look for organic products using natural ingredients, or consider making your own from plant parts, dish soap, and water, or using other homemade recipes.
  • Try companion plantings to keep pests away too. Strongly scented plants, like garlic and sage, are naturally bug repellent and discourage insects and even rodents and deer from eating your plants.
  • Remove any dead or dying plants immediately. Decaying vegetable matter, even lawn clippings and tree leaves, can attract insects that will stay around to feast on your plants.

Have Fun

Growing plants organically is a rewarding and pleasurable experience that can be fun for the whole family. Starting seeds in milk cartons is a great recycling project that not only teaches the value of environmental consciousness but also sustainability.

Organic Gardening Tips for Milk Carton Seed Starts