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How to start seeds in milk jug greenhouses

on September 19, 2023

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Starting seeds in milk jug greenhouses is a cost-effective and environmentally friendly way to kickstart your gardening season. It allows you to nurture young plants and extend your growing season before transplanting them into your garden. In this comprehensive guide, we'll take you through the entire process, from gathering materials to transplanting your seedlings into your garden. 

What You'll Need for Your Milk Jug Greenhouses

Before you start, it's crucial to gather all the necessary materials. Here's what you'll need to create and maintain your milk jug greenhouses:


  1. 1. Milk Jugs: Collect clean, empty milk jugs with lids. Ensure they are washed and sanitized to prevent mold and disease.
  2. 2. Potting Soil: Use high-quality potting soil or seed-starting mix. It should be sterile to avoid introducing harmful pathogens.
  3. 3. Seeds: Choose seeds based on your gardening goals, considering factors like your planting season, climate, and available space.
  4. 4. Labels: Durable labels are essential for identifying your seeds and noting the planting date.
  5. 5. Cutting Tool: You'll need a sharp utility knife or scissors for cutting the milk jugs.

Preparing Milk Jug Greenhouses

Cleaning and Cutting

Start by cleaning the milk jugs thoroughly with warm, soapy water. Rinse them well and sanitize them by soaking them in a mild bleach solution for a few minutes. Next, carefully cut the milk jugs, typically around two-thirds of the way up, leaving the top as a mini greenhouse.

Drainage Holes

Proper drainage is essential for the health of your seedlings. Make drainage holes in the bottom of each milk jug to ensure excess water can escape. This prevents waterlogging, which can be detrimental to young plants.

How to Start Seeds in Milk Jug Greenhouses

Now that you've gathered your materials and prepared your milk jug greenhouses let's dive into the process of starting seeds:

Selecting Seeds

Choose seeds that align with your garden's needs and your location. Consider factors such as your hardiness zone, planting season, and whether you want to grow flowers, vegetables, or herbs. Different plants have various requirements, so ensure you select seeds that suit your gardening goals.

Planting Seeds

  • Fill the Milk Jugs: Begin by filling the lower section of the milk jug with potting soil or seed-starting mix. It's crucial to use high-quality, sterile soil to prevent introducing harmful pathogens to your seedlings.
  • Planting Depth: Plant the seeds according to the package instructions, ensuring you follow the recommended planting depth and spacing. Different seeds require different planting depths, so be sure to read the guidelines provided.
  • Watering: After planting the seeds, water the soil thoroughly. This helps to settle the soil and ensures that it makes good contact with the seeds.


Label each milk jug with the seed type and planting date. This step is essential for tracking growth and identifying your seedlings later. It's easy to forget what you've planted, especially if you're starting multiple types of seeds.


Regular and appropriate watering is essential for successful seed germination. Maintain soil moisture consistently without excessive wetness. A spray bottle or delicate watering can aid in achieving uniform moisture distribution. Prevent both complete soil drying and waterlogging.

Caring for Your Seedlings

As your seedlings grow, they require specific care to thrive in their mini greenhouse environment:

Placement and Sunlight

Position the milk jug greenhouses in a sunny location, ideally receiving at least 6-8 hours of direct sunlight daily. Be mindful of temperature fluctuations to prevent exposing your seedlings to extreme heat or cold.


Proper ventilation is crucial for your seedlings' health. Open the milk jug lids during the day to prevent overheating inside the mini greenhouses. Closing them at night helps to trap some warmth and protect against cooler temperatures.

Watering and Maintenance

Continue to water your seedlings as they grow, maintaining even moisture to prevent them from drying out or becoming waterlogged. It's also essential to check your seedlings for any signs of pests or diseases regularly. 

Transplanting Seedlings

When your seedlings have grown sufficiently and outdoor conditions are favorable, it's time to transplant them into your garden or larger pots. However, this process requires some care and attention to ensure the successful transition of your young plants:

  1. Acclimation: Gradually acclimate your seedlings to outdoor conditions. This process, known as hardening off, involves exposing your seedlings to outdoor elements like sunlight, wind, and lower temperatures. Start by placing them outdoors for short periods and gradually increase the exposure.
  2. Timing: Choose an appropriate time for transplanting based on your region's last expected frost date and the specific requirements of your plants. Transplanting too early can expose your seedlings to frost while transplanting too late can hinder their growth.
  3. Soil Preparation: Prepare the planting area by amending the soil with compost or organic matter if necessary. Ensure the soil is well-draining and suitable for the type of plants you're transplanting.
  4. Planting Depth: Transplant your seedlings at the same depth they were growing in their milk jug greenhouses. Firmly pat the


1. Why should I start seeds in milk jug greenhouses?

Starting seeds in milk jug greenhouses offers several advantages. It provides a controlled environment for germination, protects seedlings from adverse weather, and allows for an early start to the growing season. Additionally, it's a sustainable and cost-effective method.

2. What seeds can I start in milk jug greenhouses?

You can start a wide variety of seeds in milk jug greenhouses, including vegetables, herbs, flowers, and even some small shrubs. Choose seeds that match your climate and planting season.

3. What's the best location for my milk jug greenhouses?

Choose a sunny location with at least 6-8 hours of direct sunlight per day. Be mindful of temperature fluctuations to avoid exposing your seedlings to extreme heat or cold.

4. How often should I water the seedlings?

Water your seedlings consistently to keep the soil moist but not waterlogged. Use a spray bottle or gentle watering can to maintain even moisture distribution. Avoid letting the soil dry out completely.

5. Can I reuse milk jug greenhouses for future seedlings?

Yes, you can reuse milk jug greenhouses for multiple growing seasons. Ensure that you clean and sanitize them between uses to prevent the buildup of pathogens.

6. Are milk jug greenhouses suitable for beginners?

Yes, starting seeds in milk jug greenhouses is an excellent option for beginners. It's a straightforward and budget-friendly method that allows you to learn about seed germination and care before transplanting seedlings into your garden.