Seed Starting in Milk Jugs | Easy (and actually works)! (2024)

Instead of using forking out money for even a moderately priced grow light, you can start your spring and summer garden for pennies by winter sowing in milk jugs. It’s cheap, it’s simple, there’s virtually no maintenance. Better yet- it actually works.

What is winter sowing?

Winter sowing is the process of placing seeds in closed containers to create a mini greenhouse that is kept outdoors. It is an especially enticing method for those of us that don’t have room for sowing indoors (ya’ know, because you need tables or tiered shelving racks, drip trays, growing flats, etc.) or prefer to avoid expensive grow light purchases but still want to grow from seed. Winter sowing allows seeds to get better germination rates, is excellent for cool season herbs and vegetables, and is inexpensive.

Wait, you’re telling me milk jugs grow plants?

Well, kinda. A milk jug provides plants with their own individual greenhouse that creates and maintains the ideal microclimate a seed needs to germinate. Cool season crops require a process of ‘hardening off’ which automatically happens when jugs are kept outside through the winter, naturally experiencing cold weather conditions. This exposure stops seed dormancy and triggers germination more successfully than seeds grown indoors.

So, what are the benefits of sowing in milk jugs?

There are many benefits to sowing in milk jugs. Here are a few:

• Space Saving. There’s no need to find “extra” space in your house to store seedling trays or racks. That’s because your milk jugs will be kept outdoors on a deck, porch, steps, or directly on your lawn!
• No Grow Lights Required. You don’t need to grow lights (which you can easily spend a small fortune on), have to hassle with timers, UV light combinations, or deal with leggy starts that end up getting too much (or not enough) exposure.
• Eliminates dampening off risk. This is a common fungal problem for cool-season crops started indoors, but rarely happens with winter sowing! This is because environmental conditions are optimal outdoors and difficult to replicate (and easy to mess up) indoors.
• End the hardening off hassle. Hardening plants off is essential. But I hate doing it. Like, really, really hate it. Who has time for all the back and forth? Not me, not you. Starting seeds in milk jugs starts and keep your plants outdoors, checking this chore off your list.
• Stronger plants. Seeds grown in greenhouses are always stronger than their indoor peers. Why? Because they have a home-court advantage. Milk jug plants have had exposure to the native environment they’ll spend their entire life growing, thriving, and surviving in. They’re tough.

How do you plant seeds in milk jugs? Here’s the process in 10 easy steps.

1. Select your containers. You can almost select anything to grow in as long as it’s opaque (so the sun can get through). Plastic milk jugs are a popular choice because they provide a dome shape that lets in plenty of light, traps heat and moisture, and are easy enough to get your hands on. Some other examples include take-out containers, water jugs, 2-liter soda bottles, rotisserie chicken containers.
2. Prepare your containers. Wash, rinse, and clean your containers with mild dish soap to remove any residue. Then, puncture the center of the container (or around 5-6 inches from the bottom) and cut around the middle leaving about a half-inch to act as a hinge. Next, create a pattern of drainage holes on the base of the container using a drill or paring knife. Recycle the caps, you don’t need them.
3. Next, you’ll need soil. Potting soil that is. Believe me, this is not something you want to substitute. These seeds will be sitting outside so an indoor seed starting mix will be too light and regular garden soil will be too heavy. Potting soil is your Goldilock fit! Add a minimum of 4 inches of damp soil to each container. Planting needs to be done is soil that is neither dry nor soggy. Using damp soil will ensure your plants won’t dry out or die and provide sufficient root growing space.
4. Sprinkle your seeds. Sprinkle your seeds on the surface of the soil. You want to add enough seeds to ensure you have successful germinations, but not so many that you crowd things out and end up with a mess to untangle. Check the seed packet to see how deep to plant. Gently pat the seeds to press into the surface of the soil and sprinkle a very thin layer of damp potting mix on top.
5. Lock and Label. Use 2-3 wraps of duct tape to seal the container. Use a permanent marker to label your container. I recommend labeling your container in two places (top and bottom of your container) because even “permanent” markers fade over time, especially when exposed to light. Alternatively, you can use a paint pen, which is least likely to fade in UV light and cold, wet conditions.
6. Soak up the sun. Place your containers in an area where they’ll get the most amount of sun if you live in moderately cold conditions or partial sun if you live in a milder climate. Once your seedlings germinate, this location will give them the right amount of sun exposure. Pro tip: I strongly recommend storing them in a milk crate or shallow container to prevent strong winds from blowing your milk jugs over (which would just be a tragedy of unbearable measure)!
7. Hurry up and… wait. Yup, this is exactly what you’ll do. Be sure to check on your plants at least weekly, but you’ll observe absolutely nothing for the next few weeks or months. And that’s to be expected. No news is good news.
8. Behold, you’ll (eventually) see “green”. Yes, one glorious day, you WILL see something sprout! And that’s when you’ll have to shift from passive to active mode. As your seedlings grow, they’ll need more air circulation, so you’ll need to puncture the top of your containers with extra draining holes and/or cut out a window vent. You’ll also need to start watering your seedlings to keep the soil moist.
9. Keep blankets close. Sometimes the weather is sporadic. Scratch that, weather IS sporadic. Once you have seedlings an unexpected cold spell can knock out all your work. That’s why I recommend keeping some type of covering (old blankets, towels, burlap, etc) to cover your containers any time the temperature will dip below 40 degrees.
10. Transplant to your garden (or larger container). Once your seedlings start to touch the top of your container and the roots are 1-2 inches long and hold together, congratulations, they’re ready for the garden. See how easy that was?

Have you tried winter sowing in milk jugs? Are you strongly considering this method because you’re looking to avoid the hassle of grow lights or are short on space?If you’re craving more small space gardening hacks, you’ll want to check out how to create your own tote bin worm farm so that you can have access to THE BEST garden fertilizer (worm castings) on demand.