This Free Mini Greenhouse Is Easy to Make with an Egg Carton and a Bread Bag – and It’s Perfect for Starting Seeds at Home

If you’ve been wanting to start a garden from seeds, but it’s too cold out, and you can’t afford a fancy shmancy greenhouse, this hack is for you.

All you need is a cardboard egg carton to use as your seedling tray, then, to make it into a mini DIY greenhouse, simply slip it inside a clear bread bag, similar to this video below by @itsplantsyall on TikTok. No major equipment or big investment; just two things you probably already have in your kitchen.

The actual setup costs next to nothing, takes about five minutes, and is a great hack for starting seeds indoors before the growing season begins. This will have you wondering why you’ve been wasting money on plastic seed trays and humidity domes all these years.

What You'll Need

Before you get started, make sure you have these materials on hand:

• 1 cardboard egg carton (it should be paper/cardboard only, not styrofoam)
• 1 clear plastic bread bag (or any clear plastic bag large enough to fit the carton)
• Seed starting mix (if you don’t have seed starting mix, regular potting soil works fine)
• Your chosen seeds
• Water

Optional but helpful:

• A spray bottle for light watering
• Something pointy for poking drainage holes (like a pencil)
• A marker for labeling seeds
• If you prefer real labels, these ones from Kinglake on Amazon are a great size and even come with a marker.
• Something to put underneath to catch water drainage

Step-by-Step Instructions

Step 1: Prepare your egg carton

Open your egg carton and use a pencil (or another pointy tool) to poke a small drainage hole in the bottom of each cup. One small hole per cup is enough, as this is done to keep water from pooling in the bottom and causing seed rot.

Step 2: Fill with soil

Fill each egg cup about ¾ full with your seed starting mix or potting soil. You’ll want to have some space at the top to keep soil from going over the edges when you add water, and it gives seeds room to settle.

Don’t pack it too firmly, otherwise your roots can’t penetrate easily, and water won’t drain through.

Step 3: Plant your seeds

You should always follow the instructions on your seed packet for how deep to plant seeds. But, as a general rule:

• Super small seeds (like lettuce or herbs) should sit gently on the surface and be barely covered.
• Medium seeds (like tomatoes or peppers) go about ¼ inch deep
• Larger seeds (like beans or peas) go about ½ inch deep

Plant 1-2 seeds per egg cup. If they both germinate, you can thin seedlings or separate them when transplanting.

Step 4: Water gently

Don’t go all crazy when watering seedlings, as you will end up oversaturating them. Use a spray bottle to mist the soil so it becomes moist but not clogged with water. This approach will prevent the seeds from moving around or getting buried too deeply.

You can also water from the bottom by placing your egg carton in a shallow tray of water; this works great for tiny seeds.

Step 5: Label everything

Don’t skip this step because, as much as you think your memory is super good, it’s probably not. Use a marker to label each cup; future you will be thanking current you.

Step 6: Create the greenhouse

Slide the entire egg carton into your plastic bag. The bag doesn’t need to be sealed completely, and sometimes it’s even better to leave it slightly open for some air circulation, which prevents mold. You want humidity, not a completely airtight environment.

Step 7: Find the right spot

Okay, you’ve made your mini greenhouse, but where to place it? You need a warm location with indirect light. Some options could be:

• On top of the refrigerator (the warmth from the motor helps)
• Near (but not directly on) a heat source like a radiator, or use a heat mat – like this BN-LINK Seedling Heat Mat with Thermostat Controller Combo Set from Amazon.
• On a sunny windowsill (though be careful it doesn’t overheat)
• Under a grow light, if you have one – this GooingTop LED Grow Light is ideal.

Most seeds need a temperature of about 65-75°F (18–24°C). The plastic bag will trap some heat, so you don’t need extreme warmth, just a spot that is consistently warm.

Caring for Your Seedlings

Once you’ve got your mini greenhouse, it doesn’t need a lot of maintenance, but still, a bit is required.

Monitor moisture: Do a daily check by looking at the soil through the plastic, and making sure it’s moist but not soggy. Condensation on the inside of the bag is totally normal; this is the greenhouse effect in action.

Watch for germination: Most of the seeds will begin sprouting in 1-2 weeks, depending on what type they are and the conditions of your mini greenhouse. Monitor them, and once you see the green shoots emerging, they need light immediately to prevent getting leggy (this is plant speak for too much stem space between leaves that can cause it to get weak).

Ventilate once sprouted: Once your seedlings have sprouted, open the bag more or entirely remove it for part of the day to increase air circulation. This is when you’re transitioning from a high-humidity germination phase to a growth phase that requires more air movement.

Thin if needed: If both of your seeds have sprouted, you’ll need to snip the weaker one to soil level with scissors. Don’t pull it out, or you will disturb the roots of the one you want to keep.

These Fiskars Shaper Plant Shears from Amazon are super sharp and perfect for small snips.

What Seeds Work Best?

Not all seeds will work for starting in an egg carton, mostly due to size constraints.

Great choices for egg carton greenhouses:

• Herbs (basil, cilantro, parsley, dill)
• Lettuce and salad greens
• Tomatoes (transplant relatively early)
• Peppers
• Flowers (marigolds, zinnias, cosmos)
• Broccoli
• Spinach

A Hack Accessible to Everyone

In a world where gardening seems inaccessible unless you have a ton of specialized equipment, an egg carton greenhouse is a great reminder that you can start from almost nothing. This is a great hack for beginners, kids, people on tight budgets, or those with limited space.