Egg cartons are almost perfectly-made containers for starting seeds indoors. With a dozen (or more) separate pods perfect for individual seeds, and a built-in cover to keep humidity in, egg carton planting is easy, quick, inexpensive. It’s perfect for gardeners on a budget, or who just enjoy finding cool ways to reuse ordinary household items in their gardens. 

How to Start Seeds in Egg Cartons

First, make sure that you have everything else you need. If you’re new to gardening, check out this guide to starting seeds indoors

Choose your Egg Carton

side view of an egg carton planter

While pretty much any egg carton you’ve got sitting in your fridge will work as a planter, I recommend being a little picky. If you’re heading to the grocery store soon, it’s worth checking out the different types. (Yeah, I never thought I’d be closely inspecting egg carton designs, either, but there’s actually a lot of variation.)

Some work a lot better than others. In particular, look for egg cartons with deep, separate pockets for each egg. They’ll hold a little more seed starter mix and give your starts the chance to develop a stronger root system. You also have to consider the material:

Plastic

Plastic egg cartons are my go-to. They’re reusable, easy to clean, and the clear lid allows you to keep a closer eye on your seedlings. However, getting new seedlings out of them to transplant can be a little tricky and requires a lot of care to avoid damaging the roots. 

Cardboard

A lot of gardeners like to use cardboard egg cartons as planters. They’re one-time-use only, but they have the benefit of being biodegradable. That means that instead of transferring your seedlings out of their egg cartons into a larger pot, you can just plant the cardboard pot right into the soil. This can be a lot easier on delicate seedlings. 

Styrofoam

Styrofoam egg cartons also work as a one-time planter. They’re not bio-degradable like cardboard, though. In theory, they can be reused, but they’re not super durable, so don’t expect them to last for multiple seasons. Another reason you might want to avoid them is the possibility of styrofoam leaching harmful chemicals into the seed starting medium – especially when exposed to heat (you’ll probably be having a heat mat on under your egg carton). 

Egg Carton Planting: Step-by-Step

  1. Wash the egg carton
  2. Poke holes in the bottom
  3. Cut the egg carton (optional)
  4. Fill each cell with seed starter mix
  5. Plant your seeds
  6. Cover and place on heat mat

1. Wash the egg carton

Mold and fungus can harm young seedlings, so make sure that your egg carton is clean before you get started. 

2. Poke holes in the bottom

egg carton planter

You’ll need to make sure that each pod has somewhere to drain along the bottom. Using scissors, a knife, or even a toothpick for styrofoam planters, carefully cut a couple of small holes in the bottom of each egg pod to let water drain out. 

3. Cut the egg carton (optional)

I prefer to leave the lids attached to the egg cartons, but you can also cut them off to make it easier to check on your seeds. 

If you’re using a cardboard egg carton, you might also want to cut each individual egg cell out before your plant your seeds. This will make it much easier to plant your seedlings separately when they are ready to be transplanted. 

5. Plant your seeds

egg carton planter with seed starting mix

Press your wet seed starter mix lightly into each cell, making sure to fill it up as much as possible. Check your seed packet to see how deep your seeds need to be planted, and make a little pocket in the center of each cell. Since egg cartons are a lot shallower than most commercially sold seed starter kits, they work best for seeds that like to be planted 1/4 inch deep or shallower. They aren’t great for large seeds, such as peas.

6. Cover and place on heat mat

Place the lid back on your egg carton, and put it on your heat mat. Make sure that you have something under it to catch any water draining out, as you don’t want it to drain directly onto your heat mat. Keep checking your seeds and add water daily to make sure that they don’t dry out. Within a week, you should start to see your seeds sprouting.

Other Tips for Egg Carton Planting: 

  • Egg cartons are generally shallower than specially-made seed trays. You’ll need to watch them a little closer to make sure that they don’t dry out. You’ll also need to be ready to move your seedlings to a bigger pot a little bit sooner, as they’ll outgrow the egg carton quickly. 
  • You might want to put a layer of cardboard or other insulation between the egg carton and the heat mat. Because of how shallow a lot of egg carton planters are, I’ve found that they can get a little too warm for most seeds to germinate.
  • If you’re using cardboard egg cartons, keep a close eye on them. I’ve found that cardboard and biodegradable planters can get over-saturated with moisture and start to break down, or start to grow mold. 
  • Egg cartons do work well for planting, but they have their limits. If you’re not having much success, a specially-made seed starting tray with inserts is usually less than $10, and will give you much more reliable, consistent success.