You no longer need a vegetable garden (or even a green thumb!) to enjoy food you played a part in cultivating. From scallions to celery, there seems to be no end of possibilities when it comes to regrowing vegetables from food waste. Better yet, you can do it right inside your home.

Romaine lettuce seems like it would be difficult to grow. In reality, it’s anything but and is a great addition to any windowsill garden. All you need to get started is some food scraps, a cup, and water. Yep, that’s it.

Ready to get started? Follow these step-by-step instructions from sustainable living expert Alyssa Barber to learn how to regrow romaine lettuce. You’ll have a homegrown supply in no time.

@newlifestyleabb Excited to have finally finished. 🥬 #gardening101 #gardeningtips #plantlover #lettuce #propagation #howto #ecofriendly #zerowasteliving #foryoupage ♬ Lonely Days – Trees and Lucy

How to Regrow Romaine Lettuce

1. As always, start from scraps. If you’re using store-bought lettuce, Barber says the base end most likely has a sealant on it. Make sure to cut that off the bottom. Your “starter lettuce” will be just the cut base, around two inches tall.

2. Place the lettuce base in a shallow cup or bowl filled with about one inch or less of water. (Most of it should be kept dry, above the water level.) When you have a shallow container, more of the growing plant can be exposed to sunlight.

3. Keep it in a bright, sunny spot. As it grows, Barber recommends changing the water frequently—every day to every other day.

You can stop here and use the lettuce you grow in tacos, wraps, and other meals. Or, if you want a larger supply of lettuce, follow the additional instructions below.

How to Transfer Romaine Lettuce to Soil

While transferring your romaine lettuce to soil is completely optional, Barber says “it’s definitely worth it if you want to get enough lettuce for a salad.”

1. After 1 to 2 weeks of growth in water, check the bottom of the lettuce plant. You should see slender roots sprouting. This means it’s ready to be planted.

2. Plant your growing lettuce in soil and continue to water frequently. You can do this in a container or a garden—whichever you have the space for.

3. Harvest your lettuce whenever you feel you’ve achieved enough growth. Barber’s took about a month.

4. After harvesting your lettuce, Barber says to “give it a really good cleaning, store it in some water to keep it nice and crisp, and put it in the fridge.”

See? Learning how to regrow romaine lettuce might just be the easiest thing you’ve ever done.