Plants From Trash
(Adapted from Recycling: Mining Resources From Trash, Cornell Waste Management Institute)



CONCEPT: What can we do with seeds, other than throw them away?

OBJECTIVE: To observe how plants recycle themselves.

_ water
_ potting soil
_ containers for plants
_ seeds, pits, fruit, or vegetable parts
_ newspaper

KEYWORDS: propagation, exotic

BACKGROUND: Did you know that some of the things you throw away can be grown into attractive houseplants? All you need are a sunny window, some water or potting soil, flower pots or containers, and a little tender loving care.


1. If possible take a trip to the grocery store or fruit market (if you want exotic fruits or vegetables go to the larger grocery stores). If the trip is not possible, the instructor will need to shop for produce.

2. Discuss the different types of propagation. See Plants from Plant Parts, Plants from Seeds, and Plants from Exotic Fruits, which follow:

Plants from Plant Parts:

- White Potato in Soil:
Take a white potato that is showing "eyes" and cut a section that includes an eye (about 1 square inch). Place it in a pot of moist soil, about 2" deep. Keep the plant moist but do not "drown" it. Field potatoes are planted this way.

- Sweet Potato in Water:
In the middle of a sweet potato, stick 3 to 4 toothpicks evenly spaced. Place the potato in a glass of water and put it in a sunny window. Either end can be rooted. Keep the water level high, and after a week or more the potato will usually sprout roots and vine-like stems and leaves.

- Carrot Top in Water:
Cut about 1" - 1 1/2" off the top of 4 to 6 carrots. Fill a shallow bowl 2/3 full of washed pebbles (pebbles help support the tops.) Place the carrot tops over the pebbles. Add water to the level of the pebbles and maintain this level at all times. Soon the tops will sprout pretty foliage.

- Pineapple in Water:
To separate the top from the fruit, hold the fruit firmly with one hand and twist the leafy head with the other. The top should come right off. Remove the lower leaves until the stump is about 1 1/2" long. Put the top in a glass of water and change the water weekly. When roots are 3" to 4" long, transplant to a pot.

Plants from Seeds:

- Avocado Pits:
Remove the pit from an avocado and allow it to dry for 2-3 days. Peel away as much of the onion-like skin as possible. One-third of the way down, inset four toothpicks at regular intervals. The flat end is the bottom and the pointed end is the top.

Put the pit in a glass of water so that 1/2" of water covers the base of the pit. When the roots are 4" long, transplant the pit to a pot and keep it in a bright, warm window. Keep the soil evenly moist at all times.

- Mini-Fruit Trees:
Citrus plants can be grown from seeds removed from oranges, grapefruits, lemons, and tangerines. Soak the seeds overnight in water. Plant 1/2" in moist potting soil. Cover the pot with a plastic bag or a piece of plastic wrap, and put in a warm spot. When the seeds start to grow (in a few weeks), remove the plastic. Keep the plant in a warm, sunny window.

- Beans, Peas, and Lentils:
Soak dried beans, peas, or lentils overnight in warm water. Fill a pot 2/3 full with potting soil. Place three seeds on the top of the soil and cover with 1/2" of soil. Cover the pot with plastic wrap. After the seeds start to grow, remove the plastic. Put the plant in a warm, sunny window, and keep the soil evenly moist. It may be necessary to tie the plants to a small stake as they grow.

- Herbs:
Use anise, caraway, coriander, celery, dill, or fennel seed. Fill a 6" pot 2/3 full with moist potting soil. Place six seeds on top of the soil and cover with 1/2" of soil. Cover the pot with plastic wrap and place in a warm spot. After the seeds begin to grow (3-8 days), remove the plastic and place the plant in a sunny window. After a few weeks, you will have a lovely feathery foliage that can be snipped and used in cooking.

- Peanuts:
Make sure you use fresh, unroasted peanuts. Fill a large, 4" deep plastic bowl 2/3 full with moist potting soil. Shell four peanuts and place them on top of the soil, covering them with 1" of soil. The plant will sprout quickly. In a couple of months small, yellow, pealike flowers will develop along the lower part of the stem. After the flower fades, the ovary swells and starts to grow toward the ground and pushes into the soil. Peanuts will be ready to harvest in about six months.

Plants from Exotic Fruits:

- Mango:
In the center of the mango, there is a large hairy husk with a pit in it. Scrape off all the excess flesh from the husk and gently pry open with a dull knife. The pit is best started in a sphagnum bag. Fill a Ziploc bag with dampened peat moss or sphagnum. Place the pit in the bag and make sure it is completely surrounded by moss. Check every day to make sure the pit is not dried out or rotted from too much moisture. When the roots are 4" long, transplant to a pot that is at least 1" larger than the pit.

- Papaya:
Papayas are not easy to grow because the plants have a tendency to dampen off (die) at about 6" tall. When you cut the papaya open, you will find hundreds of black seeds surrounded by a gelatinous aril (seed covering). To remove the aril, spread some seeds on a paper towel and roll them with your fingers until the aril squashes off. Plant the seeds immediately in a container with sterile potting soil. Give them bottom heat and high humidity until they pass the critical stage of 6" high. Papayas are rapid growers, and once they are established, they will not need a lot of water and fertilizer.

- Tamarind
Tamarind pods look like brown lima beans. The outer shell is brittle and easily peels back, revealing a sticky, brown, pulp. Within this pulp there are five or six shiny black pits. Nick the pits (with a nail file) and soak them until they swell, usually in a few hours. Plant the pits in a container with potting soil and place in a sunny window. Tamarinds are water-loving plants and should never be allowed to dry out. As they grow, pinch them back to make the plant fuller.

(Source: "The Pits", Rare Pit & Plant Council)

Back to Solid Waste Activities Grades K-3

Cornell Waste Management Institute ©1991
Department of Crop and Soil Sciences
Bradfield Hall, Cornell University
Ithaca, NY 14853