Plant Propagation Basics
Author: Sarah Pounders
Overview
What
could be more exciting than turning one plant into 30 for a plant sale
so that each of your students can take one home? Learning the plant propagation
technique of taking cuttings allows you to do just that, and it allows
students to learn about plant growth, especially factors affecting root
development.
Objectives - Students will:
- Learn about vegetative
(asexual) propagation of plants
- Observe the growth of roots on
cuttings
- Compare different rooting media for cuttings
Standards (Microsoft
Word document)
Materials:
- Stock plants such as coleus, pothos, begonias, or wandering Jew.
You'll need enough so that each student can make two cuttings.
- Clean scissors
- Clean plastic water bottles with the tops cut off.
(Note: Cutting plastic can be tricky. For younger children, adults
should do this part ahead of time.)
- Water
- Moistened soilless potting mix
- Dark colored construction paper
(optional)
Background
Read our how-to guide on Asexual Plant
Propagation to prepare for this lesson.
Laying the Groundwork
Ask students to think about
the following questions:
1. What happens if someone has their toe cut off?
Will it grow back? Will it grow into a new person?
2. What happens if you cut off a stem from a plant? Will it grow back?
What will happen to the cutting?
Exploration
1. Explain to students the concept of vegetative propagation
and how to take a cutting.
2. Give each student two plastic bottles with
the tops removed. Instruct students to fill one of their bottles
with water (call
it “the vase”). Fill the second with moistened soilless mix (call
it “the pot”).
3. Show students how to take stem cuttings
from the stock plant and then have them each take 2 cuttings.
Use clean scissors
and make sure that each cutting is 4 to 6 inches long and
has at least 4 leaves. (For fair comparisons, each student should
use two cuttings from the same stock plant.) Have students remove
the bottom leaves so that you can see the stem. Next, have them
place one cutting in the vase and one in the pot.
Note: The points at which leaves attach to a stem are called
nodes. For many plants, nodes are where roots will first
emerge, so make sure at least one node is below the water or
soil surface.
4. In the vase, only the stem should be submerged in the water.
Students may need to adjust the water level to make sure leaves are
above the surface. In the pot, students should insert the cutting
against the side of the pot so they can easily observe root growth.
5. Monitor the plants daily to check for root growth, and record
any changes. Have students add more water to their vases if it
dips below the original level. They should also make sure the
soilless mix in the pots remains moist.
6. Guide students in using statistics or creating
graphs to document and compare various data such as:
-
Number of
days between potting cuttings and when roots first appear
-
Root data – After 2 to 3 weeks of growth, have students remove the plants from the soil and the water and compare root growth using
theses two methods:
- count and compare the number of roots on each cutting
- measure the roots of plants on the two cuttings
7. Wrap up the activity by giving students time to prepare a
summary of their findings including discussion of their conclusions.
8. Once roots are established, students can pot up their cuttings
to keep in the classroom, take home, or give to
family and
friends. Or, they can grow them for an indoor plant fundraiser (see Cultivating Funds with Indoor Plants).
Making Connections
Extend the exploration by testing the effect of light on root growth.
Divide the class in half. One team can cover their pots with removable,
dark-colored construction paper sleeves while the other team covers
their vases. Does light affect root growth?
Branching Out
-
Take a field trip to a local nursery to watch propagation
practices and equipment in person. If a field trip is not feasible,
contact the nursery to see if a speaker can visit the classroom
for a hands-on demonstration.
-
To reinforce the method of taking
a cutting and to practice communication skills, ask students to
write instructions for the process. The instructions could be written in paragraph form
or as an itemized list, and can include illustrations.
-
Explorers
and plant collectors of the past and present use the technique
of taking cuttings to document and move plants around
the world. Lead students in brainstorming about why
cuttings are useful tools for plant transportation. For background,
see The
Plant Hunters.
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