Companion Planting
Sabine Harvey sharvey1@umd.edu
College of
Agriculture and
Natural Resources
What is Companion Planting?
• The establishment of two or more plant
species in close proximity so that some
cultural benefit is derived
History
• Pliny the Elder, 23-79 AD
• Three Sisters
• Sensitive crystallization test? Biodynamics.
Be Aware: Allelopathy
• Greek: Allelon = “of each other”, pathy = “to
suffer”
• Broccoli and cabbage
• Marigolds
• Crabgrass
• Sunflowers
• Black Walnut
Various Mechanisms
• Biodiversity/beneficial insects
• Pest control (biochemical, trap crops)
• Symbiotic relationship
• Increased crop diversity
• Physical interaction (shade, fast-slow growing)
Beneficial Insects
• Any plant in the aster, mint or carrot family
• Flowers during entire season
Good Guys:
Predators
Good Guys:
Parasitoids
Pest Control, Maybe
• Usually heavily scented herbs
• Different color
• Pest repellent or trap crop
Nasturtiums
• Deter pests from beans, cabbages and squash
family
• But in some trials they attracted pests
• AND they grow better in poor soil
Marigolds
• Tagetes patula – French marigold
• Controls root-knot nematodes
BUT
• Can also be allelopathic: beans, cabbages
Physical Interactions
• Three sisters: perfect example
How to Start?
• Pick your favorite veggies
• Do you have the space?
• Avoid planting together:
plants of same family (except cabbages)
plants that use the same nutrients
plants with similar root zones
Beans and Peas
•
•
•
•
Potatoes
Corn, squash, cucumber
Summer savory, dill
Pole beans create shade for lettuce
• Not with onion family or marigolds
Cabbage Family
• Potatoes
• Any strong smelling plant
• Use space between plants
• Not with marigolds
Carrots
• Grows well with almost anything
• Onion family
• Keep away from dill, parsnips
Lettuce
• Plant below/behind tall crops in summer
• Onions and roots crops
• Anything
• Sensitive to decaying rye
Onion Family
• Good with anything, except legume family
• Don’t forget garlic!
Potatoes
• Beans
• Plant with fast growing spring veggies
• Do not plant with tomatoes, raspberries,
squash family
Squash Family
• Beans and corn
• Radishes!
• Nasturiums?
Tomatoes
• Onion/garlic or strong smelling herbs
• Asparagus?
• Basil!
• Very sensitive to black walnut
• Not near fennel, potatoes or corn
Think Twice!
• Amaranth
• Comfrey: Symphytum officinale, Russian comfrey Symphytum x uplandicum
• Flax
• Tansy
Happy Gardening!
Sources
• Companion Planting, Susan Mclure, Rodale
Press.
• Great Garden Companions, Sally Jean
Cunningham, Rodale Press
• Companion Planting: Basic Concepts and
Resources, ATTRA Publication
Resources
• Grow It! Eat It!
http://www.extension.umd.edu/growit
– We have all types of practical food gardening tips and
information. Check out our popular blog!
• Home and Garden Information Center
http://www.extension.umd.edu/hgic
– Here you will find factsheets, photos, and videos. You
can also subscribe to the free monthly e-newsletter.
– We answer gardening questions 24/7…just click
“Ask Maryland’s Garden Experts”
• Maryland Master Gardener Program
http://www.extension.umd.edu/mg
– Consider becoming a trained MG volunteer!
This program was brought to you by the
Maryland Master Gardener Program
Kent County
University of Maryland Extension