Companion Planting
Companion planting is the practice of growing plants near each other that have a mutually beneficial — or sometimes harmful — relationship. TilthIQ's companion planting database helps you make informed decisions about which plants to grow together.
What Companion Planting Does
Different plants can affect their neighbors in several ways:
- Beneficial pairings — one plant repels pests that attack the other, improves soil conditions, attracts pollinators, or provides shade
- Antagonistic pairings — some plants compete for the same nutrients, release chemicals that inhibit neighbors, or attract pests that harm nearby crops
Understanding these relationships helps you design a more productive, lower-maintenance garden.
Good Companions vs. Antagonists
In TilthIQ's companion database, pairings are categorized as:
- Good (shown in green) — the two plants benefit from proximity. Example: Tomatoes + Basil
- Antagonist (shown in red) — the two plants should be kept apart. Example: Onions + Beans
On the Companion Planting page (Planning > Companions), you can browse all known relationships, filter by plant name, and see the reason for each pairing.
Searching for Companions
- Navigate to Planning > Companions
- Type a plant name in the search field (e.g., "Tomato")
- The page filters to show all companion rules involving that plant
- Green rows show beneficial pairings; red rows show antagonistic ones
This is useful when you are planning what to grow in adjacent beds or containers.
Adding New Companion Rules
TilthIQ's built-in database covers the most well-known companion relationships, but experienced gardeners often have their own local knowledge. To add a custom rule:
- Click + Add Rule on the Companions page
- Select the two plants involved
- Choose the relationship type (Good or Antagonist)
- Add a note explaining the benefit or concern
- Save
Custom rules are stored with your account and appear in searches alongside the built-in database.
Warnings on the Planting Details Page
When you view a planting's Details page, TilthIQ checks whether any nearby plantings in the same garden are antagonistic companions. If conflicts are found, a warning banner appears at the top of the page listing which plants are conflicting and why.
This gives you real-time feedback to reconsider placement before it affects your harvest.
Tip: Some of the most impactful companion plantings are simple: plant basil near every tomato, scatter marigolds around the garden perimeter to deter pests, and keep fennel away from almost everything else — it is notorious for inhibiting neighboring plants.