5 Perfect Companion Plants to Start Now for Your Fall Garden

As you prepare your garden for fall vegetables, don't overlook the opportunity to integrate companion plants that can enhance your harvest success. Mid-to-late July is the perfect time to sow these beneficial companions alongside your fall crops.

As a biologist and gardener, I've found that strategic companion planting creates a more resilient garden ecosystem that reduces pest pressure and increases overall productivity. The following five companion plants can be started right now to provide maximum benefit for your fall garden.

1. Calendula: The Versatile Protector

Calendula (Calendula officinalis), also known as pot marigold, is one of the most useful companion plants you can add to your fall garden.

Benefits for Your Fall Garden:

• Repels aphids and thrips that commonly attack fall brassicas
• Attracts beneficial insects including pollinators and predatory insects
• Root exudates improve soil microbiology
• Provides cheerful color as other plants fade
• Edible petals add color to fall salads

Planting and Growing Tips:

• Direct sow seeds 1/4 inch deep and 8-12 inches apart
• Germinates quickly, usually within 5-10 days
• Blooms approximately 45-50 days after planting
• Prefers full sun but tolerates partial shade
• Continues flowering after light frosts

Calendula's pest-repelling properties make it an excellent companion for fall broccoli, cabbage, and kale. Plant it throughout your brassica beds rather than just at the borders for maximum effectiveness. Research at the University of California has demonstrated that calendula's sticky stems and strong scent effectively deter aphids while its bright flowers attract hover flies that prey on cabbage-loving pests.

2. Nasturtiums: Beautiful Trap Crops

Nasturtiums (Tropaeolum majus) serve as sacrificial "trap crops" that attract pests away from your valuable vegetables while adding vibrant color to the fall garden.

Benefits for Your Fall Garden:

• Strongly attracts aphids away from brassicas and other fall crops
• Deters squash bugs, cucumber beetles, and some caterpillars
• Flowers attract pollinators to ensure good fruit set on late squash
• Entirely edible - both flowers and leaves add peppery flavor to salads
• Trailing varieties provide living mulch that reduces soil splash and moisture loss

Planting and Growing Tips:

• Soak seeds overnight to improve germination
• Direct sow 1/2 inch deep and 10-12 inches apart
• Germinates in 7-10 days
• Blooms approximately 35-45 days after planting
• Prefers poorer soil - avoid excessive nitrogen which reduces flowering

Nasturtiums excel as companions for cucumbers, squash, and pumpkins. Their sprawling growth habit works well around the base of these plants, and their ability to attract aphids away from your crops makes them valuable sacrificial plants. I've consistently observed that aphids colonize nasturtiums while leaving nearby vegetables untouched.

3. Dill: The Beneficial Insect Magnet

Mid-summer is an excellent time to sow dill (Anethum graveolens), which performs beautifully in the cooler temperatures of fall.

Benefits for Your Fall Garden:

• Attracts parasitic wasps that control cabbage worms and other caterpillars
• Draws in ladybugs and lacewings that prey on aphids
• Improves flavor of nearby cabbage family crops
• Provides fresh herb harvest into fall
• Self-seeds readily for next year's garden

Planting and Growing Tips:

• Direct sow seeds 1/4 inch deep
• Thin to 6-8 inches apart
• Germinates in 7-14 days
• Reaches full size in approximately 40-50 days
• Prefers full sun but tolerates light shade in hot climates
• Allow some plants to flower for maximum beneficial insect attraction

Dill makes an outstanding companion for fall brassicas including broccoli, cabbage, and Brussels sprouts. Research published in the Journal of Economic Entomology has shown that dill flowers are particularly effective at attracting Ichneumonid wasps, which parasitize the caterpillars that commonly damage fall brassica crops.

4. Cilantro: Dual-Purpose Fall Companion

Cilantro (Coriandrum sativum) actually grows better in fall than summer, as it's prone to bolting in high heat.

Benefits for Your Fall Garden:

• Attracts beneficial predatory insects including syrphid flies and parasitic wasps
• Repels some harmful insects including aphids and spider mites
• Improves growth of nearby leafy greens
• Provides fresh herb harvest well into fall
• Grows more lush and full in cooling temperatures

Planting and Growing Tips:

• Direct sow seeds 1/4 inch deep
• Thin to 6 inches apart for full plants
• Germinates in 7-10 days
• Ready for harvest approximately 30-35 days after planting
• Choose "slow-bolt" varieties for extended leaf production
• Succession plant every 2-3 weeks for continuous harvest

Cilantro performs exceptionally well when interplanted with fall leafy greens including lettuce, spinach, and Asian greens. Studies from the University of California have demonstrated that cilantro flowers attract beneficial insects that prey on the common pests of fall greens, while its distinctive aroma can help mask the scent cues that pests use to locate host plants.

5. Borage: The Pollinator Powerhouse

Borage (Borago officinalis) is often overlooked but offers numerous benefits when planted in mid-summer for fall gardens.

Benefits for Your Fall Garden:

• Attracts a remarkable diversity of pollinators, especially bees
• Improves the growth and flavor of nearby tomatoes and squash
• Adds trace minerals to the soil through its deep taproot
• Produces edible blue flowers that taste like cucumber
• Continues blooming after light frosts
• Self-seeds readily for future gardens

Planting and Growing Tips:

• Direct sow seeds 1/4 inch deep
• Thin to 12-18 inches apart (plants get large)
• Germinates quickly, usually within 5-7 days
• Blooms approximately 50-60 days after planting
• Prefers full sun but tolerates partial shade
• Once established, requires minimal care

Borage partners beautifully with fall-planted strawberries, late tomatoes, and winter squash. Its profuse blue flowers are irresistible to pollinators, ensuring better fruit set on late-season crops. Research at the University of Sussex has shown that borage flowers produce more nectar than many other garden plants, making them particularly valuable for supporting beneficial insects.

Strategic Placement for Maximum Benefit

For companion planting to work effectively, strategic placement is essential:

1. Interplant Rather Than Segregate:
   Intersperse companion plants throughout your vegetable beds rather than relegating them to borders only. This proximity maximizes their protective effects.

2. Consider Height and Spread:
   Place taller companions like dill where they won't shade sun-loving fall crops. Trailing plants like nasturtiums work well around the base of larger vegetables.

3. Group Compatible Plants:
   Create polyculture groups of vegetables and companions that share similar water and sunlight needs.

4. Allow Some to Flower:
   While you may harvest herbs like cilantro and dill for culinary use, allow some plants to flower to attract beneficial insects.

Planting and Maintenance Tips for Summer-Sown Companions

Starting companions in mid-to-late July requires some special considerations:

1. Keep Soil Consistently Moist:
   Summer heat can quickly dry out soil, so water newly seeded areas lightly but frequently until germination occurs.

2. Consider Afternoon Shade:
   During the hottest days of summer, providing temporary shade during peak afternoon heat can improve germination rates.

3. Use Fresh Seed:
   For best germination in challenging summer conditions, use fresh seed rather than older stored seed.

4. Plant Slightly Deeper:
   In summer heat, planting seeds about 25% deeper than spring recommendations helps them access moisture.

Conclusion

By incorporating these five companion plants into your fall garden plans now, you're setting the stage for a more productive, resilient garden with fewer pest problems. Their beautiful flowers will also extend the aesthetic appeal of your garden into fall while providing valuable ecosystem services.

The cooling temperatures ahead are perfect for establishing these companions, and they'll reach their prime protective capacity just when your fall vegetables need them most. As beneficial insects become scarcer in late summer and fall, these flowering companions become even more valuable for attracting and retaining the garden allies you need.

Mid-July to early August is the sweet spot for starting these companions—don't miss this opportunity to enhance your fall garden naturally!

What companion plants have you found most effective in your fall garden? I'd love to hear about your experiences in the comments below!