Nasturtiums are easy-to-grow, edible flowers that thrive in Missouri’s climate. They are valued for their bright blooms, pest-repelling properties, and ability to attract pollinators. These flowers are an excellent choice for container gardens, vegetable gardens, and borders.
1. Plant Overview & Benefits
Scientific Name: Tropaeolum spp.
Common Names: Nasturtium, Indian Cress, Monks’ Cress
Plant Type: Annual flower (reseeds easily)
Sun Exposure: Full sun to partial shade
Soil Preference: Well-drained, moderately fertile to poor soil
Mature Size:
- Bush variety: 12-18 inches tall, spreading up to 12 inches
- Trailing variety: Can vine up to 10 feet
USDA Hardiness Zone: Grown as an annual in Zone 6b-7a
Attracts: Bees, butterflies, and hummingbirds
Resists: Aphids, squash bugs, and other pests
Why Grow Nasturtiums?
- Edible flowers & leaves (peppery, spicy flavor)
- Great companion plant (repels pests, attracts beneficial insects)
- Low-maintenance & drought-tolerant once established
- Excellent for containers & hanging baskets
2. Best Planting Time
When to Plant in Missouri:
- Direct Sowing: After the last frost, usually mid-to-late April in Missouri.
- Start Indoors: 2-4 weeks before the last frost (early March).
- Fall Planting: Nasturtiums grow best in cooler temperatures and can be planted again in late summer (August) for a fall bloom.
Germination Time:
- Seeds sprout in 7-14 days at 55-65°F.
- Nasturtium seeds have a hard outer shell—soaking them overnight (6-8 hours) can improve germination.
Tip: Direct sowing is best—nasturtiums don’t transplant well due to their delicate root system.
3. Site Selection & Soil Preparation
Sunlight Requirements:
- Full sun (6+ hours daily) for best flowering.
- Partial shade is tolerated, especially in hot summers.
Soil Preferences:
- Prefers well-draining, sandy, or loamy soil.
- Thrives in moderately fertile to poor soil—too much fertilizer leads to more leaves and fewer flowers.
- Soil pH: 6.1-7.8 (neutral to slightly alkaline).
Tip: Avoid rich soil or high nitrogen fertilizers—this results in lush foliage but fewer blooms.
4. Planting Instructions
Spacing:
- Bush varieties: 10-12 inches apart.
- Trailing varieties: 12-24 inches apart (or allow them to climb).
How to Plant:
- Sow seeds ½ inch deep directly into the soil.
- Water gently after planting.
- Provide trellises or supports for trailing varieties if growing vertically.
Tip: Plant nasturtiums near vegetable gardens as a trap crop—they attract aphids away from crops like tomatoes, beans, and squash.
5. Watering & Maintenance
Watering Needs:
- Water regularly until plants are established.
- Once mature, nasturtiums are drought-tolerant—water only when soil is dry.
- Avoid overwatering, as soggy soil can cause root rot.
Mulching:
- Light mulching can help retain soil moisture and reduce weeds.
Pruning & Deadheading:
- Deadhead spent flowers to encourage continuous blooming.
- If plants become leggy, trim back by ⅓ to promote bushy growth.
6. Companion Planting Benefits
Good Companion Plants:
Tomatoes – Repels whiteflies and aphids.
Squash & Cucumbers – Protects against squash bugs.
Peppers & Eggplants – Deters aphids and flea beetles.
Beans – Helps deter Mexican bean beetles.
Fruit Trees – Attracts beneficial insects that control pests.
Avoid planting near:
Potatoes – Can attract pests that affect both plants.
Tip: Nasturtiums make an excellent living mulch by shading soil and suppressing weeds.
7. Pests & Disease Resistance
Common Pests:
- Aphids (often attracted to nasturtiums instead of vegetables—trap crop use).
- Caterpillars (may feed on leaves, but don’t usually cause major damage).
Common Diseases:
- Powdery Mildew (common in humid conditions—provide good airflow).
- Root Rot (caused by overwatering).
Disease Prevention Tips:
- Space plants properly to increase airflow.
- Water at the base of the plant to prevent fungal issues.
8. Harvesting & Uses
Harvesting Flowers & Leaves:
- Leaves: Harvest young leaves for fresh salads.
- Flowers: Pick when fully open for culinary or medicinal use.
- Seeds: Can be pickled and used as caper substitutes.
Uses of Nasturtiums:
Culinary Uses:
- Flowers and leaves have a peppery, spicy flavor similar to arugula.
- Used in salads, sandwiches, soups, and garnishes.
- Pickled seeds = “Poor man’s capers”.
Medicinal Uses: - Rich in vitamin C and traditionally used to boost immunity.
Garden Benefits: - Attracts pollinators for increased vegetable yields.
- Repels pests in vegetable gardens.
9. Winter Protection & Overwintering
Will Nasturtiums Survive Missouri Winters?
- No, nasturtiums are annuals in Zone 6b-7a.
- However, they self-seed—new plants may emerge in spring.
Saving Seeds:
- Let seed pods dry on the plant before collecting.
- Store seeds in a cool, dry place for replanting.
- Alternatively, allow plants to self-seed naturally for next season.
10. Missouri-Specific Considerations
Heat Tolerance:
- Nasturtiums can struggle in hot Missouri summers.
- Provide afternoon shade during extreme heat (90°F+).
Late-Season Planting:
- A late summer (August) planting can yield fall blooms before the first frost.
11. Summary of Key Tips
✔ Direct sow seeds after the last frost (April-May).
✔ Full sun to partial shade—too much heat can slow growth.
✔ Avoid rich soil—too much fertilizer = more leaves, fewer blooms.
✔ Water sparingly—nasturtiums are drought-tolerant once mature.
✔ Use as a trap crop to protect vegetables from aphids & pests.
✔ Deadhead flowers for continuous blooming.
✔ Self-seeds easily—expect new plants each year!
