Safety First: Understanding Tansy's Toxicity
Before you begin, it is critical to understand that common tansy (Tanacetum vulgare) is a toxic plant. Its volatile oils, particularly thujone, are poisonous to humans and livestock if ingested in sufficient quantities. Early herbal uses are no longer considered safe, and modern herbalists advise against internal consumption. Furthermore, handling the plant can cause skin irritation for some individuals. For these reasons, all harvesting must be done with protective gear.
Protective Gear and Precautions
- Wear Gloves: Use sturdy gardening gloves to prevent direct skin contact with the plant's leaves and stems, reducing the risk of skin irritation or contact dermatitis.
- Wear Long Sleeves: Cover your arms to protect against accidental brushing against the foliage.
- Ventilate Your Work Area: If drying indoors, ensure the space is well-ventilated to avoid inhaling concentrated volatile oils.
- Keep Away from Children and Pets: Store tansy, both fresh and dried, safely away from any who might accidentally ingest it.
- Avoid Composting Seed Heads: Tansy spreads aggressively via seeds and rhizomes. If harvesting after flowering, bag and dispose of seed heads securely to prevent its spread.
Step-by-Step Guide to Harvesting Tansy
1. Proper Identification
Ensuring you have the correct plant is the most important step. Common tansy is often mistaken for the much more toxic tansy ragwort (Senecio jacobaea). Telling them apart is simple if you know what to look for.
- Common Tansy (Tanacetum vulgare)
- Flowers: Bright yellow, button-like, and petal-less flowerheads clustered in a flat-topped spray.
- Leaves: Fern-like and deeply divided into toothed leaflets. Crushed leaves have a strong, pungent odor.
- Stem: Often reddish-brown.
- Tansy Ragwort (Senecio jacobaea)
- Flowers: Yellow, daisy-like flowers with distinct petals (ray flowers).
- Leaves: Irregularly lobed or ruffled, not as finely divided as common tansy.
- Habitat: Commonly found in pastures and along roadsides.
2. When to Harvest
The best time to harvest depends on which part of the plant you intend to use. The oil concentration is at its peak at different times.
- For Leaves: Harvest leaves anytime during the growing season, but the oils are most potent just before the plant begins to flower.
- For Flowers: Harvest the yellow, button-like flowers when they are fully open, typically from July to September.
3. Harvesting Technique
Use clean, sharp scissors or pruning shears to cut the plant material. The technique differs slightly depending on your harvest goals.
- For Leaf Harvest: Snip off individual leaves or small sections of the stem, leaving plenty of foliage on the plant so it can continue to thrive.
- For Flower Harvest: Cut the entire flower head, leaving a few inches of stem attached for easier handling and drying.
4. Drying and Storage
Drying tansy is a crucial step to preserve its properties for later use, such as in insect-repelling sachets or sprays.
- Air-Drying: The most common method involves hanging small bundles of tansy upside down in a warm, dry, and shaded area with good airflow. A garage or attic works well.
- Basket-Drying: For just the leaves, you can strip them from the stalks, place them in a wide, open basket, and fluff them daily to ensure even drying.
- Timing: The drying process takes about one to two weeks, depending on the humidity. The plant material should be completely brittle before storage.
- Storage: Store the dried tansy in an airtight container or paper bag in a cool, dark, and dry location to retain its potency.
Comparison Table: Common Tansy vs. Tansy Ragwort
| Feature | Common Tansy (Tanacetum vulgare) | Tansy Ragwort (Senecio jacobaea) |
|---|---|---|
| Flower Appearance | Yellow, petal-less, button-like clusters | Yellow, daisy-like flowers with distinct petals |
| Leaf Appearance | Finely divided, fern-like, deeply toothed | Irregularly lobed, often ruffled, not as finely divided |
| Stem Color | Often reddish-brown | Variable, may not be reddish |
| Toxicity Level | Toxic, especially if ingested | Highly toxic, especially to livestock |
| Key Repellent Use | Repels flies, ants, and beetles | Can be eaten by livestock when mixed in hay, leading to poisoning |
How to Use Your Harvested Tansy
Once harvested and dried, tansy has several practical applications, all of which should be for external use only. Always prioritize safety and avoid internal ingestion.
- Natural Insect Repellent Spray: Create a strong "tea" by steeping dried tansy leaves in boiling water. After straining, the liquid can be sprayed on plants to repel pests like cucumber and potato beetles. Add a little dish soap to help it adhere.
- Repellent Sachets: Place dried tansy leaves and flowers into small muslin bags to repel moths, fleas, and other insects from closets, pantries, and pet areas.
- Natural Dye: The flowers and leaves of tansy can be used to create colored dyes.
Conclusion
Harvesting tansy can provide a powerful natural resource for pest control and crafts, but it must be done with extreme caution due to the plant's toxicity. By carefully identifying the plant, wearing appropriate protective gear, and following safe harvesting and storage procedures, you can minimize risk and maximize the benefits. Remember, tansy is for external use only, and prioritizing safety is paramount for anyone handling this powerful herb. For more information on plant safety and identification, consult a reliable resource like a university extension office. Further Reading: Common Tansy (Tanacetum vulgare) - MSU Extension
