Growing Conditions for Toothache Plant

The toothache plant, also known as Spanish Needle or Bidens pilosa, is a medicinal herb that has long been used for tooth pain relief. With its bright yellow flowers and soft, fuzzy leaves, it is also grown as an ornamental plant. To grow toothache plant successfully, it is important to understand and provide the right growing conditions.

Sun Requirements

Toothache plant thrives in full sun. This means it needs at least 8 hours of direct, unfiltered sunlight per day. Native to tropical and subtropical regions, the toothache plant craves bright light.

Insufficient sunlight will result in diminished flowering and poor plant growth. The stems will become long and leggy as the plant stretches to reach the sun. The foliage will be sparse.

Ideally, plant toothache in a spot that receives sunlight for most of the day. A location on the south or west side of a building is perfect. Be sure no large trees or structures shade the area for long periods.

Morning sun is essential. The rays at dawn are least intense, allowing leaves to warm gradually. Afternoon sun is appreciated too.

Soil Needs

Since toothache plant is an annual in most growing zones, the plant has a short period to establish itself. It requires well-draining soil to thrive.

To amend garden beds before planting, mix in copious amounts of compost. Compost improves drainage while adding valuable nutrients.

If planting in containers, use a commercial potting mix blended for annuals. Include a slow-release fertilizer to provide extra nutrients.

The soil pH should be between 6.0-7.0 for optimal growth. Test kits are inexpensive and provide guidance for correcting pH before planting.

Watering Habits

Toothache plant needs consistent moisture to look its best. But soggy soil can be problematic.

Water toothache plant when the top inch of soil feels dry. Use your finger to test soil moisture. Schedule watering for early morning to allow leaf surfaces to dry out during the day.

In very hot climates, toothache may require daily irrigation. Container grown plants will need more frequent watering than in-ground specimens. Install drip irrigation for convenience.

If soil remains damp for days, increase drainage by amending with perlite or small gravel. Let the soil dry out between waterings.

Reduce watering as cooler weather arrives. Plants do not require much water while dormant.

Temperature Tolerance

Since toothache plant originates in tropical zones, it is extremely sensitive to cold temperatures. Plants will suffer damage once nighttime temperatures drop below 50°F.

In zones 8-11, toothache will thrive as a warm-season annual. Sow seeds after the last expected frost when soil warms to at least 65°F.

Farther north, start seeds indoors up to 8 weeks before the final frost. Harden off seedlings before transplanting them outside. This gives plants a head start on the short growing season.

As autumn approaches, harvest leaves to dry or extract oils. Pull up the entire annual plant after the first light frost blackens the foliage.

In zones 9-11, toothache may perennialize in sheltered microclimates. Mulch heavily around the roots if attempting to overwinter the plant.


Toothache plant is easy to propagate from both seeds and cuttings. Growing new plants from mature ones ensures they will be true to type.

Start seeds indoors 8-10 weeks before last spring frost. Barely cover seeds with seed starting mix. Keep the soil consistently moist and warm (70-80°F) until sprouts emerge.

Once seedlings have 2-3 true leaves, transplant into the garden after hardening off for 5-7 days.

For cuttings, use 3-4 inch pieces of stem tips taken from an established plant. Remove leaves from the lower half of each cutting. Dip the end in rooting hormone for faster root development.

Insert cuttings in moist potting mix leaving 1-2 nodes above the soil. Enclose in a plastic bag or propagation dome to retain humidity. Rooting takes 1-3 weeks.

Growth Habit

Toothache plant grows quickly once established. It reaches a mature height of 2-3 feet with a similar spread.

Pinching back the main stem and side shoots will make the plant bushier. Continual harvesting of leaves and flowers also keeps plants compact and promotes branching.

In warm climates, toothache plant may bloom year-round. The yellow flowers appear at the ends of branches in clusters of button-like discs. Deadheading spent blooms prolongs the display.

Nutritional Needs

To fuel rapid growth and flowering, toothache plant needs consistent feeding. Apply a balanced liquid fertilizer every 2-4 weeks during the growing season.

Organic options like fish emulsion, compost tea, or liquid kelp provide trace nutrients. For quicker greening, use a nitrogen-heavy formula.

When growing in soil, work compost or aged manure into beds before planting. Topdress containers with worm castings or organic granular fertilizer. This provides steady nutrition release.

Watch for yellow lower leaves, an indicator plants need more nitrogen. Deficiencies in phosphorus and iron also cause yellowing. Adjust fertilizer to correct.

Potential Problems

Toothache plant suffers few serious problems when grown under ideal conditions. Potential issues to watch for include:

  • Powdery mildew – Distinctive white fungal coating on leaves. Improve air circulation and reduce watering.
  • Aphids – Green, red, black, or white sap-sucking insects on leaves and flowers. Knock off with a strong spray of water or use insecticidal soap.
  • Spider mites – Tiny pests that form webs and stipple leaves. Wipe or spray away with neem oil treatments.
  • Root rot – Roots turn brown and mushy in overly damp soil. Allow soil to dry between waterings.

With proper site selection, soil preparation, and care, toothache plant is not difficult to cultivate. Pay close attention to its sun and water requirements for robust growth and plentiful flowers.

Medicinal Uses

In addition to being an attractive ornamental plant, toothache plant has long been used to relieve dental pain and other ailments. All parts of the plant contain medicinal compounds.


The leaves of toothache plant contain flavonoids, saponins, and tannins that reduce inflammation and pain. To make a poultice for toothaches, crush fresh leaves and pack directly on the affected tooth and gum area. You can also chew the leaves or use the juice directly in the mouth. The leaves also have antiseptic properties to fight infection.

Tea made from the dried leaves has antioxidant, diuretic, and laxative effects. It is taken internally for constipation or urinary tract infections.


The yellow flowers can also be used as a poultice or chewed directly for tooth pain relief. Dried flowers infused into oil make an antifungal skin ointment to treat ringworm, athlete’s foot, and other fungal infections.


The roots contain the most potent medicinal compounds. Toothache plant gets its common name from the roots’ ability to dramatically ease dental pain and inflammation.

Fresh root poultices are commonly used by indigenous peoples to treat cavities and infections. The roots have antibiotic, anesthetic effects to numb pain.

Dried, powdered roots are used in various oral health products today. The roots are also valued for their antidiabetic properties.

Growing Toothache Plant

With its brilliant yellow blooms and useful medicinal properties, toothache plant is a great addition to gardens in warm climates. Follow these key growing conditions for success:

  • Full sun exposure
  • Well-draining soil
  • Moderate watering when soil is slightly dry
  • Protection from frost and cold
  • Frequent fertilization
  • Prune for compact, bushy growth

When provided with its ideal environment, toothache plant generously rewards gardeners with an abundance of cheery flowers and powerful natural medicine.