Parietaria officinalis aka Upright Pellitory

Parietaria officinalis is highly adaptable to different soil types, tolerating light sandy soils, medium loamy soils, and heavy clay soils. It prefers well-drained soil with neutral to alkaline pH (6.5-7.5), though it can tolerate mildly acidic conditions. The plant notably thrives on drystone walls and grows well in alkaline soils.

Parietaria officinalis is not particularly demanding regarding humidity levels. As a temperate outdoor plant native to Europe and Western Asia, it adapts well to average outdoor humidity conditions. It tolerates both dry and moist conditions, making it suitable for various climates without special humidity requirements.

Parietaria officinalis generally does not require fertilization. As a wild plant that readily grows on walls, disturbed ground, and various habitats with minimal nutrients, it is adapted to survive without supplemental feeding. If growing in very poor soil, an occasional application of general-purpose fertilizer during the growing season may encourage more vigorous growth, but it is not necessary for the plant's survival.

Parietaria officinalis can be propagated by seed or division. Seeds can be sown in spring or autumn in a cold frame, with seedlings transplanted in summer, or sown directly in situ. Division is very easy and should be done in spring—larger divisions can be planted directly into permanent positions, while smaller divisions should be potted and grown in light shade until established. Note that the plant is dioecious, so both male and female plants are needed for seed production.

Parietaria officinalis typically reaches 20-70 cm (8-28 inches) in height, occasionally growing up to 100 cm (40 inches) in ideal conditions. The plant has a moderate growth rate and spreads via underground rhizomes to form clumps approximately 50 cm wide. It produces erect, cylindrical stems that are reddish and succulent, with little branching. As a perennial herb, it returns year after year, gradually expanding its spread through rhizomatous growth.

Parietaria officinalis is exclusively an outdoor plant, thriving in USDA hardiness zones 4-9 and UK hardiness zone H5. Native to temperate Europe, Western Asia, and the Caucasus, it prefers moderate temperatures and can handle light frost but may need protection in severe winters. The plant grows best in full sun to partial shade and is particularly well-suited to growing on walls, in rock gardens, or naturalized in wild areas of the garden.

Parietaria officinalis prefers moderate temperate conditions and is hardy in USDA zones 4-9, tolerating winter temperatures down to -30°F (-34°C) in zone 4. The plant handles light frost well but performs best in moderate temperatures typical of its native temperate European climate. In hotter regions (zones 8-9), it benefits from afternoon shade to protect from intense heat.

Parietaria officinalis flowers from June to October, producing small, inconspicuous greenish flowers. The plant is dioecious, meaning individual plants are either male or female, and both sexes must be present for seed production. The flowers are wind-pollinated rather than insect-pollinated, which accounts for their small, unshowy appearance. The pollen is notably allergenic and is one of the earliest and most active hay fever allergens.

Parietaria officinalis is generally a robust plant with few serious pest or disease problems. As a member of the nettle family that readily colonizes walls and disturbed ground, it has evolved natural resilience. No significant pests or diseases are commonly documented for this species in botanical literature. Its main concern is not vulnerability to pests, but rather its highly allergenic pollen, which can cause hay fever in sensitive individuals.

Parietaria officinalis is wind-pollinated, typical of plants in the Urticaceae (nettle) family. The small, inconspicuous greenish flowers do not need to attract insect pollinators, relying instead on wind to carry pollen from male plants to female plants. The plant is dioecious with separate male and female plants, and the pollen produced is abundant and highly allergenic—it is one of the earliest and most active hay fever allergens in temperate regions.

Parietaria officinalis is edible but not particularly palatable, earning an edibility rating of 2 out of 5. Young leaves and shoots can be consumed raw or cooked, with tender shoots suitable for adding to mixed salads. The plant has been used as a minor wild food source, though it is not considered a choice edible. While the plant tissue is non-toxic and safe to eat, individuals with hay fever or pollen allergies should exercise caution.

Parietaria officinalis has been valued for over 2,000 years for its medicinal properties, earning a medicinal rating of 3 out of 5. The whole herb, gathered when flowering, is used as a diuretic, cholagogue, demulcent, laxative, and vulnerary. Primary applications include treating kidney and bladder stones, urinary complaints (cystitis, nephritis), chronic coughs, and as an external poultice for wounds and burns. Important caution: It should not be prescribed to people with hay fever or other allergic conditions, as the pollen is highly allergenic.

Parietaria officinalis has minimal non-food, non-medicinal uses, earning a rating of 1 out of 5. Historically, the whole plant has been used to clean windows and copper containers, taking advantage of the plant's natural cleaning properties. This represents a traditional household use, though it is rarely practiced in modern times.

Upright Pellitory presents a moderate level of care, which allows plant enthusiasts with some experience to expand their skills and knowledge.

Upright Pellitory’s native range is Western Europe to Western Asia and the Caucasus.

Upright Pellitory should be watered regularly, allowing the soil to dry out between waterings.

To ensure optimal growth, the Upright Pellitory prefers bright diffused light for 6-8 hours each day. Insufficient light can result in slow growth and leaf drop, so it's important to find a well-lit location for this plant. Place it near a window, within a distance of 1 meter (3 feet), to enhance its potential for thriving.

The toxicity level of this plant has not been officially confirmed by Ploi. If there is a possibility of ingestion of plant material with an uncertain toxicity by you, a family member, or a pet, it is advisable to seek the assistance of a medical professional.

During the wintertime, it's common for Upright Pellitory to go dormant and their growth may slow down, so waterings should be spaced out more.