Polygala sanguinea — a medium houseplant, prefers full sun light
SPECIMEN · FROM THE LIBRARY
Polygala sanguinea

Polygala Sanguinea

Updated · 61 observations
ON THIS PLANT

Polygala sanguinea, known as purple milkwort, field milkwort, or blood milkwort is an annual plant in the Polygalaceae (milkwort) family. It is native to central and eastern North America.

A note from PlantMom

Purple milkwort is fairly disease-resistant and generally not susceptible to illnesses. However, it can be affected by pests and diseases that occur nearby. These infections are typically mild. Regarding care, this plant needs moderate maintenance. It should be pruned regularly to preserve a neat appearance and healthy growth. Fertilizing can also encourage flowering. Purple milkwort is suitable for anyone with outdoor space, like a garden or patio, and does not demand extensive gardening experience. It may require more attention when grown indoors.

— PlantMom
CARE GUIDE

How to keep Polygala Sanguinea.

Light

Purple milkwort thrives with maximum sun exposure, which supports healthy growth. While it comes from habitats with abundant sunlight, it can still tolerate somewhat reduced light. Keep in mind that too much or too little light can change its growth and may cause harm.

Water

Purple milkwort flourishes in moist environments and needs consistently moist soil without becoming waterlogged. Watering once a week is typically sufficient to meet its hydration needs. Although it is mainly grown outdoors, purple milkwort benefits from natural rainfall and seasonal changes, which are crucial for its active growth period.

Temperature

Purple milkwort is native to temperate habitats and does best at temperatures of 68–95 °F (20–35 °C). For optimal growth, keep the air around the plant within that range, adjusting it as the seasons change.

Fertilizer

When most of Purple milkwort’s flowers have fully opened, you should resume fertilizing. At the time the blooms are at their peak, fertilize again every three to four weeks, as weather allows. Once Purple milkwort begins producing fewer new flowers, stop fertilizing; there is no need to feed the plant when it can no longer form more blooms.

Pruning

Purple milkwort is known for its vibrant purple flowers and compact growth habit. To maintain its health and appearance, it's beneficial to prune the plant from early to late spring. This process removes any dead stems and improves air circulation, resulting in more abundant blooms. Additionally, regular trimming after the flowering period helps shape the plant and gets it ready for the next growth cycle.

CHARACTERISTICS

Botanical profile.

Plant Type
Herb
Life Cycle
Annual
Genus
Polygala
Family
Polygalaceae
Hardiness Zone
4-8
Mature Height
10 cm to 30 cm
Mature Spread
10 cm to 20 cm
Leaf Color
Green, Dark Green
Leaf Type
Semi-evergreen
Flower Color
White, Pink, Purple, Red
Flower Size
2.54 cm
Bloom Time
Summer
Planting Time
Spring, Summer, Autumn
Harvest Time
Late summer, Early fall, Mid fall
Native Area
Georgia
ALSO KNOWN AS

Other names.

en Common polygala en Field milkwort en Purple milkwort en Rose milkwort en Blood milkwort en Blood polygala en Blood-red Milkwort en Blood-colored milkwort
FREQUENTLY ASKED

Reader questions.

How should I water my Purple milkwort?

To water Purple milkwort, there are several options available. You can use a garden hose with a spray nozzle, a watering can, or any other common watering tool. Purple milkwort is not too particular about the water source, as it can survive with rainwater, tap water, or filtered water. However, it is advisable to avoid watering overhead, as it can damage the leaves and flowers and potentially result in disease. A drip irrigation system is often the best choice for watering this plant since it distributes water evenly and directly to the soil. On the other hand, if you have a container-grown Purple milkwort, you can use a cup, watering can, or simply pour water from your tap directly onto the soil.

What are the sun requirements for Purple Milkwort?

Purple Milkwort requires a significant amount of sunlight to thrive, ideally above 6 hours of direct sunlight for full sun conditions and about 3-6 hours of sunlight for partial sun conditions. It's important to observe the movement of sunlight in your garden to find the perfect spot that offers a balance of light and shade, ensuring the plant's health. While Purple Milkwort originates from environments with abundant sunlight, it can tolerate slightly less light. However, both excessive and insufficient light exposure can adversely affect its growth.

What is the ideal temperature range for Purple milkwort?

Purple milkwort thrives in temperate environments, with an ideal temperature range between 68 to 95 °F (20 to 35 °C) for optimal growth. It's important to adjust the surrounding temperature of the plant accordingly with seasonal changes to ensure it remains within this range.

What should I do if I give my Purple milkwort plant too much or too little water?

If you notice that your Purple milkwort lacks moisture, the solution is simple: water it more regularly. However, overwatering can be much more serious if not caught early. Overwatered Purple milkwort can develop diseases that lead to its decline and death. To prevent this, it's important to choose a suitable location with ample sunlight to dry the soil and good drainage to prevent waterlogging. If you have overwatered your potted Purple milkwort, you may need to consider changing to a new pot with better drainage. When repotting, use loose soils and ensure the new pot drains efficiently.

How do artificial lights support indoor plant growth?

For indoor plants, adequate lighting is essential, especially when natural sunlight is insufficient. In such cases, artificial lights provide a crucial alternative, promoting faster and healthier plant growth. LED lights are commonly used because they can be customized to supply specific light wavelengths needed by plants. The amount of artificial light required varies depending on the plant's needs: full sun plants need 30-50W/sq ft, partial sun plants require 20-30W/sq ft, and full shade plants need 10-20W/sq ft. The light source should be placed 12-36 inches above the plant to mimic natural sunlight, and most plants benefit from 8-12 hours of light per day.

Does Purple milkwort require special frost protection measures during winter?

Purple milkwort has strong cold resistance and usually does not require special frost protection measures during winter. However, if winter temperatures are expected to drop below -30°C, it's important to provide cold protection by covering the plant with materials such as soil or straw. Moreover, watering the plant abundantly before the first freeze in autumn is recommended to keep the soil moist and prevent drought and water scarcity.

How often should I give water to my Purple milkwort?

Purple milkwort requires regular watering throughout the growing season. In spring, it should be watered once a week. As the season progresses and it gets warmer, watering may need to increase to two or three times a week. However, overwatering can be harmful to the plant. Regardless of watering frequency, ensure that the soil remains moist but not wet. Watering Purple milkwort in a pot is slightly different. Due to the soil in pots drying out faster, watering frequency needs to be increased. In most cases, container-grown Purple milkwort should be watered a few times per week, compared to just once a week for a plant in the ground.

What symptoms indicate insufficient light for Purple Milkwort?

When Purple Milkwort is grown indoors with inadequate light, it may display several symptoms indicative of light deficiency. These include smaller new leaves, leggy or sparse growth, faster leaf drop, slower or halted growth, and paler new leaves. Chlorosis, where leaves turn yellow due to a breakdown of chlorophyll, sunscald characterized by pale, bleached areas on the plant, leaf curling as a response to intense sunlight, wilting due to loss of water through transpiration, and leaf scorching marked by brown, dry edges on leaves, can also occur with inappropriate light exposure.

How does Purple milkwort react to low temperatures?

Purple milkwort is cold-tolerant and performs best when temperatures are kept above 20°C. During winter, it should be protected to ensure temperatures stay above 0°C. If temperatures fall below -30°C, you might not notice changes during the winter, but there might be a decrease in sprouting or even an absence of sprouting during spring. In spring, it's advised to remove any parts of the plant that have failed to sprout.

How much water does my Purple milkwort plant need?

To determine the appropriate amount of water for your Purple milkwort, there are a few options. One method is to feel the soil and water until the first six inches are moist. Another option is to use a standard measurement, such as two gallons per week, adjusting for temperature and soil moisture. However, be cautious not to overwater if your plant requires less. For container-grown Purple milkwort, ensure all soil layers are moistened and check for moisture by sticking your finger in the soil or observing excess water drainage.

What solutions can improve light conditions for indoor and outdoor Purple Milkwort plants?

To enhance growth, gradually move Purple Milkwort plants to locations with at least 6 hours of direct sunlight daily, using a south-facing window for indoor plants and ensuring curtains remain open. If the plant is large or not easily movable, supplementing with artificial light such as desk or ceiling lamps for at least 8 hours daily, or using professional plant grow lights, can help. Outdoors, plants should be gradually moved to sunnier spots to adapt without risking sunburn. For plants in the ground, reducing obstructions by pruning trees or transplanting during dormant periods to locations with better sunlight and drainage can significantly improve light exposure. It's crucial to understand that while parts of the plant that suffered due to insufficient light might not recover, new growth will be healthy with improved light conditions.

What should be done if Purple milkwort is exposed to high temperatures?

During summer, it's critical to ensure that temperatures around Purple milkwort are kept below 35°C. Exposure to temperatures over 38°C can result in lighter-colored leaves, a tendency for the leaves to curl, susceptibility to sunburn, and, in severe cases, the entire plant may wilt and dry. To mitigate these issues, trim away the sunburned and dried parts, move the plant to a shaded location, or use a shade cloth to protect it from the midday and afternoon sun. Additionally, water the plant in the morning and evening to keep the soil moist.

PLATES
Polygala sanguinea leaf
PLATE 01 · leaf
Polygala sanguinea leaf
PLATE 02 · leaf
Polygala sanguinea flower
PLATE 03 · flower
Polygala sanguinea flower
PLATE 04 · flower
ALSO IN THE LIBRARY

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