Great yellow woodsorrel is recognized by its heart-shaped clover-like leaves and delicate yellow flowers that bloom in spring, adding a splash of color to woodlands. These leaves often fold at night, a phenomenon called nyctinasty, which may protect against cold or predation. Thriving in moist, shaded areas, great yellow woodsorrel spreads easily, forming a lush, ground-hugging carpet that adapts to its environment through its resilient rhizomatous root system.
I. Appearance and Characteristics
Oxalis grandis, commonly known as great yellow woodsorrel or large yellow wood sorrel, is an annual plant and herb in the woodsorrel family. It is native to the eastern United States from Georgia north to Pennsylvania and Wisconsin, west as far as Louisiana. It blooms from May to June with yellow flowers and grows in sandy woods or alluvial soils.
II. How to Grow and Care
Sunlight
Great yellow woodsorrel needs medium bright sunlight and should be kept away from the direct bright sun. They enjoy the morning light, so a window facing the rising sun would be a perfect spot as the glass will filter most of harmful light and it will be protected from the intense midday sun. For perfect results, you can even rotate your plant so the flowers would follow the moving sun every couple of weeks. If grown in a garden, partial shade is recommended. Keep in mind that great yellow woodsorrel has a lot of species and cultivars and you should consider the exposure to the sun when choosing your great yellow woodsorrel species.
Temperature
In tropical and temperate regions, great yellow woodsorrel can be quite resilient little plants, even though they are native to South Africa and Brazil. The indoor temperature is quite suited for them, so their optimum is between 16 to 21 ℃. They require moisture, but not excessive so they should be watered every 2-3 days, ideally when the topsoil dries out. If you are growing great yellow woodsorrel in your garden, water them daily only during prolonged droughts or if there is little rainfall in your area.
Watering
Great yellow woodsorrel has medium water requirements, but remember that its bulb does not require sogginess. Water when the top inch of soil is dry and be sure to allow the soil to dry between the waterings. Always ensure that the top 5 cm of the soil is moist after every watering. Rainwater is perfect, but tapwater will work just fine, provided it’s not too hard or too cold.
Soil
Great yellow woodsorrel can be sensitive to overwatering as soggy soil can promote the bulb root rot. This means that you should check for drainage in your garden before you choose your planting site and if you plan on growing them potted indoors, make sure that your container can be drained from the excess of water. Great yellow woodsorrel requires neutral to slightly acidic soil (pH 6.0-6.5). Regarding the soil type, great yellow woodsorrel is not too specific, so a well-drained, store-bought potting mix will work just fine.
Fertilizing
Great yellow woodsorrel is a light feeder and does not require much additional feeding if grown in balanced soil. A balanced, all-purpose liquid fertilizer (half strength) once every couple of months will work just as well as slow-release fertilizer pellets. You should not add any additional nourishment when the plant is in its winter dormancy period. Additionally, when repotting, mix in some organic compost with the soil to give it some extra boost in its sprouting period.
Planting Instructions
Great yellow woodsorrel generally blooms in the summer, so it should be planted during springtime, especially if planted in the garden. As great yellow woodsorrel requires proper drainage, choose locations in your garden in which the rainwater does not pool. Also, take into consideration the different sunlight requirements according to the great yellow woodsorrel species that you plan to plant in your garden. It is smart to plant bulbs and not from the seed, as you are never sure if all seeds will germinate.
Loosen the soil and place the bulbs down about 4 cm and do not worry about on which side you place the bulb, as they will always grow upwards. Great yellow woodsorrel looks stunning and grow well in groups, but be sure to make a bit of space between the bulbs (8 to 10 cm). If grown in pots, place up to 8 bulbs in a 15 cm container, up to 14 bulbs in a 20 cm pot and up to 20 bulbs in a 25 cm pot. Mix in some compost with the extracted soil, return the soil around the bulb and water generously at the end so the soil settles well. They should start sprouting after a couple of weeks.
Pruning
Great yellow woodsorrel requires pruning only when entering their winter dormancy. When the foliage starts to wither, this is the sign that your great yellow woodsorrel is entering its dormant phase. After the leaves turn brown, just remove the dead foliage and don’t worry, this is normal and they will return in the next growing season, which could start anywhere from 2 to 4 weeks. Remember to always disinfect your pruning tools because this minimizes any chances of cross-contamination.
Propagation
The best time for great yellow woodsorrel propagation is during wintertime when the plant is dormant. This is easily done by separating the bulb (or tuber) to create additional plants. Just remove the great yellow woodsorrel from the pot and gently pull the bulbs apart. You can do this by hand. Once separated, just place the bulbs into new containers.
III. Uses and Benefits
Oxalis grandis is used as an ornamental plant in gardens and can be used to attract pollinators to the garden.
