Overview:
Nasturtium ×sterile (Airy-Shaw) Oefel., commonly known as sterile watercress or the hybrid watercress, is a perennial flowering plant that belongs to the family Brassicaceae. This plant is a hybrid of two other watercress species and is widely appreciated for its spicy leaves and attractive flowers.
Origin:
Nasturtium ×sterile originated in the United Kingdom, specifically in Oxfordshire, where it was first discovered and named by botanist Arthur Roy Clapham in the 1930s. It is a cross between two closely related watercress species, Nasturtium officinale and Rorippa sylvestris.
Common Names:
Sterile watercress is the most common name for Nasturtium ×sterile, but it is also known by other names, including hybrid watercress and Clapham's hybrid watercress. In different parts of the world, it may be referred to as nilgiri or thottakara in Indian cuisine, or simply as watercress.
Uses:
The spicy leaves and flowers of the sterile watercress are edible and have a peppery and tangy flavor that is reminiscent of mustard. They can be used fresh in salads, sandwiches, soups, and sauces, or cooked as a vegetable. The leaves are rich in vitamin C, iron, and calcium. In addition to being used as a food, sterile watercress has been traditionally used to treat various ailments, including coughs, colds, and digestive problems.
General Appearance:
Nasturtium ×sterile has long stems that can trail along the ground or climb up other plants. Its leaves are dark green and pinnately compound, with oval to oblong leaflets that have toothed margins. The plant produces small white flowers with four petals that bloom in clusters from late summer to early fall. The flowers are followed by small, elongated pods that contain the plant's seeds. The plant prefers moist soil and partial shade and can grow up to 60 cm tall.
Light Requirements
Nasturtium ×sterile prefers to grow in a partially sunny environment. This plant requires at least 4-5 hours of direct sunlight every day during the growing season. However, if it is exposed to too much direct sunlight, its leaves may become scorched.
Temperature Requirements
The ideal temperature range for this plant to grow is between 10 to 25 degrees Celsius. At lower temperatures, growth may be stunted, and the leaves may become discolored. When exposed to higher temperatures, the plant may wilt or suffer from leaf burn.
Soil Requirements
Nasturtium ×sterile prefers well-draining soil that is rich in organic matter. The ideal soil pH for this plant is slightly acidic (between 6.0 to 7.0). It is best to provide the plant with a sandy loam soil that is also able to retain moisture. The addition of compost or other organic material can help enrich soil nutrients and support healthy growth.
Cultivation Method for Nasturtium ×sterile (Airy-Shaw) Oefel.
Nasturtium ×sterile (Airy-Shaw) Oefel. is an easy-to-grow and low-maintenance plant that can be propagated by both seeds and cuttings. To grow from seeds, start them indoors about 6-8 weeks before the last expected frost. Once the seedlings are established, transplant them to the desired location, keeping in mind that they like to grow in full sun or partial shade. If you're growing from cuttings, take a 4-6 inch cutting from the stem tip. Place the cutting in a potting mix, keep it moist and in indirect light until roots develop.
Watering Needs for Nasturtium ×sterile (Airy-Shaw) Oefel.
Nasturtium ×sterile (Airy-Shaw) Oefel. plants prefer well-draining soil and require regular watering. However, it is important not to overwater as that can lead to root rot. Water the plants deeply but infrequently and make sure the soil is dry before the next watering cycle. Test the soil for moisture weekly, especially during periods of high heat.
Fertilization for Nasturtium ×sterile (Airy-Shaw) Oefel.
Nasturtium ×sterile (Airy-Shaw) Oefel. plants require fertilization to thrive, but avoid over-fertilizing as it can lead to excessive foliage growth at the expense of flowers. Apply a balanced fertilizer once a month during the growing season (spring to early fall) and follow the dosage instructions on the label. Additionally, you can add compost to the soil to improve soil fertility.
Pruning for Nasturtium ×sterile (Airy-Shaw) Oefel.
Nasturtium ×sterile (Airy-Shaw) Oefel. plants do not require much pruning as they have a bushy and sprawling growth habit. However, if necessary, you can trim back the plants to control their size or shape. Prune the plants in the spring just before the new growth begins. Cut back the stems to a leaf or bud, but leave some stems intact to promote new growth. Deadheading (removing spent blooms) throughout the growing season can also encourage new growth and prolong the blooming period.
Propagation of Nasturtium ×sterile (Airy-Shaw) Oefel.
Nasturtium ×sterile (Airy-Shaw) Oefel. is a hybrid plant that can be propagated through three primary methods: division, seeds, and cuttings.
Division
Division is the process of separating a mature plant into smaller sections and replanting them in other locations to grow new specimens. In the case of Nasturtium ×sterile, the plant can be divided in spring or fall when it is actively growing. The root system of the plant is shallow, making division easy, and the resulting smaller specimens will quickly establish themselves in their new locations.
Seeds
Seeds are another way to propagate Nasturtium ×sterile. The plant produces numerous small, round seeds that are easy to collect and store for future use. The seeds should be sown just below the soil surface and kept moist until they germinate. This can take several weeks, and it is important to keep the seedlings well hydrated until they are established.
Cuttings
Cuttings are a more advanced method of propagation that involves snipping off a section of a healthy plant and placing it in soil or water where it will develop roots. With Nasturtium ×sterile, cuttings should be taken in mid-spring from new growth that is just starting to develop. The cuttings should be dipped in rooting hormone before being planted in a moist growing medium. It can take several weeks for the cuttings to establish roots and begin to grow, so patience is key with this method.
Disease Management
Nasturtium ×sterile (Airy-Shaw) Oefel. is a generally healthy plant with few serious diseases. However, it can fall victim to a few fungal and bacterial infections. Here are some common diseases that affect Nasturtiums, along with some management techniques:
Powdery Mildew
Powdery mildew is a fungal infection that can affect a wide variety of plants, including Nasturtiums. It appears as a white powdery coating on leaves, stems, and flowers. The disease can stunt growth and even kill the plant. To manage powdery mildew, remove infected leaves and spray the plant with a fungicide. Improve air circulation around the plant to decrease humidity and decrease fungal growth.
Bacterial Leaf Spot
Bacterial leaf spot is a disease that affects many plants, including Nasturtiums. The bacterial infection appears as water-soaked, brownish-black spots on the leaves and flowers. The disease can kill young plants and weaken mature ones. To manage bacterial leaf spot, remove infected leaves and spray the plant with a bactericide. Ensure that irrigation water does not splash onto the leaves and avoid overhead watering.
Pest Management
Nasturtium ×sterile (Airy-Shaw) Oefel. is generally pest-resistant, but a few pests can cause problems. The following are some common pests that attack Nasturtiums and some management strategies:
Aphids
Aphids are tiny, soft-bodied insects that can cause curling and yellowing of young Nasturtium leaves. To manage aphids, wash the plant with a strong jet of water to knock the insects off the leaves. You can also use insecticidal soap to get rid of the aphids.
Slugs and Snails
Slugs and snails are common pests that can eat large holes in Nasturtium leaves. To manage slugs and snails, apply diatomaceous earth around the base of the plants. You can also use beer traps, copper strips, and hand-picking to control these pests.
By implementing these disease and pest management techniques, you can keep your Nasturtium ×sterile (Airy-Shaw) Oefel. healthy and thriving.
