What is the appropriate planting density for purple loosestrife?

1. Purple loosestrife (Lythrum salicaria) is highly vigorous and can be managed extensively, but a location with ample sunlight and good ventilation should be chosen. In open-ground cultivation, it is mostly planted in shallow-water areas and wetlands of garden waterscapes by park lakesides; in courtyards it can be grown in pots. The growing soil must be given an appropriate amount of decomposed chicken manure or cake fertilizer.

2. After purple loosestrife is planted until the rows close, cultivate and weed 3 to 4 times each year. Apply nitrogen fertilizer or compound fertilizer once each in spring and summer, and topdress once with compost or barnyard manure after autumn. Keeping the soil constantly moist is the most critical measure for growing purple loosestrife well. During the growing season, promptly remove weeds and water moss; before flowering and during the flowering period, topdress with potassium dihydrogen phosphate two to three times. Keeping the soil constantly moist can promote vigorous plant growth.

3. In late October the above-ground parts of purple loosestrife gradually wither; use pruning shears to cut off the above-ground clumps and leave them to overwinter naturally in the open ground. Potted plants must be moved into a low-temperature cold shed to overwinter; throughout winter the potting soil must be kept moist, and the temperature is best controlled at 0°C to 5°C, so as to prevent early sprouting in winter. Generally divide and replant once every two to three years. Glass, germinates in about 20 days

Key points for garden maintenance of aquatic plants

Aquatic plants refer to a class of plants whose bodies live partly or entirely for long periods in water or moist soil and which can complete their reproductive cycle. With diverse leaves, flower colors, flower shapes and seeds, aquatic plants can present many kinds of interest. According to life form they can be divided into:

Wetland plants - pampas grass, Miscanthus sacchariflorus, Japanese iris, variegated miscanthus, Pennisetum, etc.

Emergent plants - yellow flag iris, star grass, purple loosestrife, lotus, etc.

Floating-leaf plants - Euryale ferox, water lily, water poppy, Victoria amazonica, water poppy, Nymphoides peltata, etc.

Floating plants - Salvinia natans, water rice, Ottelia acuminata, water lettuce, etc.

Submerged plants - Hydrilla verticillata, Vallisneria, Potamogeton crispus, Potamogeton malaianus, etc.

Key points for garden maintenance of aquatic plants:

1. Adaptability to water depth

Apart from floating plants, the ecological factor with the greatest influence on aquatic plants is water depth, which directly affects their survival.

Wetland plants such as wild buckwheat, Miscanthus floridulus and pampas grass can only be planted above the normal water level.

There are many kinds of emergent plants, and their adaptability to water depth has a certain relationship with plant height. Taller plants have somewhat stronger adaptability to water depth; conversely, shorter ones have somewhat weaker adaptability. But generally speaking, water depth must not exceed 60 cm.

Floating-leaf plants are generally more adaptable to water depth than emergent plants. For example, water lilies are generally at 0.8 m, and Euryale ferox can also grow at a water depth of 1.5 m. Water chestnut is also a very interesting plant; as a floating-leaf plant its water-depth adaptability can reach 3 m, and when the plant grows to a certain size it can break off its roots and become a floating plant, no longer limited by water depth.

The water-depth adaptability of submerged plants is affected by light and water visibility. The better the water visibility and the stronger the light, the deeper submerged plants can be distributed. Generally the planting depth for submerged plants is twice the visibility.

2. Planting density

The design density of aquatic plants is discussed on the basis that after the aquatic plants recover they will fully cover the ground (water surface); the construction density is a planting density determined according to the plant's tillering and branching characteristics, the planting season, the fertility status of the planting soil, and factors such as the completion acceptance time. Construction density has practical value for saving construction costs.

3. Planting season

Aquatic plants are mostly herbaceous plants; during the growing season, especially in high-temperature seasons, new shoots sprout and grow very quickly, root activity is vigorous, and they recover very easily. Generally, after the roots of aquatic plants are injured, new roots can sprout in 1-2 days; after planting during the growing season, the plant form can generally recover effectively after 10-30 days.

Species with strong cold tolerance can be planted during the dormant period, such as water onion, Thalia dealbata, reed, water lily, Arundo donax, yellow flag iris, purple loosestrife, etc. The injured roots of these plants can withstand prolonged low temperatures and have physiological characteristics of resistance to low temperatures.

Species with poor cold tolerance must be planted during the growing season; planting such plants during the dormant period can very easily cause freezing damage. Such plants include pickerelweed, variegated water onion, papyrus, umbrella plant, Egyptian sedge, aquatic canna, etc. If these plants are planted during the growing season, the root-zone soil temperature is high, root activity is vigorous, and the plants recover quickly.

In low-temperature areas relative to the plants, they must be planted during the growing season. For example, papyrus, native to tropical Africa, and ginger lily, native to South China and Southwest China, can only be planted during the growing season in Hangzhou and areas farther north; otherwise they are prone to freezing damage and death.

4. Normal water level

A very important reason why many aquatic plants die over large areas after planting and fail to achieve the expected effect is the problem of water level control. It can be seen that the normal water level line is the lifeline of aquatic plants. In actual construction operations, sufficient attention must be given to the normal water level line. It is recommended that before setting out for planting construction, a level instrument be used on site to determine the normal water level line. When configuring plants, consider the water-depth adaptability of each plant as a hard indicator.

5. Wave impact

Small water systems generally have a small range and slow water flow, so they have little effect on the planting and growth of aquatic plants. For water bodies such as rivers and lakes, wind waves, boat wakes or rapid water scouring bring great difficulties to the planting and survival of aquatic plants. According to the wave characteristics, corresponding technical measures for wave dissipation and bank reinforcement should be adopted at planting time. For lake shorelines and riverbank lines with smaller lake surfaces and small waves, pine piles and bamboo piles can be used; they both dissipate waves and stabilize the bank, making them a better choice. Shoreline rockery treatment integrated with the landscape can also be used; the staggered rockery not only meets garden landscape needs but can also dissipate waves and stabilize the bank. After aquatic plants recover, emergent plants can play a certain role in wave dissipation, and their roots can also play a certain role in slope protection and bank stabilization.

Comprehensive advancement of ecological construction: problems in the application of wetland aquatic plants