Methods for disinfecting flower growing soil and the causes of low seed germination rates and their solutions

Many people may have encountered this situation: after sowing flower and nursery stock seeds, half or more may have already died by the time they emerge, and the germination rate is too low. What is the reason? Improving the germination rate of flower and nursery stock seeds is a highly technical task. To improve the germination rate of flower and nursery stock seeds, you should first understand the reasons affecting the germination rate so that they can be handled reasonably. Here, we have gathered some information online on this common phenomenon to summarize the causes of low germination rates in flower and nursery stock seeds and the solutions.

Seed problems

There are currently many flower seeds on the market, and some packaging is very elaborate. When purchasing, whether domestic seeds or imported seeds, please pay attention to the production date and shelf life marked on the packaging bag. Do not buy seeds without a marked production date and shelf life. This is because expired seeds have mostly lost their vitality and will not germinate or emerge. In addition, when purchasing seeds, flower growers should have a basic understanding of them, for example, they should know whether the seeds they buy are annual or biennial flowers or perennial flowers, and whether they are spring flowers or autumn flowers. According to general common sense, seeds sown in spring generally bloom in summer and autumn; seeds sown in autumn generally bloom in spring and summer (excluding woody flowers). If this is reversed, it is very difficult to achieve the expected flowering purpose without certain cultivation equipment. Purchased seeds, especially flower varieties that have never been cultivated before, should be given heightened attention.

Seeds not properly treated

Seeds of different flowers should be treated with different seed treatment methods: for seeds that germinate easily, soaking can be used. For example, scarlet sage seeds can be soaked in 40°C warm water for one day and one night, rinsed clean, and then sown. For hard seeds such as asparagus fern, tree peony, orange jasmine, crape myrtle, and winter daphne, it is best to first soak them in 40°C warm water for about 48 hours, then sow them in pot soil. After 20 to 30 days, they can sprout and grow. For seeds with a short dormancy period that germinate easily, such as pearl bush and redbud, soaking in 40°C to 60°C warm water for 24 to 48 hours allows direct sowing.

Some flowers, such as lilac, wintersweet, and some herbaceous flowers sown in autumn, require a certain period of low-temperature treatment (0°C to 10°C) to promote after-ripening, break embryo dormancy, and germinate. The specific method is to mix the seeds with sand at 60% humidity, then put them into a plastic bag, tie the bag tightly, place it in a flower pot, and bury the pot in open ground 40 to 60 cm deep; the seeds can also be placed in a 3°C to 5°C refrigerator for 60 to 90 days, then taken out and sown in spring. Autumn sowing can also be chosen so that the seeds pass through natural winter freezing outdoors and germinate and emerge in spring of the following year.

Some flowers, such as fringetree and Chinese peony, have seeds with dual dormancy of radicle and hypocotyl, meaning their radicles need to pass through a high-temperature stage of 25°C to 32°C for 1 to 2 months or longer before dormancy can be broken. For these seeds, they must be mixed with wet sand before sowing, go through a period of high temperature, then shift to low temperature, and after high-temperature treatment, spring sowing will allow rapid germination and emergence.

Failure to pay attention to the temperature during seed germination

In addition to certain moisture conditions, the germination of dry seeds must also have a certain suitable temperature. For example, the suitable germination temperature for sweet alyssum in the Brassicaceae must be 5°C to 20°C, the suitable germination temperature for Gerbera jamesonii must be 20°C to 25°C, and the suitable germination temperature for primrose must be within the range of 15°C to 18°C. If the temperature is too high or too low, it will affect the flower germination rate, especially causing seed mildew and rot, greatly reducing the seed germination rate and seedling survival rate.

Sowing time not properly grasped

Seeds with small particles and loose, thin seed coats, such as those of chrysanthemum, asparagus fern, garden balsam, crape myrtle, and Chinese trumpet creeper, are suitable for late spring sowing; seeds with large particles, firm seed coats, or oily content, such as those of Chinese rose, pomegranate, kumquat, and southern magnolia, are suitable for autumn sowing. Seeds with small particles, thinner seed coats, and high-temperature requirements should be sown promptly after maturity; for example, cyclamen and cineraria should both be sown in early summer. Flowers such as China pink and pansy should be sown in late autumn.

Improper sowing methods for flower seeds

Flower sowing is divided into open-field sowing and pot sowing, and sowing methods include broadcast sowing, row sowing, and hole sowing. No matter which method is used, the soil is required to be loose and airy, fine in particles, hygienic and non-toxic, rich in humus nutrients, and moderate in pH, which is beneficial to seed emergence. Before sowing, water thoroughly; after sowing, cover with plastic film or cover the flower pot with a glass sheet to help preserve moisture and prevent the soil from becoming too dry, which would affect seed germination and emergence. The sowing depth should be about 2.5 times the diameter of the flower seed grains. For fine seeds, such as those of cockscomb, August chrysanthemum, wax begonia, and cineraria, fine sand or soil powder should be mixed evenly and scattered over the seeds. After sowing, during seed germination, attention should be paid to spraying water to maintain moisture, but spraying water should not be excessive, to prevent lowering soil temperature or rotting seeds and seedling fibrous roots, which is unfavorable for improving the germination rate.

Ignoring the influence of light

After flower seeds are sown, light can increase soil temperature and induce seed germination, and it is especially important for seeds to break through the seed coat, produce roots, and expose sprouts. It not only affects the seed germination rate, but is also directly related to whether good and strong seedlings can be grown. Therefore, from sowing to transplanting, it should be a process from darkness to weak light and then to natural light, and according to the different stages of sowing, germination, and emergence, the light needs of flower growth should be met as much as possible.