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How To Choose Seedling Trays For Nursery

The intensive seedling raising technology of vegetables mainly adopts the light substrate as the seedling carrier and the seedling trays as the main container. Seedling raising is the key technical link of vegetable production. According to the production needs, different vegetable varieties, seedling raising seasons and cultivation modes shall select nursery trays with different hole sizes. In order to improve the yield per unit area, the seedling trays with more holes should be selected as far as possible without affecting the seedling quality.

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1.What is seedling trays?

Seedling trays, also known as cell tray, has become an important instrument in industrialized seedling production technology. Whether flowers or vegetables, seedling trays is the most fundamental reform of modern horticulture, which provides a guarantee for fast and mass production.

1.1 Seedling trays making material

With the development of plastic manufacturing industry, the seedling tray price is gradually reduced and its application is more and more widely. The materials for making seed trays are polystyrene foam, polystyrene, polyvinyl chloride and polypropylene. Manufacturing methods include blow molding and injection molding. The vegetable seedling trays is mostly made of polystyrene(PS), which has the characteristics of anti embrittlement, aging resistance and not easy to deform.

seed germination tray

1.2 Types of seedling trays

The standard seed trays size of is 540mm × 280mm. The holes diameters of seedling trays are different, and the number of holes is between 6-800. Generally, 50 cell~288 cell seed trays are used for vegetable seedling raising. For the cultivation of medium and small seedlings, it is appropriate to use 72 cell~288 cell plug tray.

The hole shape of seedling trays mainly includes round and square. The inner side of the round hole is smooth, and there is no right angle around, which is conducive to the rooting and packing of plant roots, and is more suitable for the growth of small seedling crops. For example, 6 cell seed trays, 12 cell seed trays, 18 cell seed trays, 24 cell seed trays, 32 cell plug tray51 cell plug traysseedling tray 104 holes.

The four corners of the square hole are also changed from the initial right angle to a rounded corner. The matrix contained is generally about 30% more than that of the circular hole. The water distribution is relatively uniform, and the seedling root system is more fully developed. The square hole nursery trays is mostly used for the seedling raising of large seedling age vegetables. For example, 21 cell seed trays32 cell seed tray40 cell seed trays, seedling tray 128 holes162 cell seed starting trays.

plant starter trays

1.3 Are seedling trays reusable?

Most of the common seed cell trays in the market are 0.6 ~ 1.2mm thick. The commercial seedling trays with the thickness of 0.6~0.8mm have low price and poor hardness. They are mostly used for manual sowing and disposable use. Best seed trays thickness is 1.0~1.2mm, and the hardness of the seedling cell trays is good. It is suitable for machine or sowing line operation. It can be reused after disinfection.

1.4 Color of seedling trays

The seedling trays color is generally black and white. We all know that black absorbs light and white reflects light, and the color of seed tray will affect the temperature of plant roots. The white planting trays has good reflectivity, and it is used for early seedling raising in summer and autumn, so as to reflect light and reduce heat accumulation at seedling roots. The black seedling trays was selected in winter and spring because of its good light absorption, which was beneficial to the green root system of small seedlings.

1.5 Advantages of vegetable seedling trays:

Vegetable plant trays for seedling raising can be completed by machinery in the process of filling, sowing and germination. The operation is simple and fast, convenient for centralized management, storage and transportation, and is suitable for large-scale production. Less seed consumption, uniform sowing and high seedling rate, which reduces the cost of seeds.

The seedlings in each hole of the plastic seed trays are relatively independent, which can not only reduce the transmission of diseases and pests among each other, but also reduce the competition for nutrition among seedlings, and the root system can be fully developed. The greenhouse seedling trays increases the seedling density, facilitates intensive management, improves the utilization rate of greenhouse and reduces the production cost.

propagation tray

Due to the agriculture nursery trays unified sowing and management, the growth and development of seedlings are consistent, the emergence is neat, and the quality of seedlings is improved. Using seed trays raising and transplanting are simple and convenient, do not damage the root system, have high survival rate and short slow seedling period.

2.Types of vegetables using seedling trays

Most vegetables suitable for reusable seed trays cultivation and transplanting are eggplant, melon, cabbage. In recent years, with the increase of labor cost and the development of facility planting and planting mechanization, the number of eco friendly seed trays cultivation and transplanting of other vegetable species is increasing year by year, mainly celery, lettuce, onion and non heading Chinese cabbage. Cheap seedling trays cultivation and transplanting is becoming a main production and cultivation mode.

The seedling raising of fruit vegetables (mainly eggplant fruits and melons) can be roughly divided into winter, spring and summer, autumn according to the sowing season. The seedling raising in winter and spring generally requires that the seedling age is long, the seedling is large, and can be harvested as soon as possible after planting; Seedling raising in summer and autumn requires relatively small seedling age seedlings with high root activity, which is conducive to slow seedling after planting.

Which seedling trays is best for vegetables?

In spring, 105 cell seedling trays restricted the root development of tomato and cucumber, reduced the photosynthetic electron transfer rate of leaves, and reduced the biomass and strong seedling index of vegetables. 50 cell seed trays and 72 cell plug trays had almost no significant effect. Considering the economic cost and production efficiency, it can be used as the appropriate hole size for seedling raising.

best seed starter trays


Because the seedling age of eggplant is long and most of them are grafted, most of them are cultivated with 50 cell plug trays and 72 cell seed trays. In order to enhance the cold resistance of Eggplant in autumn and winter, grafting seedling raising technology is mostly used. 

The research shows that for the eggplant hole disc seedling sown on August 18, the precocity of 32 cell plug tray is 5 days earlier than that of 50 cell propagation trays, and the total yield increases by 15.3%; If Eggplant Cultivation is not grafted after autumn, the seedling age is 30~35 days, 4~5 leaves are planted, and the agriculture nursery trays with 50 cell plug flats and 72 cell propagation tray is suitable.


For the winter and spring stubble seedling of pepper, the number holes of plastic planting trays can be selected according to the needs of the grower for the size of the seedling. Generally, for the colonization of pepper with more than 6 true leaves, 72 cell seedling trays can be selected, and 105 cell seed trays or more holes can be selected below 6 true leaves. In summer and autumn, 128 cell plug trays are generally selected for pepper seedling raising, and the seedling age should be controlled within 25~30 days with 5~6 leaves. 


The temperature of tomato seedling cultivation in summer and autumn is high, the seedling age is short, the physiological seedling age reaches 3 leaves and 1 heart, the calendar seedling age is about 35 days, and the seedling can be planted when it is about 15cm long. 72 cell trays are preferred for the tomato seedling tray. The physiological seedling age is 6~7 leaves, and 32 cell seed tray and 50 cell seed trays is mostly used.

seedling tray manufacturers


105 cell plug trays is suitable for cabbage seedling raising in summer and autumn. In the middle of August, Chinese cabbage was planted in the open air. At this time, the high temperature and too much rain often affect and inhibit the growth of Chinese cabbage seedlings, resulting in reduced production in the later stage. The 50 cell plug trays is generally used for seedling raising, and the seedling age is about 30 days.

The large seedling planting in the middle of September can prolong the growth period of Chinese cabbage. After planting, the high incidence period of soft rot of Chinese cabbage is missed and the yield is improved, Reduce bacterial invasion.

other varieties of vegetables:

In addition to fruit vegetables, there are many other varieties of vegetables planted by seedling transplanting mode, such as cabbage, celery, lettuce, onion, etc. compared with fruit vegetables, the seedling trays of these vegetable varieties are relatively small, and the seed trays specifications should be adjusted accordingly.

72 cell plug flats or 105 cell plug flats is more conducive to the root development of cauliflower in summer and autumn. Celery seedlings are generally raised with 128~200 cell seed trays, with calendar seedling age of 50~80 days and physiological seedling age of 4~6 leaves; The planting density of heading lettuce is generally 63000~67500 plants/hm2, and 345~375 trays/hm2(200 cell plug trays) or 570~600 trays/hm2(128 cell trays) are required.

3.Factors affecting seedling trays selection

3.1 Seedling raising method

The common seedling raising methods of vegetables mainly include hole tray seedling raising, floating seedling raising, tidal seedling raising and so on. Different seedling raising methods also have different hole selection of commercial seed trays.

Tray seedling raising is the most common seedling raising method. Light matrix is used as seedling carrier and professional seed trays is used as container. The floating seedlings of vegetables are mainly used for vegetable production such as pepper and leafy vegetables. Containers can use best seed starting trays or foam plug trays.

Tidal seedling raising is a technology gradually applied to vegetable seedling raising in recent years. Due to the water saving and energy saving of tidal seedling raising technology, and can effectively solve the "umbrella effect" of large seedlings, it has been applied in some modern seedling farms. However, due to the relatively high cost, the application area is small.

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3.2 Mechanical transplanting

In recent years, with the increase of labor cost, more and more growers choose mechanical transplanting for vegetable production, which puts forward higher requirements for seed plug trays. The integrity of seedling root lump is the first test of whether seedlings can be transplanted mechanically. The factors affecting the integrity of seedling root and lump include vegetable varieties, seedling age, cultivation measures and so on.

In order to better meet the needs of existing transplanting machinery, it is recommended to select 72~128 holes for vegetable seedling raising, and the plant height of seedling trays is 12~18cm. 

There are too many holes, the root lump of hole plate seedlings is small, the stability is not enough during mechanical transplantation, and the seedlings are not easy to stand upright in the planting hole, resulting in the inactivity of transplanting and planting, or the need for additional manual seedling support.

 There are too few holes, resulting in too large seedlings, or less root system, incomplete root lumps, easy to scatter lumps, which is not conducive to mechanical grasping and easy to damage seedlings.

4.How to store the seedling trays?

Because of the convenience of management and small floor area, more and more people use the seedling trays, but many people don't care about storage. Generally, they are stacked together after use, placed in the corner of the greenhouse or exposed to the sun. In this way, the service life of the nursery seed trays will become shorter and cause waste.

seed starting flats

The production materials of plastic seed starter trays are different, the characteristics are naturally different, and the preservation methods are different. Polystyrene seed trays: it has good toughness, strong aging resistance, non-toxic and so on. So just stack them together and keep them in a dark place.

PVC seedling tray: due to its hardness and brittleness, it ages quickly under direct sunlight, and is easy to break from the edge of the tray during use. Therefore, when storing this kind of nursery seedling trays, it should be placed in a dark and humid place. They can be directly stacked together and buried in wet soil. They can also be stacked together, covered with wet old grass, and placed where the sun cannot be directly exposed.

5.Precautions for reuse of seedling trays

If the reusable seedling tray is to be reused, the used starting trays must be selected and those aging and damaged plug must be removed. Then thoroughly clean and disinfect the professional seed starting trays that you want to reuse, especially the cheap black seed trays that may have chloramphenicol residue.

It is recommended not to use bleach for greenhouse seed trays disinfection because some greenhouse planting trays can absorb chlorine in bleach and react with polystyrene to form toxic compounds. It will seriously affect the germination and growth of next season crops, especially Begonia, which is more sensitive.

seed sowing trays

After thoroughly cleaning the used nursery planting trays, it shall be disinfected in a surface disinfectant such as quaternary ammonium salt such as "Green Shield". The relatively simple method is to soak and disinfect with contact bactericides such as tobuzin and carbendazim. Remember, seedling flats must be thoroughly washed and dried before use. If the density of the foam tray is very high and it does not melt at high temperature, steam disinfection can be used to sterilize it.

For the thin seed planting trays, the number of times of reuse should not exceed times. Because long-time moving will cause the seed growing trays to break, and the seedling separator and seedling transplanter will also produce mechanical wear on the seed raising tray. Over time, the drainage hole becomes larger, and the cultivation medium will leak out from the bottom hole of the plant seedling tray.

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