Nursery Raising: The Key To Strong And Healthy Seedlings

Sowing healthy seeds or planting healthy seedlings is an important factor in achieving a healthy and productive crop. Seedlings are raised in nurseries for various crops, including vegetables, fruits and ornamental plants. Explore the benefits and challenges of raising seedlings in a nursery, as well as the best practices for seedling care and management in this article.  

Seedlings of crops propagated in nursery:

Seeds of certain crops are first raised in nursery under protected conditions to achieve maximum germination count and healthy plant establishment and then transplanted to main field. 

Most commonly grown crops in nursery:

• Vegetable crops: Tomato, Chilli, Brinjal, Onion, Cucurbits and Brassicas such as Broccoli, Cauliflower, and Cabbage.
• Fruit crops: Apple, Peach, Grapevines, Citrus (Oranges, Lemons, Lime), Strawberry, Kiwi.
• Ornamental crops: Roses, Marigold, Chrysanthemum, Lily, Gerbera, Tuberose.
• Field crops: Paddy, Sugarcane, Tobacco.
• Plantation crops: Coconut, Tea, Coffee, Rubber, Oil palm.

Why is Growing Seedlings in Nursery Important?

• Nursery provides better control over environmental factors such as temperature, light, and moisture, ensuring optimal growing conditions for seedlings.
• It allows farmers to monitor the plants more closely, making it easier to identify and treat any pest or disease problems that do arise.
• Seedlings grown in nurseries are generally healthier and more robust, making them more likely to survive the transplanting process and establish themselves in the field.
• They can be managed more efficiently in terms of water, fertilizers, and other inputs, which can reduce waste and costs.
• The seedlings tend to be more uniform in growth and development, leading to more consistent crop quality and easier management.
• Have less loss of expensive seeds due to proper germination.

Components and process involved in nursery raising system:

Choosing the right location for a nursery:

Nursery area should receive adequate sunlight to ensure proper growth. Choosing south-west aspect of placing nursery is preferable. Select nursery area having adequate drainage facilities to avoid water logging conditions. It should be selected near a water source and generally near shaded areas. In case of field nurseries, artificial shade can also be provided through shade nets if required. In addition, nursery areas should have sufficient organic matter content.  

Types of nurseries:

Nurseries can be raised in both fields as well as in protected structures like green houses and shade net houses.  

• Field Nursery: Nurseries in the field can be of two types – flat bed and raised bed nursery. Soil should be free from any weeds, clods and stubbles. In general, prepare raised beds of 1 – 1.2 m width, 15 cm height and of convenient length. Flat beds can be prepared in case of sandy soils which have good water draining capacity.
• Protected Nursery: Under protected structures such as poly house / green house and shade nets, poly bags and protrays are generally used for raising seedlings. The number of cells vary depending upon the tray. Usually trays with 98 cells are preferred. Size of the cell is important as it controls the amount of media used as well as water holding capacity. Polybags can also be used in greenhouse nurseries.

Selection of Growth Media:

The chemical and physical properties of the growing media are a key factor for successful nursery production. Optimum root growth is largely dependent on physical characteristics of media like moisture, aeration and nutrient holding capacity of the media. Sterile growing media must be used. Sand and compost are the most commonly used media. Coco peat, which is a byproduct of extraction of fiber from coconut husk a 100 % natural, biodegradable, spongiest and fibrous material is also normally used as main ingredient of nursery protray growing media. It has a high C: N ratio and high water holding capacity. It is a very good substrate for soil less cultivation in greenhouse vegetable nurseries. Other growth media includes peat moss, vermiculite, perlite and pumice.  

A mixture of growth media can also be used for healthy growth of seedlings. For instance, 1:1:1 ratio of red soil, sand and FYM mixture is used for growing watermelon seedlings. For additional benefits to growing seedlings mix biofertilizers like Trichoderma viride or Pseudomonas fluorescens  to media. Approximately 1.2 kg of cocopeat is required for filling one portray with 98 cells. 

Selection of Seeds or Vegetative propagules:

Select high quality seeds with germination percentage of at least 90%. It should also have high vigour. The selected seeds should be free from seed borne diseases. Also, select healthy and vigorous vegetative propagules (cuttings, grafts, layers) from the parent plant at the appropriate time of year, that are free from pests and diseases. Ensure that selecting seeds or propagules that are adapted to local growing conditions will increase the chances of success in the nursery. In order to prevent damping off, treat the seeds with Trichoderma viride at 6 ml/kg seeds or Carbendazim at 2 gm/kg seeds before sowing. 

Sowing and Germinating seeds in a nursery:

Prepare the nursery beds (field nursery) and fill the protrays / polybags (protected nursery) with the growth media. Sow 1 – 2 treated seeds per cell or per hole at 1 cm depth. Cover the seeds with the growth media. Adopt line sowing in nursery beds. Black polyethylene sheet or dry straw or grass can be used to cover the portrays or beds after sowing to conserve moisture and facilitate warmer temperature to initiate germination.  

Tools and Equipment needed for a nursery operation:

Hand tools such as shovels, rakes, hoes, trowels, and pruning shears are required for preparing the growing medium, planting, and pruning the seedlings. Rose cans are necessary for watering the seedlings. Use mini sprayer to spray pesticides in nursery.  

Management of young nursery seedlings:

1. Irrigation: Seedlings should be irrigated regularly with low pressure for better growth and development of the seedlings. Irrigating with Rose can, overhead irrigation, drip irrigation or sub-irrigation can be used to irrigate the seedlings. Overwateringis also dangerous for the growing seedlings as there might be chances of developing foliar diseases, collar and root diseases. Watering can be done in the morning. Proper drainage is essential to prevent waterlogging.
2. Nutrition: Nutrition for growing young seedlings is very much necessary apart from the nutrients present in the cocopeat or growing media. Supplying nutrition can be organic or inorganic. FYM can be incorporated while preparing the beds for sowing. Spray NPK 20:20:20 fertilizer once at 12th day after germination. One micronutrient mixture spray can be given 15 days before transplanting. Deficiency of any nutrients may lead to poor and stunted growth of plants and resulting in poor performance.
3. Pests and Disease management: Common pests in nursery include cutworms and sucking pests (aphids, leaf miners, scales, mites). Common diseases include collar rot, damping off, wilt. Drench the soil with Trichoderma viride at 10 gm/lit water or Mancozeb 75% WP at 3 – 4 gm/lit of water to control damping off, root rot, collar rot and other soil borne diseases. Regularly inspect the plants for signs of pest infestation and disease incidence. Follow field sanitation and remove the infected leaves and plants. Give a biweekly spray of neem oil at 1 – 2 ml/lit of water.

Hardening off seedlings before planting in the field:

Hardening is the process of gradually exposing grown seedlings to the normal climatic condition from protected condition to reduce stress and transplanting shock when seedlings are transplanted to the main field. Hardening may be done about 7 – 14 days before transplanting, by increasing light intensity slowly or exposing transplants/seedlings under full sunlight, reducing fertilizer application and watering.  

Transplanting the seedlings:

The right time of transplanting seedlings depends upon the crop.  

Transplanting time for few crops:

• Tomato: 25 – 28 DAS / 5 – 6 true leaf stage
• Chilli: 40 – 45 DAS
• Muskmelon: 20 – 30 DAS
• Onion: 42 – 48 DAS
• Brinjal: 30 – 35 DAS
• Marigold: 30 DAS
• Chrysanthemum: 30 – 40 DAS
• Cauliflower: 25 DAS

A thumb rule to decide the time of transplanting the seedlings or age of seedlings required for transplanting is the plant should at least spend 1/4th of it’s life cycle in the nursery. 

Common mistakes to avoid when raising seedlings in a nursery:

• Watering seedlings too often or too much can drown them or lead to fungal diseases. Only water when the topsoil is dry and use a well-draining soil mix.
• Similarly, neglecting to water seedlings enough can cause them to wilt and die.
• Avoid using irrigation water with high soluble salts as it will hamper seedling growth by salt accumulation.
• Seedlings have specific soil needs. Avoid using heavy, compacted soil or soil mixes that are too high in nutrients, as this can cause problems with root development.
• Planting seedlings too deep can inhibit root growth and lead to stunted growth. Make sure to plant seedlings at the right depth.
• Adopting wrong spacing can either reduce the number of seedlings or cause overcrowding.
• Poor ventilation can lead to fungal diseases and hinder seedling growth. Make sure to provide adequate air circulation and avoid overcrowding seedlings.
• Neglecting to harden off seedlings can cause stress leading to stunted growth or death.
• Failing to monitor pests and diseases can cause quick spread in a nursery and devastate young seedlings.