Propagation is the most demanding stage of plant development. The growing conditions require precision and uniformity to produce consistent plants, leaving little margin for error. Whether you are engaging in seed propagation or growing from cuttings, a controlled environment, such as that found in a greenhouse, is ideal. Why? Unlike outdoor growing, in a greenhouse, you can ensure that the basic factors that affect plant propagation and overall growth, including temperature, water, nutrition, and light, are consistently optimized.

Greenhouse Seed Propagation: Temperature, Water, Nutrition, and Light 

When it comes to seed propagation, temperature and water management are the most important for root development, and then light and nutrition become critical. Seed germination greatly depends on the temperature of the root media, rather than the temperature of the air. Sub-optimal media temperatures can slow germination and interrupt growth.   

Optimal moisture and oxygen in the media are also necessary for germination. These rely both on the water delivery system and the quality of the water, itself. Keeping media too dry can result in poor growth and slow germination. 

While seeds come with their own nutrients, in the later stages of seed propagation, nutrition management is important for promoting seedling height and overall size. Lighting also takes on an essential role post-germination. While you may need to use curtains to control the natural light in your greenhouse during germination, the seedling stage requires uniform light across the canopy. That is where supplemental lighting comes in, especially during conditions of low natural light like in the winter months. 

Ensuring seedlings get the recommended amount of Photosynthetically Active Radiation (PAR) each day is essential. Daily Light Integral (DLI) measures the total amount of PAR delivered to your plants in a 24-hour period, and it is described in moles of photons per square meter (mol/m2). Even the sunniest regions may not be getting enough DLI at certain times of the year, so it would need to be supplemented. 

Supplemental lighting in the right intensity, over the right period, and in the right mix of wavebands, or colors, can influence seedlings and overall crop growth, from producing heartier roots to thicker stems to greater overall biomass, and more. In general, seedlings require a target minimum average DLI of 10-12 moles per day. When plants are ready for transplant and production, their DLI requirements will likely be greater, differing according to species. In fact, high-light plants, like tomatoes and peppers will require a much higher DLI of 22-30 moles per day to produce quality fruit for market. 

Greenhouse Cuttings Propagation: Temperature, Water, Nutrition, and Light 

As with seeds, managing the environment is essential for the propagation of cuttings. Providing the right media temperature will speed uprooting and proper moisture will prevent the plants from drying out. Good nutrition and sanitary practices are also key. In the early stages, low light levels should be maintained, and shading will likely be required on bright days. 

In general, cuttings require considerably less light throughout the day than mature plants. A target DLI of 5-10 moles per day is sufficient for consistent rooting and growth. Both the natural and supplemental lighting must be uniformly distributed over your plants since cuttings sitting in bright/hot spots will dry out faster. Such drying can also be mitigated by using LED grow lights for your supplemental lighting, rather than HPS since LEDs generate considerably less heat.  

Effortlessly Maintaining the Right Lighting Conditions 

Whether you are working with cuttings or seeds or finishing plants for market, it is important to maintain the precise DLI (duration) and light intensity (quantity) requirements of your plants. Light quality, or the spectrum delivered to your plants, is also critical to achieving your specific crop goals. 

Intelligent LEDs enable the light spectra to be tuned to your individual crop requirements, providing the ideal light at every stage of plant development. For example, red light can stimulate photosynthesis, green can drive photosynthesis deep within the canopy, blue can encourage compact growth, while far-red can promote flowering. 

Intelligent LEDs and lighting controls technology such as helioCORE™ can help you set your lighting strategies according to production stage as well as crop type. Multiple lights can be grouped to create light zones with standardized schedules and settings, which can be saved in custom libraries for your staff to use. At the same time, helioCOREcan monitor your energy consumption and utilize low-cost hours to decrease operating costs in your smart greenhouse. 

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