A sprouted seed is no longer a seed but a seedling, a miniature plant. The most important thing to consider and deliver is adequate plant light. Seedlings need more light than full grown plants, ideally as much as 16-18 hours a day. Additional light may be required for seeds started during the winter months.
Most seeds will not germinate without sunlight and will perform best with 12 to 16 hours each day. Indoors, place seed containers in a sunny, south-facing window and give the container a quarter turn each day to prevent the seedlings from overreaching toward the light and developing weak, elongated stems.
Once sprouted, most vegetable seedlings and other garden plants require at least 12 hours of good light per day, along with 8 hours of darkness. However, seedlings will grow the best when provided 14 to 16 hours of light.
The amount of light each seedling needs will vary from plant to plant. Those that require less light at an adult stage don't need as much as those that enjoy full sun throughout their life cycle. Seedlings exposed to too much light or heat will wither and die.
Your seedlings will need light, but they also need periods of rest (darkness) too. A good rule of thumb is to turn the grow lamps off when you go to sleep, and turn them on when you wake up (or use a timer). Read all about different types of grow lights here. Seedlings need blue night and red light.
Most of the seeds germinate best in dark environments. The presence of light tends to inhibit their growth. The light decomposes carbonic acid gas and expels oxygen which leads the seed to harden. These gases are key factors that promote germination.
Plant stems become “leggy,” meaning stems become long and thin and appear to be reaching toward the source of light. A lack of sufficient light causes the plant to grow long spaces on stems between the leaf nodes (the point where a leaf grows out from the stem).
This 100W LED light was just too close to the seedlings, causing them to get burned and turn purple and suffer, they can get burned just like we do in the bright sun! It is true that your seedlings need bright light to grow healthy and strong—but, too bright a LED light could actually damage them if it's too close!
Moisture, too little or too much, can be a real killer. Too dry a potting mix results in poor germination and uneven or stunted growth which stresses plants. The combination of too much moisture from overwatering and a warm atmosphere creates ideal conditions for fungal diseases.
Seeds need to be moderately moist to sprout. Seed germination is highly dependent on watering. Too dry and they won't get the message to sprout, too wet and they will rot in the dirt.
Seedling Daily Light Needs
Leave the grow lights on for 14 to 16 hours per day to provide light for the young seedlings. It's best to turn the light on early in the morning and turn it off around dusk.
Seedlings need 14-16 hours of light every single day, without fail. Don't leave them on for 24 hours a day though. Like us, they need to rest at night. So plan to keep your artificial lights on for 14-16 hours during the daytime, and turn them off overnight.
For many years, fluorescent shop lights were the go-to seed starting bulbs for gardeners, but LEDs have quickly replaced them as the standard choice. LEDs are usually more expensive than fluorescent bulbs, but they are very energy-efficient and long-lasting.
The Best Color Light for Seedling Growth
Initially blue light is important to help plants grow strong and sturdy. Seedlings need blue light in order to grow into hearty, robust plants.
Suffice it to say that it is mainly the light's effect upon a plant pigment called phytochrome within the seed. This relates to the type of light which the seed receives. As a generalisation, light in the red wave length usually promotes germination whereas blue light inhibits it.
Initially place seedlings outdoors in a sheltered spot – protected from wind and direct sun. Each day following, expose plants to another 30-60 minutes of filtered sunlight. Work your way up to giving plants direct morning sun, followed last by noon-day sun.
Until seeds have sprouted, keep the seed bed moist, never allowing it to dry out. Water with a fine-spray hose nozzle or watering can which will provide a fine misty spray and not wash away the soil. Water often enough (usually about once a day) so that the soil surface never dries out, but remains constantly moist.
With new grass seed, the aim is to keep the soil moist. Waterlogged soil will suffocate the new seeds. It is best to water the grass seedlings 2 to 3 times a day for about 5 to 10 minutes each time.
You want seedlings to be kept moist but not wet and never allowed to dry out completely. This most often translates to watering the soil for your seedlings at least once per day, if not more often. A spray bottle is a good way to water your seedlings and keep the soil moist without letting it get too wet.
A: In general, you should not leave grow lights on 24/7. Plants need a light-dark cycle to develop properly. It's believed that they truly do “rest” during periods of darkness, and probably use this time to move nutrients into their extremities while taking a break from growing.
For best overall results, BIOS recommends that you grow your seedlings under an 18/6 light cycle using Icarus LED lamps, set 24-36 inches from the leaf canopy, and under a blue light spectrum for their first 10-14 days. 18/6 simply means 18 hours of light and 6 hours of darkness.
All seedlings require sunlight. Seedlings will become leggy and fragile and will not produce to their potential if they do not have sufficient light. Table 1. Soil temperature conditions for vegetable crop germination.
Once those seeds sprout, proper seedling care is essential, and that includes supplying the growing plants with the right amount and quality of light. It is true that seedlings need lots of bright light to grow healthy and strong—but they also need a period of darkness in order to thrive.