Do seeds need sunlight to start growing?

Author: Eulah Greenholt PhD  |  Last update: Wednesday, November 29, 2023

Light is not necessary for a seed to germinate, no. The majority of seeds grow most effectively in the dark. Light, which is essential for seedling growth, may actually hinder the germination process. The three primary and necessary conditions for a seed to germinate are water, oxygen, and temperature.

Do seeds germinate in dark or light?

Not all seeds have the same light requirements. Most seeds germinate best under dark conditions and might even be inhibited by light (e.g., Phacelia and Allium spp.). However, some species (e.g., Begonia, Primula, Coleus) need light to germinate (Miles and Brown 2007).

At what point do seedlings need sunlight?

Days 1 – 3: Place your seedlings outdoors in a shady spot that will only get 3-5 hours of direct sunlight throughout the day. Days 4 – 5: Place your seedlings in a slightly sunnier spot that will get about 5-6 hours of direct sunlight. Days 6 – 7: Place your seedlings in a full sun spot (6+ hours of direct sunlight).

Do seeds need light or just heat?

The only seeds that will germinate faster with light are the ones mentioned above in this article (or other seeds that require sunlight to germinate). Most seeds do not need grow lights until after they germinate. Most seeds germinate faster if they are warm.

Can seeds start in shade?

Some plants can be sown outside direct into a shady spot. An area shaded by deciduous trees or hedging, which won't be in full shade until May or June, is ideal for crops that don't need much warmth to germinate, such as chard and beetroot.

Do seeds need light to germinate?

Can seedlings grow in darkness?

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.

What seeds don't need sunlight?

Seeds That Will Germinate With or Without Exposure to Light
  • Alyssum.
  • Aster.
  • Balsam.
  • Cole Crops.
  • Celosia.
  • Cosmos.
  • Cucumbers.
  • Dianthus.

Will seeds germinate under LED light?

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.

What kills seeds?

Pre-Emergent Herbicide: Prevents seeds from germinating or kills germinating seeds before seedlings emerge from soil; must be applied before weed seeds germinate. A common example of a pre-emergent herbicide is a Crabgrass preventer, which prevents Crabgrass seeds from establishing new plants.

How many hours of sunlight do seeds need to germinate?

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.

What is the best way to start seeds?

How to Start Seeds Indoors in 4 Easy Steps
  1. Fill a large bowl with seed-starting mix and mix in a little water to evenly moisten the soil. ...
  2. Place your seed tray inside the drip tray and fill each cell to just below the top with soil.
  3. Sow your seeds. ...
  4. Cover the tray and place it under your lights on the heat mat.

Why do seeds grow faster in the dark?

The light slows stem elongation through hormones that are sent down the stem from the tip of the stem. In the darkness, the hormones do not slow stem elongation. The seeds in the dark-grown condition rely upon the stored chemical energy within their cells (lipids, proteins, carbohydrates) to power their growth.

Should seeds be kept in the dark?

For the same reason you don't store your bag of potatoes in a well lit place, you should not store your seeds in one. Light is another important cue to the seed that it is time to sprout. When storing your seeds in see-through glass and plastic containers, it is important to put these containers in a dark, dry place.

How do you know when a seed is germinating?

While the speed of germination varies slightly across varieties, seeds should absorb moisture within two days and produce a root and the first leaf within four days. At this point, the seed is considered to have germinated.

What is the most difficult seed to germinate?

Some seeds like Allium 'Purple Sensation' and Eryngium giganteum need a long period of cold-moist stratification with alternating temperatures. These are the most difficult seeds to germinate.

How often do you water seeds to germinate?

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.

Is it better to soak seeds before planting?

Soaking can accelerate germination and increase the proportion of seeds that successfully germinate. Seeds have evolved a protective coating around the embryo so the embryo can survive being dispersed by some means. The coating protects the seeds until they find themselves in a suitable place to grow into a new plant.

Do seeds need light to germinate indoors?

Some seeds don't need light to break through their seed casings and sprout. Most seeds germinate best with controlled amounts of UV generation, but there are seeds that germinate in the absence of light.

What is the best light for seed germination?

For the average home gardener starting seedlings indoors, a fluorescent or LED lamp will usually be the best choice to ensure that your plants get the quality, intensity, and duration of light they need to stay in peak condition.

What type of light is needed for starting seeds?

Fluorescent or LED Lights

For most home gardeners, a plug-in shop fluorescent or LED light fixture is the perfect type of light to use for seed starting.

What seeds like darkness to germinate?

Some other popular types which prefer darkness for germination are:
  • Calendula.
  • Centaurea.
  • Delphinium.
  • Gazania.
  • Nemesia.
  • Primula sinensis.
  • Schizanthus.

Will seeds germinate on top of soil?

Will grass seed germinate on top of the soil? Yes; in fact, germination will suffer if too much soil is placed on top of the seeds. The experts at Jonathan Green recommend placing a thin layer of mulch or topsoil over them to help keep them moist and warm and promote growth.

Why is light necessary for seed germination?

Small seeded plants that form soil seed banks for instance, are expected to germinate only in the presence of light, as a mechanism to avoid germinating too deep in the soil where they would deplete seed nutrients before reaching light for photosynthesis (Pons 2000).

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