Do Seeds Need Sunlight To Germinate? Here Are Some Answers

Seeds germinate in order to transform into seedlings, which eventually grow into larger plants.

Different seeds have different requirements when it comes to light for germinating. While most seeds can successfully germinate in darkness, some seeds need light to change into seedlings.

Light-dependent germination has especially been noted in small seeds, for instance, the lettuce seeds. While seeds that need light must not be buried in the soil at all or just lightly covered with some soil, seeds that germinate in the dark can be covered with plastic domes or a black plastic wrap in order to encourage the development of seedlings. However, it is trickier to understand the behavior of seeds that do need light, as the intensity and duration of light become a crucial factor in the growth and development of such seeds. A lot of research has been actually done to assess the right conditions for seeds to germinate. For those who are interested in gardening, sufficient exposure to light or darkness, along with proper humidity, temperature, and soil pH, are essential factors to know about.

With the right knowledge regarding seeds and how they germinate, you will be able to have your own beautiful garden in no time!

To learn more about why seeds need light, keep reading! You can also check out why do plants need sunlight and are seeds alive.

Do seeds need sunlight to germinate?

Germination refers to the process in which seeds give rise to seedlings that turn into fully grown plants. This is an essential procedure in the life cycle of plants. This process requires the perfect interplay of a number of events like the optimal temperature conditions, water, oxygen, and in some cases, sunlight to develop properly.

While most seedlings mandatorily require enough light exposure in order to grow healthily, not all seeds need light to germinate. For instance, the seeds of Allium and Phacelia prefer darkness for germination, and light may actually be a deterrent to the growth of these seeds. On the other hand, seeds of Lettuce, Poppies, Nicotiana, among others, need light in order to undergo the process of germination. So, for those wanting to start an outdoor or indoor garden, the light requirements of the seeds are mandatory to study!

You must be wondering, why exactly do seeds need light in order to successfully germinate? The answer to that is quite simple! Firstly, it is really quite interesting to note that in comparison to large seeds, smaller seeds are more light-dependent. Some research had suggested that this occurred due to a co-evolution of seed mass and light response, as a way to ensure that seeds of smaller size could successfully undergo germination only when they were close to the upper surface of the soil or barely covered. This is because smaller seeds do not have a lot of reserved food material. Hence, if they are buried too deep under the soil surface, the growing seedling would never make it out of the soil with the limited food reserve in place.

Apart from this, phytochrome, the photoreceptor present in plants, also help in mediating the response of plants to external light. Phytochrome has two forms, Pr and Pfr. While the former absorbs red UV light, the latter only absorbs far-red UV light. Pr is the inactive form of the photoreceptor, while Pfr is its active variant. At the soil surface, exposure to light allows the Pr to convert to Pfr, which results in germination. On the contrary, for small seeds like lettuce seeds, total darkness results in Pr not converting to the active form, and hence, germination is inhibited.

So, for tiny seeds that need light in order to transform into seedlings, it is advisable to simply press them into moist soil or add a thin layer of soil on top instead of burying them deep. Keeping the seed under a thin covering of soil would aid in enough exposure to direct sunlight, in addition to avoiding the establishment of dark conditions. Instead of soil, fine vermiculite can also be added to ensure the seeds germinate quickly. For instance, tiny carrot seeds, available in seed packets, can be kept on a seed tray, and a thin layer of soil or vermiculite can be added, keeping the tray exposed to direct light, for better germination.

Do radish seeds need sunlight to germinate?

Belonging to the family of Brassicaceae, Radish is quite a famous plant, as its root is used as a vegetable. Radish is grown all over the world and is popular among many gardeners due to the simplicity with which it can be grown. There are a lot of varieties of radish, depending on size, length, color, and shape. Additionally, based on season, radish is divided into spring or summer and winter varieties. Let us now deep dive to take a detailed look into the light requirements of radish seeds.

Radish seeds are usually not larger than 0.1 in (2.4 mm) in size. Hence, like most seeds of this size, radish seeds need light in order to germinate successfully. All in all, radish seeds require a minimum of six hours of full sun on a daily basis to achieve germination. However, being a plant used to cool conditions, Radish seeds can tolerate some shade, especially in areas with very high temperatures. In case you are planning on an indoor garden, artificial or fluorescent lights can also help these seeds to grow. The optimal temperature that radish seeds need to germinate is between 55-85 F (12.7-29.4 C).

Apart from light conditions, a number of other factors also affect the radish seed germination process. The ideal type of soil for radish seeds is the well-drained kind, having a pH between seven to eight. The moisture requirements of radish seeds are high as well, so it is best if the soil moisture level is checked from time to time in order to ensure the seeds germinate. Soils with high organic content and high humidity are also quite good for these seeds. Additionally, before sowing the seeds, they should be soaked in the water for some time. This leads to the thick seed coat softening up and faster germination. The seeds should not be sowed more than half an inch below the surface of the soil. Overcrowding is also an issue that leads to failed germination in radish seeds. So, for best results, a gap of 2 in (5 cm) should be maintained while planting the seeds.

Since radish seeds are quite fast-developing, after you plant seeds of this vegetable, the seedlings may appear as early as three to four days. However, in some situations, it may take as long as 10 days. These plants grow up to a length of 0.5-1.5 ft (15.2-45.7 cm).

While the nutritional aspects of radish are plenty, did you know that radish plays an essential role in various cultures, as well? For instance, in Oaxaca, a city in New Mexico, 'Night of the Radishes' is a part of their Christmas festivities. This event takes place on December 23, every year. On the other side of the world, in Korea and Japan, radish dolls are quite popular among children. Apart from all this, the oil extracted from wild radish variety is used as a source of biofuel. So, when you sow seeds of radish in your garden, remember all the significant facts related to this plant!

Do avocado seeds need sunlight to germinate?

In recent years, avocado has actually turned into one of the most popular fruits, quite commonly seen as breakfast food among celebrities and social media influencers. The avocado plant is part of the Lauraceae family and probably originated in south central Mexico. The avocado fruit bears a single seed, which is quite large in size, measuring nearly 2-2.5 in (5-6.3 cm) in length. Unlike some other seeds, planting an avocado seed is a tricky process. Generally, avocado seeds are hard to maintain, especially due to their specific needs and requirements. Avocado plants thrive best in warm climates, and their sunlight requirements vary throughout their life cycle. Continue reading to understand how much sunlight an avocado seed needs while germinating.

Avocado seeds need light to germinate. However, direct sunlight can cause considerable harm to the growth and development of the seeds. Hence, while sunlight is mandatory for germination to occur, it must be indirect or even reflected. Interestingly, avocado seeds can be germinated in both water and soil. In case of germinating in water, the seed should be kept in a glass of water, with only 1 in (2.5 cm) of the seed being submerged in the water. If this set-up is exposed to direct light, the intensity of the full sun would evaporate the water, which would lead to extreme dryness in the seed, and inhibit germination. So, keep this glass in areas with moderate light.

However, if you plan to use soil to make the seed germinate, then only half of the seed should be buried in the soil. The recommended planting depth is 1 in (2.5 cm). The end of the seed which remains exposed is too sensitive and would not be able to handle intense light. Hence, for avocado seeds that are germinating in soil, the entire set-up should be kept near a window that is south-facing. As a general rule, avocado seeds need a light of low intensity, so they should be germinated indoors. However, do remember that light is mandatory for this seed to germinate, so you absolutely cannot skip this process. In fact, a lack of exposure to light causes weak shoot and root development in this plant, along with slow germination, if at all it occurs.

Apart from the light requirement, many other factors help avocado seeds to germinate and successfully transition into seedlings. The soil in which you plant the seed of avocado should have good drainage and a pH of six. The soil should also remain free from any weeds or grass. Avocados can germinate in relatively cool temperatures. However, a temperature below 60 F (15.5 C) will prevent germination.

After successful germination occurs, the stem and roots are visible after a period of two to six weeks. If the seed were made to germinate in water, the formation of stem and roots would be instantly visible. However, in the case of soil, it would be a little longer, as the stem would need to sprout out of the soil. Once the stem has grown to a length of 6 in (15 cm), it must be cut back to 3 in (7.6 cm). This process helps in the growth of thicker and fuller stems. After the first cutting, the seed is finally ready for planting. Initially, plant the seed in an area in your outdoor garden with partial light. Over the next few weeks, gradually expose it to more and more direct light in order to harden the plant.

How much sunlight do flower seeds need to germinate?

Flowering seeds have varied requirements, especially in terms of exposure to light. Hence, if you want to sprout seeds of flowering plants, it is essential to go through this guide beforehand!

While some seeds require constant and direct light to germinate, many seeds of a variety of flowering plant species can manage to be under a thin layer of soil in order to germinate, as long as there is the presence of light. So, it is essential to differentiate between these two types before you start planting in your garden.

Snapdragon: One of the more common and most beautiful flowers belongs to the Snapdragon. It is one of the seeds that need full sun in order to germinate. Like many other seeds, seeds of this plant are available in seed packets quite easily in the market. Once you get the seeds, they should be gently pressed onto the soil instead of sowing them completely. This results in proper exposure to light. Since germination of snapdragon seeds is generally started indoors, grow lights can also be used. For best results and early appearance of seedlings, the seeds must be exposed to light for at least six hours every day. The seed will take between 7-14 days in order to germinate fully. After a period of eight weeks, the seedlings will be ready for planting outdoors in a garden.

Ageratum: The blue flowers of Ageratum are enough to lift anyone's mood. Belonging to the New World category of plants, Ageratum plants are quite easy to germinate and grow indoors. Like most seeds that require light, even Ageratum seeds should be left uncovered, as even a thin layer of soil can delay the process of germination. In case the sun is too harsh, it is best to keep the seeds in an area indoors that receives indirect sunlight. That way, the germinating seeds won't be damaged. These seeds need 7-10 days to germinate successfully, after which planting in an outdoor garden can be done.

Bachelor's Button: As quirky as the name sounds, the bachelor's button plays an important role in various folklores. For instance, the bachelor's button was usually worn by men who were in love. The fading of the flower meant their love had not been reciprocated. Unlike seeds that need constant and direct light, the bachelor's button plant seeds germinate when they are buried not that deep under a thin layer of soil. These seeds should be placed 0.25 in (0.6 cm) beneath the soil and covered very lightly to let some light shine through. It is also essential to keep the soil moist for best results. The seeds generally take one to two weeks to fully germinate.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for do seeds need sunlight to germinate? here are some answers then why not take a look at do cactus have seeds or are cucumber seeds bad for you?