If you’ve recently purchased some flower or vegetable seeds, you may be curious about how to get them to germinate. After all, we all know that plants need light to survive. Photosynthesis is a basic scientific concept taught in most schools, so how many inches deep should you be planting your seeds?
Do seeds germinate better in the dark? Yes! At least, some will germinate under darker conditions better than lighter ones. In fact, some seeds may be stunted by too much lighting. Planting depth is an important consideration if you want your seeds to thrive.
Different seed packets will suggest different things, as no two seeds are the same. You wouldn’t plant flower seeds the same way you would plant carrot seeds. Since light requirements vary, there isn’t one set rule of thumb to follow, and you will have to adapt to each seed’s needs.
There is some debate among gardeners over the benefits of shallow versus deeper planting, so keep reading if you want to find out which seeds you may be planting in dark conditions, and which prefer light conditions. We’ll also find out what else it takes for a seed to germinate.
Germination, the process of turning a viable seed into a hardy seedlings, is an important factor for even the master gardener. Different environmental conditions can influence whether your plant seeds make the cut, or end up never sprouting at all.
Soil moisture is another essential aspect of germination. Keeping your soil moist is necessary no matter the seed you are using. Crop seeds, a herb seed, organic seeds and nonorganic seeds, all of them will need at least some moisture.
Be careful not to overwater however, as this can practically drown your seeds. Too much water can do drastic damage depending on the seed. For example, the outer seed coat of a pea seed will wrinkle up like skin after a long soak in a bath tub or a pool, while quinoa seeds will just rot from over exposure to moisture.
The process of germination directly impacts the life span of your seedling, plant, flower, or crop. An increase or decrease of as little as one percent in seed moisture can cut the lifespan in half. Seeds can be very fussy indeed, at any stage of the germination process. Try using different hose or watering can heads to water seeds to different volumes.
Temperature conditions are another key factor, as optimal germination temperature can be difficult to achieve. Equipment such as greenhouses can help raise temperature conditions for more tropical climate plants, but lowering them can be a pain.
Consider using germination mats to help moderate the temperature conditions of your seeds. These mats can be used as cooling mats, or heating pads, allowing experienced gardeners to better monitor the process of germination. If you’re using a container of a flat of seedlings, then covering them in plastic wrap with an air hole can also raise the heat.
Seeds also need a particular amount of air, so be wary of your planting depth. If the soil surface is too far from your surface, then keeping the soil moist won’t suffice. Plants are living things, and they can suffocate if not properly cared for, as they need oxygen to produce carbon dioxide.
The CO2 is a byproduct of the plant producing energy. You may want to consider only lightly packing the soil on top of your seed, allowing small breaks when you cover with soil. A light soil cover will allow some air through, while maintaining proximity to the moist soil to get your seedling adequately watered.
Contact with soil can also allow some light in. As previously stated, light requirements can vary with seeds, but they are the most common outlier for germination. A thin layer of soil can pass through air, but also a limited amount of sunlight, so consider not packing down your organic soil so tightly.
Speaking of organic soil, this can be a great way to encourage your seeds to thrive. Like farmers working on field soil, quality nutrients and support reaching your seeds can lead to a longer life span, and a higher yield if you’re growing vegetables. Moist soil with support can really boost your germination success.
Sunlight vs Artificial Light
So what do you do if your seed does end up needing light? Obviously planting outside with sunlight is probably your first option, but if you’re looking to grow and germinate indoors then artificial light can be an option for you to employ. Although, there are noticable differences between sunlight and artificial lights.
While some seeds prefer an absence of light, some will need direct light. Sunlight produces specific wavelengths which are optimal for plants, these being the wavelengths for colour. The very same things that give a rainbow its colours. LED lights may not be able to fully replicate these waves.
Direct light from the sun can influence different plants, as some need different colours. Take for example jungle trees, which commonly reflect far red light. This extreme end of the colour can be achieved with a far red UV light, but only some tropical plants will need them.
Other fluorescent lights can produce far red light, suitable for woodland plants with specialised phtyochromes (receptors for light). Some colour waves can actually burn and harm plants, so make sure you research your plants prior to turning on your grow lights.
The presence of light may also need to be monitored. In the natural environment, the sun isn’t up for 24 hours at a time. As such, your plants may only need or wants a few hours of light at any given time. Check how much light per day you are giving your seed to germinate, if required at all.
Handling the issue of light should be a constant task, especially once your seed has germinated. Your plants will need to photosynthesis to turn light into energy, but most plants also need light to root. These are the very basics of seed sprouting, so no matter how dark your seed likes, make sure you have light ready the moment you see some leafy greens.
Seeds Which Need Light
Light can be one of the most basic requirements for seed sprouting and germination. Although it is the factor with the most variation of the main four (the other three being oxygen, moisture, and temperature), it can still play a pivotal role on an entire seedling tray.
So which commercial seeds need light to germinate? Let’s take a look at both vegetable and flower seeds, so you can get busy gardening again. Since seeds are very particular in their conditions for germination, even a master gardener should pay close attention to this list:
- Cucumber seed
- Eggplant seed
- Broccoli seed
- Tomato seeds
- Bean seeds
- Cactus seeds
- Palm seed
- Carrot seed
- Nicotiana seeds
You may also find a common middleground for some viable seeds. Cucumbers are notoriously easy to grow, although if you want to encourage healthy germination then light is suggested. Eggplant seeds are also less fussy, not necessarily needing light to thrive but light helping out if needed.
Seeds Better for the Dark
There is some allowance for seed treated better in the dark, but these seeds are usually structured differently than their light needing counter parts. A thicker seed casing can prevent light from reaching the main portions of the seed, preventing germination in direct sunlight.
Seed casing is the most common sign of a seed better suited to darker conditions, but it’s not the only one. Below, we’ll take a look at some of the more common flower and crop seeds you might be using, and whether they’re suited more to less light:
- Lettuce seed
- Fat bean seeds
- Coriander seeds
- Chinese cabbage seeds
- Calendula seeds
- Gazania seeds
- Allium seeds
Even the most high quality organic seed might haver darker requirements. For example, organic seed potatoes prefer a more dim environment, and plenty of moisture. Once you get a good germination crop going for crop plants, you’ll be likely to find annual seedlings with minimal effort as time goes on with future planting cycles.
When has a Seed Germinated?
Germination is typically indicated by the protrusion of a stem and leaf growing from the seed. Keep an eye out for some happy round leaved seedling ssprouting from your soil or tray, as they can be the first signs that you’ve turned a stale seed into a common seedling.
Some plants perform epigeal germination. Epigeous germination is when the seed germinates above the soil, and you can identify this by the seed casing. If the seed casing is above the soil surface, then don’t stress! This just means your plant has taken a unique turn on the germination process.
You may also spy differences between monocot seeds and dicots. Monocots contain a single seed leaf inside, while dicots contain two as their name might suggest. Again, if you see some plants germinating with more leaves, then this shouldn’t be alarming for you.
Seeds vs Seedlings
Depending on the germination rates of your seeds, you may find a varying amount of seedlings. A seedling is when the stem and seed leaf begin to protrude from the seed, and the plant starts to fully become active and alive. Seeing this beautiful process is just one of many benefits of gardening.
Getting the seedling is the difficult part. Proper oxygen flow and oxygen uptake, cool conditions and moist conditions, metabolic conditions with light where needed, ideal time of planting, all these will factor in to what the seed considers to be optimal conditions.
All manner of things may go wrong, so if you’re having difficulty try adjusting these conditions. Cool the greenhouse through ventilation, reducing the risk of leaf burn for plants with leaves. Ensure you have enough container and greenhouse space for your planting stock, so things aren’t too crowded.
Signs of Non-Germination
Seed dormancy can prevent full germination. This sleep period, named seed dormancy, is a natural occurance for most plants. It is a defense mechanism, to sprout at different times to avoid outside factors like sudden bad weather or the presence of herbivorious animals from killing an entire yield of plants.
If your seeds fail to germinate, then it could be a sign of seed dormancy. However, if none of your seeds produce then consider the conditions they are in. Crowded seedlings are less likely to sprout, for example. A dormant seed springs to life unexpectedly, so keep an eye on those plants.
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