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Common Mistakes Made While Growing Seeds Indoors

Guidance on Watering, Lighting, and Other Growing Factors

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The Spruce / K. Dave

It is quite economical to start seeds indoors, especially when the seedlings grow into robust plants. However, growing seeds indoors can be challenging. To significantly increase your chances of success, avoid these common seed-starting mistakes.

Watch Now: Mistakes to Avoid When Growing Seeds Indoors

Not Supplying Enough Light

Seedlings need a lot of light to grow into sturdy, healthy plants. No matter what anyone tells you, chances are that you do not have enough natural light in your home to grow robust seedlings. Even a south-facing window usually will not do. You can, however, use artificial light to achieve the right amount of light required by seedlings. To do so, obtain grow lights explicitly designed for plants. Or, for a more economical solution, purchase large fluorescent shop lights outfitted with one warm bulb and one cool bulb.

Suspend the lights from chains so that you can raise the lights higher as the seedlings grow. Keep the lights as close to the seedlings as possible without touching them (2 to 3 inches). When seedlings first appear, keep the lights turned on for 12 to 16 hours per day. To reduce your hands-on time, use a timer to turn the lights on and off automatically.

Applying Too Much or Too Little Water

The amount of water you supply can make or break seedling growth. Watering is one of the most challenging aspects of seed starting. Because seedlings are so delicate, there is very little room for error when it comes to watering. You must keep the sterile seed-starting medium damp but not wet.

To increase your chances of getting it right, here are a few things you can do:

  • Create a mini-greenhouse to keep soil moist: cover the container with plastic until the seeds germinate.
  • Water from the bottom to enable the seedlings to soak up water through the container drainage holes. There is less chance of over-watering when you use this approach. Add water slowly for 10 to 30 minutes, and use your finger to touch the top of the soil to ensure that moisture has reached the top of the container.
  • Check soil moisture at least once a day.
  • Buy a self-watering, seed-starting system.

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The Spruce / K. Dave

Starting Seeds Too Soon

Many plants do not tolerate cold temperatures, and exposing them to chilly air or cold soil will stress them out. Chas Gill, who runs the Kennebec Flower Farm, agrees that one of the biggest mistakes people make when starting seeds is starting the seeds too early. Stressed-out plants are more susceptible to pests and disease. Most plants are ready to go outside four to six weeks after you start the seeds.

Planting Seeds Too Deeply

Seeds are finicky when it comes to how deep they are planted. Some seeds need complete darkness to germinate and others require light to germinate.   Proper planting depth is usually provided on the seed packet. If there is no information on the packet, the rule of thumb is to plant seeds two to three times as deep as they are wide. Determining depth can be a challenge, but if you are not sure, err on the shallow side.

For seeds that need light to germinate, make sure the seeds are in contact with the seed starting medium but are not covered. To do this, gently press the soil medium to create a firm surface. Then, place the seed on top of the medium and gently press down, making sure the seed is still exposed.

Moving Seedlings Outdoors Too Soon

There is no benefit to a tough-love approach with seedlings when they are young. They will either instantly die or become weak and then fail to thrive. Even the most stalwart plants, when young, need a considerable amount of coddling and attention.

When your seedlings are large enough to plant outdoors, you need to prepare them for the transition by hardening off.   Hardening off gradually prepares them for outdoor conditions like wind, rain, and sun. The hardening-off process is simple, though it can be time-consuming; it involves exposing your plants to the elements gradually. The first day of hardening off, place your seedlings outdoors for one hour, and then bring them back indoors. Gradually increase the amount of outdoor time every day for 6 to 10 days. You will need to make some judgment calls based on the outdoor temperature and the fragility of your seedlings. If it is a particularly cool day or very rainy, you will want to decrease the time of that hardening-off session.

Sowing Too Many Seeds

When sowing seeds, begin modestly if you are a beginner. If you sow more seeds than you can reasonably maintain, it will become challenging to nurture the seedlings into adulthood. Depending on the type of plant you want to grow, you might be able to direct-sow seeds in outdoor containers or in the ground when outdoor temperatures warm up.

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The Spruce / K. Dave

Keeping Seeds Too Cool

For seeds to germinate, most must be kept warm: about 65 to 75 degrees Fahrenheit. A favorite place to keep seeds warm in order to germinate is on top of the refrigerator. Or, you can purchase seed-warming mats to place under the seed trays. Once a seedling emerges, they can tolerate fluctuating temperatures (within reason). Whatever type of light you use, natural or artificial, make sure it produces enough heat to keep the plants in the 65- to 75-degree range.

Failing to Label Seeds

To be able to identify seedlings as they grow and to know when they will be ready for transplanting, you should label the seed containers as you are sowing. For every type of seed sown, use popsicle sticks or plastic plant markers and permanent ink pens to record the plant name and date sown. Insert the plant labels into the soil near the edge of the container or tray.

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The Spruce / K. Dave

Giving Up Too Soon

Starting seeds can be a difficult process. However, one of the most satisfying benefits of this labor of love is eating a tomato or marveling at the flowers that you nurtured from day one. Growing plants from seed takes dedication, attention, and time. Recognize that you might make mistakes along the way, but you should not give up. The results outweigh the challenges along the way.

Growing seeds indoors isn't hard, yet keeping them alive can be challenging. You can save a lot of money by starting plants from seeds.

Cannabis Light Schedules: Vegetative Stage vs Flowering Stage

Cannabis plants keep getting bigger and bigger with long days, and start making buds when you give them long nights.

Cannabis is a “photoperiod” plant, which means the amount of light received each day decides when the plant starts flowering or making buds. This article explains how much light a day your photoperiod cannabis plants need to grow and start budding, so you get to a happy harvest day. What about auto-flowering strains?

Vegetative – Seedling or clone leads to Vegetative Stage –
Give 18-24 hours of light a day

Flowering – Flowering (Budding) Stage leads to Harvest –
Give 12 hours light & 12 hours dark each day

Seedling or Clone

While not technically a “stage,” all grows start with cannabis seeds or clones.

Indoors

Plant your seeds or clones when you’re ready to start growing! What are clones? https://www.growweedeasy.com/cloning

Outdoors

Some outdoor growers start their plants indoors to give them a headstart before putting plants outside.

If you’re growing cannabis outdoors with seeds, you should wait until a few weeks after the spring equinox to put your seeds outside. In the northern hemisphere this means seeds go outside in-or-after April, In the southern hemisphere seeds go outside in-or-after October.

For growers starting with cannabis clones, generally you should wait a few weeks longer than with seeds. Cannabis clones are more prone to flowering early outdoors than seeds, so you might want to put your clones out in late Spring or early Summer. (What are clones?)

If you live in a cold climate, you must also wait until after the last frost before putting your plants outside. Freezing temps will kill cannabis plants. Strain choice is very important. Some strains flower earlier than others. For outdoor growers in cold climates, it’s important to make sure you grow a strain that is matched up with your local weather, so that plants are ready for harvest before temperatures drop.

Vegetative Stage

The vegetative stage is one of the most important parts of the life of your cannabis plant.

The vegetative stage is the growing stage of the plant. When in veg, cannabis plants grow bigger and taller, growing only stems and leaves. As a grower, you are able to control the size and shape of your plants in the vegetative stage using simple training methods.

During the entire vegetative stage the plant does not produce buds at all. It only grows stems and leaves. During the vegetative stage plants tend to grow very fast, especially when conditions are right.

What keeps cannabis in the vegetative stage?

Short nights keep cannabis plants in the vegetative stage. You can keep a cannabis plant in the vegetative stage for basically forever as long as the plant continues to get short nights (shorter than 1s-12 hours, depending on the strain).

Cannabis will stay in the vegetative stage as long as the plant gets short nights (less than 11-12 hours of darkness each day)

Whether you’re growing indoors or outdoors, you must make sure your cannabis plants get at least 13 hours of light each day to stay in the vegetative stage. If your plant gets a few long nights, it may start budding before you want.

The plant can receive as much as 24 hours of light a day while in the vegetative stage. Many indoor growers provide 18-24 hours of light a day (known as 18-6 or 24-0 light schedules) during the vegetative stage to encourage faster vegetative growth.

Don’t want to worry about light schedules? For growers that don’t want to pay attention to light schedules, there are auto-flowering strains of cannabis, which will automatically go through their whole life in about 3 months no matter what light schedule is provided. For some growers, an auto-flowering strain may be more simple than a traditional (photoperiod) strain.

Indoors

Most indoor growers provide 18-24 hours of light a day (known as 18-6 or 24-0 light schedules). Giving your cannabis plants more hours of light each day in the flowering stage will encourage faster growth.

Lingo: When a grower provides 18 hours of light a day and 6 hours of darkness, this is commonly known as the 18/6 light schedule. For 24 hours a day, this is referred to as the 24-0 light schedule.

Outdoors

As long as your plant is getting plenty of light a day, your plant will automatically stay in the vegetative stage from late spring until late summer. Every strain is a bit different.

Flowering Stage

Cannabis starts budding when plants get at least 12 hours of uninterrupted darkness each night. After plants start budding, they must continue to get long dark nights until harvest or they may revert back to the vegetative stage.

Indoors

Indoors most growers put their plants on a 12-12 schedule to initiate flowering. Outdoors the plant will naturally start budding in late summer when nights are growing longer and longer as winter approaches. Just make sure plants aren’t exposed to light during their dark period!

What is 12-12 Lighting?

The indoor grower will need to artificially induce flowering/budding in plants by changing the light schedule so the plant receives only 12 hours of light a day, and 12 hours of uninterrupted darkness.

Once the plant is changed over to the flowering (12/12) light schedule, there is generally another 6 weeks-5 months (average 2.5 months) before the plant’s buds are ready for harvest.

Outdoors

Outdoor growers wait until their cannabis plants start naturally flowering on their own, usually after mid-summer when days start getting shorter than 12 hours.

It’s important to make sure plants aren’t exposed to light at night during their dark period, even street lights or spotlights, as this can prevent cannabis plants from flowering properly.

Growing Indoors? Not Sure When To Switch To Flowering?

So indoor growers have a choice to flower their plants whenever they want… When is the best t ime to start flowering your cannabis indoors?

The real answer is that it’s a matter of personal preference and also depends on what end result you’re looking for. There are two major considerations when choosing the right time to switch to 12/12, the age of the plant and the height of the plant:

Age: Some growers feel that a marijuana plant which has been grown from seed will not produce as many buds or have enough resin production if the plant is not given at least 60 days in the vegetative stage to mature before it’s changed over to the flowering stage. This is not true. many growers initiate flowering soon after germinating a seed in order to keep plants small and short. This is often called “12-12 from seed.” Just remember, no matter what you do, a young cannabis plant will not start flowering until it is 2-3 weeks old. Even if you put a seed on a 12-12 schedule from the beginning, it will not start properly budding for about 3 weeks. When growing with cannabis clones, age is not an issue and growers can switch directly to flowering once your clone has established roots. This is because even though a clone may be small, it’s still a ‘mature’ plant since it is made of a piece from a mature plant. Rooted clones tend to grow much faster for the first few weeks than plants grown from seed. In any case, age is not much of an issue, and you should switch your light schedule at the time that best fits your needs.

Height: A general rule is that your marijuana plant will double or triple in size during the flowering stage from the point where you first change over the light schedule to 12/12. Some plants will grow more, some will grow less, but a good rule of thumb is to change your light schedule over to flowering when your plants have reached half of their final desired height. Bending, known as “LST” or “low stress training” can be used to control colas that get too tall. Simply bend too-tall colas down and away from the center of the plant. Some growers will even slightly break or “supercrop” branches to get them to bend at a 90 degree angle. For those growing in a small space, height may be the primary concern. However, there are many techniques available to grow a short, bushy weed plant or basically train your cannabis plant to grow into any shape you want.

Here’s an example of LST to keep a plant short:

In optimal conditions if height and space is not an issue, you would probably want to vegetate your cannabis plant for 60 days or more before switching it over to flowering. This gives your plant plenty of time to grow big (so you get bigger yields), and allows new growers to dial in their grow before plants enter the sensitive flowering stage. In the vegetative stage, it is easy to recover from problems, but problems are a lot more serious in the flowering stage, where mistakes can dramatically hurt your final yields.

Giving cannabis plants more time in the vegetative stage, and taking time to train them to fit your space, will give you the best final yields. However, if space is tight, then it’s better to switch when the plant is half the final desired height, or even to just attempt to flower your cannabis plant straight from seed.

Harvest!

After the vegetative and flowering stage are over, it is time to harvest your plants!

What do I need to know about light cycles and flowering my marijuana plants? Plants keep getting bigger and bigger with long days, and start making buds when you give them long nights.