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How to Germinate Seeds
Germinating seeds indoors is a great and easy way to grow your own food and flowers. You can do as much or little as your time, energy, resources, and desire allow. The seedlings can stay indoors and grow into mature plants, or you can nurture them until they are big enough to be transplanted outdoors. It does not take very much space to start hundreds of plants and all you need to start are a few basic supplies.
Starting your own seeds can save you money too. Depending on what you grow, it can more than pay for itself in the first year in many cases. The benefits don’t stop there though. Growing your own seedlings allows you to increase your garden output when you start them early enough indoors; you can gain up to two additional months of growth or more when you start seedlings indoors versus waiting for soil temperature to warm up enough to sow them outdoors. This is especially beneficial in areas that have shorter growing seasons, and you want to grow crops that require a longer time to mature. It also gives you greater variety than what you find in the store as you can grow whatever variety of plants you want, when you want, so long as they are hardy enough for your growing region or you have the supplies to grow them indoors.
Starting seeds indoors also allows for greater survival rates for your seedlings. Indoor cultivation does not subject young seedlings to extreme hot or cold weather fluctuation as well as other weather that they might not withstand. It also shields them from pest and animal browsing. Not all crops are suitable for indoor germinating though. Crops like beans, beets, carrots, corn, lettuce, peas, spinach, turnips, and some cucurbits like zucchini do better directly seeded outdoors.
All of the preparation and well-intentioned reasons for germinating your own seeds will not matter much if you are starting with bad seed. “Bad” seed could be rotten, sterile, pest or disease ridden or just plain too old to be viable. Seed purchased from any reputable retailer as well as any Certified seed should be perfectly safe and ready to grow for you. The percentage of seed purity and germination is required to be printed somewhere on a seed’s packaging in most, if not all regions of North America and Europe.
Depending on the type of crop you are growing, seeds can be obtained anywhere from a hardware store, garden center, big box store, general retailer, mail order catalogs, thousands of online vendors or if the crop you are growing is cannabis, then a specialty retailer that sells only cannabis or hemp seeds. Pricing on seeds varies wildly based on numerous factors. Besides just straight up quantity, there is quality, lineage, whether or not the seed is organic, open-pollinated, heirloom, or genetically modified, prices will vary greatly.
Depending on the type of crop you are growing, seeds can be obtained anywhere from a hardware store, garden center, big box store, general retailer, mail order catalogs, thousand of online vendors or if the crop you are growing is cannabis, then a specialty retailer that sells only cannabis or hemp seeds. Pricing on seeds varies wildly based on numerous factors. Besides just straight up quantity, there is quality, lineage, whether or not the seed is organic, open-pollinated, heirloom, or genetically modified, prices will vary greatly.
Instructions on how to sow, when to sow, and where to sow are often also included somewhere on a seed packet. Generally speaking, the more expensive the seed, the more information is included with it. This is not always true, but for instance a national brand of seeds will likely have brighter, more professional packaging with more information than a locally procured, seed saving group’s packaging. Anymore, however the cultural requirements for just about every commercially available type of seed can be found online for easy reference.
Preparing to Seed
Preparing a clean, well-lit, and accessible area for germination is essential. IF you have a greenhouse space or grow room, then that part is easy. If you are trying to repurpose other space in your home or business, then there are several preliminary steps you need to take to increase your odds of successful germination and healthy seedlings.
A good growing area for germinating seeds is one where you control the temperature, humidity, lighting, and water. This space should not be in a heavily “trafficked” area where people or animals might knock your trays off the bench. It should be a forgiving space where you can spill soil or water and be roomy enough for your seedlings to grow. Some people can achieve this setup in their basement, others can do so in their kitchen. It does not matter where it is so long as you can control the variables.
A “rookie” mistake is to put the germinating seeds on a windowsill. While it may seem ideal because light comes in there, it is not in fact the best place for your seedlings, and it will not do any favors to your windowsill either. Temperature fluctuates widely by a window. These areas tend to be the hottest during the day and the coldest at night. Seeds need a more constant temperature. Seedlings grown on windowsills also tend to get tall and “leggy”. Natural light is also inconsistent and artificial grow lighting is far more reliable.
Having all of your trays and containers ready before seeding and accessible at the time of seeding will help to make the sowing process easier and more efficient. Seeds can be somewhat forgiving as to what they are germinated in so long as it is a clean, well-drained growing environment that allows access to light, and has room for them to develop a root system. The containers or trays may be made of plastic, compressed peat moss or coir, wood fiber, or other recycled or re-used materials. If you are only growing a few plants, you can seed directly into individual pots not more than about 2 inches (5 cm) wide or deep. If growing several plants, it may be most economical to sow them into a shallow tray in rows. You may have to go back and thin them out some if enough space is not allowed between each seed, but more than one type of plant can be seeded into the same tray. Regardless of the tray or container type, it needs to have adequate drainage holes.
Containers and trays for seeding can certainly be reused. If they have been used however, it is critical to thoroughly clean and sterilize them before using them again. This will help to avoid and cross-contamination of any pathogen that may have affected the last crop, even if you did not ever see evidence of anything being wrong with the prior crop’s health. Better safe than sorry, as with most things. There are numerous commercially available cleaning and sanitation solutions that containers and trays can be dipped into or sprayed with. You can also make your own solution with one part bleach to nine parts water. Make sure to wear all appropriate protective equipment when handling bleach or any other disinfectant.
For seed germination, it is necessary to invest in some grow lighting. This can be anything from relatively inexpensive fluorescent lighting to more advanced LED lighting. Other higher intensity grow lights should be reserved for more mature stages of growth. Either way you will not want to rely solely on natural light, even if growing in a greenhouse.
Seedlings will need both cool (short wavelength) and warm (long wavelength) light to properly develop and photosynthesize. If using fluorescents, you can mix cool and warm tube bulbs, such as those on standard shop light ballasts. They will not however give as full a rage of lighting as LEDs. Fluorescents have been evolving though. Newer T5 types or T8 types are more efficient than the older T12 types. They give more light and use less energy in doing so. All are available in warm and cool; some are even specifically designed and marketed as grow lighting.
LEDs are fast becoming the go-to lighting for seed starting as well as plant development. The technology keeps improving every year and their costs keep going down. They cost more upfront than fluorescents but the savings in energy will make up for it over time. You will likely get more vigorous and faster growing seedlings under LED lights than fluorescents. The type of crop, your purpose in growing (hobby versus commercial growing), and your budget will dictate which type you start with. The volume of LED lighting on the market aimed at growers can be overwhelming. Costs vary widely and in general, like anything else, you get what you pay for. The higher priced LED lighting will generally provide more intense lighting with a better wavelength balance than inexpensive LEDs.
Regardless of type of grow light, you will also need some type of frame to suspend them to. Ideally it will be one that is adjustable. There are hundreds of commercially available grow light frames out there, some available as all-in-one kits. You can also build your own using PVC or any other material too.
Seeds do best to germinate in sterile media, with a pH between 6.0 and 6.5. They prefer a soilless media of finely-textured amendments such as a blend of peat moss, perlite, and vermiculite. They may also contain some amounts of composted materials, coconut coir, and lime. Make sure that you have plenty of this seed-starting media on hand before your start seeding. There are hundreds to thousands of available commercial blends that will serve you fine, or you can always mix up your own blend. Avoid using soil from your field or garden though. It is usually too heavy, dries out too quickly, and often contains weed seed or other unwanted pathogens which are fine outside, but can negatively affect an inside grow tremendously.
It is necessary and good practice whenever seeding or even transplanting to pre-moisten your media before starting. Soilless mixes in particular are hydrophobic; they naturally repel water until they are fully saturated. Seeding directly into dry media, will generally cause your seeds to dry out. The dry media should be put into a clean bucket, tub, or wheelbarrow. Then, keep adding clean water to it, stopping to mix it up occasionally until it is thoroughly moistened. Upon grabbing a handful of the media, squeeze it into a ball shape. If water wrings out of it, the moist is too wet. It the media crumbles in your hand, it is too dry. If it somewhat retains the ball shape, it is probably just about right for seeding.
Once you have properly moistened media, fill the containers or trays that you are going to be seeding in no sooner than the day before seeding, and preferably within a few hours of seeding. You can even do it right before seeding, but do not wait too long and have the media dry out or else you will need to go through and re-moisten it. Each container or tray should be filled up to within an inch or so (2.5 cm) from the top of the container. Pat the soil down lightly, making sure to include the edges and corners. Do not tamp down or compact the media too hard, just enough to get a more or less even surface. You are now ready to start seeding once all other preparations have been made.
Sowing the Seeds
Finally, after all of the prep work, it is time to seed. The actual time it takes to seed is often much less than the time to prepare for seeding and certainly less than the aftercare commitments, but properly sowing is as important as any other step for a successful crop. Follow the seeding instructions on each packet if there are any. Some seeds require special steps before seeding such as to soak in water or to crack or score the seed coat with a knife. Cannabis seeds germinate better if they are soaked in room temperature water for 12 hours before sowing. After soaking for 12 hours, if it sinks, it is likely a viable seed; if it floats after being touched, it will not likely germinate. If there are no such directions, or special handling requirements on your seed packet, then you can generally assume that there are not special requirements for your seed beyond putting it in soil or media and making sure that it gets water.
Some seeds do better to be just barely covered while others need to be plunged down further into the media. If unsure about proper planting depth, there are two time-tested methods: sow each seed three to four times deeper than the seed is wide or sow the seed deep enough that you could get three more seeds on top of it. If you plant it too deeply, it may not germinate. It is best to give a little space between each seed. In the absence of clear spacing instructions, keep at leach one inch between seeds so that you do not have to go back through and do any thinning as they start to germinate and so each seedling has room to develop its own roots. For larger crops like melons or squash, some growers will cluster seeds and then thin out the weaker ones, only allowing for the strongest to grow.
Sowing into soil or other media is not the only way to get your seeds to germinate. Some growers will actually start them in cotton balls or a moistened paper towel. To use this method, put the seed(s) into a dry paper towel of cotton ball. Then, spray them with water until moist, but not dripping. Then place the moistened paper towel or cotton ball containing the seed(s) into a plastic container or between disposable plates or bowls. Whatever is used make sure that it stays dark, warm, and humid at all times during germination. Every few hours they will need to be sprayed with more water. It the paper or cotton dries out, then it is likely that the seed, especially if it already started to germinate, will die. Keep everything moist for several days until the germination is complete, the seed has developed a root or roots, and then transplant into a container to continue developing. Some growers prefer this method as they then only are caring for only those seed that germinated and not wasting soil or media on those that might not have. Whichever method is used to sow and germinate, make sure that you do not break your streak there. Continue on with the aftercare they need to ensure healthy plants and a bountiful harvest.
When to sow seeds will depend on the crop and where you are growing them. If you are intending to grow indoors and relying on artificial lighting, then you can seed anytime. If you are planning to transplant your seedlings outside once they are mature enough then you will need to calculate your seeding time based on how many days or weeks they take to germinate and when there is no more threat of freezing temperature in your region. Many states and provinces have resources available online with this information. It is worth noting that a common mistake that many eager growers make, is to start the seeds too early. This can result in plants that are too tall and spindly if they are looking for light, plants that will not hold enough water because their containers are full of roots that have pushed out all of the media and plants that will not be acclimated well once put out. Make sure to align your sowing dates with the amount of time each unique variety of plants needs to germinate and mature, along with your individual climatic region and temperature range.
Care of Seedlings
Your careful planning and thorough preparations will also pay off here as you manage the light, water, heat, and nutrients requirements of your crop. Once your seeds are safely nestled into their new home, they are poised to start germinating. You can make the process easier and more successful for you and them. Make sure that all of your seedling containers are properly labeled. Permanent marker works best as light, and water will quickly fade ink or pencil writing on your labels. It is also a good idea to have timers set up for both your irrigation and lighting.
Depending on the type of seeds you have sown, they may or may not need light right at the outset. Some do not need it until they have started to emerge above the soil. Cannabis seeds for instance do not necessarily need light until they have poked up through the soil layer. Seeds that need darkness to sprout can be covered in layers of newspaper or paper towel, or in dark plastic bags until they have emerged. Seed packaging will dictate what your particular plant needs for initial light, but all seedlings need light once they have germinated and are above the soil line and it is best supplied either totally with artificial lighting or at least with supplemental grow lighting.
As mentioned above, there are many options for grow lighting. Fluorescent tubes work well for beginning growers often. Figure one 4-foot tube for every two trays of seedlings. LEDs are more also user friendly but are more costly. Whichever way you decide to go, mounting them so that you can raise them up as your plants grow will help your plants grow larger, faster. Keeping the light source two to four inches above your growing seedlings will keep their growth more vigorous and even. The amount of light your plants receive is subject to the inverse-square rule; every time you double the distance between your plant canopy and the light source, the plants are receiving only one-quarter of the light they were receiving before, so the closer to the light, the better.
How long you keep the lights on will also depend on the type of crop that you are growing and how much light your plants can absorb each day. It also depends on the intensity of the lighting. Most plants need 12 to 16 hours of light each day (they do need a dark period to develop properly).
Seed germination requires water. Once the process of germination has begun, it must have a continuous supply of it, or the seedling will dry out and die. It is important to keep your media moist during germination and development, but to avoid supplying too much water also. It is a delicate balance to be sure.
A lot of inexperienced growers make the mistake of overwatering their seedlings in an effort to make sure that they don’t dry out. Too much water is arguably worse than not enough water. Seedlings of all kinds are prone to a disease called “damping-off”. It is a fungal disease that can develop in the same conditions that your seedlings want to develop in: warm, and moist soils. Infected seedlings will quickly wither, fall over, and die. Too much water in the root zone will also cause your seedling’s roots to rot if air cannot circulate within the media.
To avoid damping off and to lessen the chance of overwatering in general, it is important that the soil or soilless media used is well draining. The surface of the soil should be allowed to dry out a bit in between waterings. One approach to help avoid damping off is to bottom water. This is a method of irrigation that requires growing containers to have holes on the bottom so that they can absorb and draw up moisture from the bottom of the pot. The top of the soil can then be moistened with a spray bottle, allowing it to slightly dry in between waterings without the entire media drying out completely.
The importance of the proper growing environment for your seedlings cannot be understated. This includes temperature, humidity, and air flow. Some of these aspects can be controlled cheaply and easily, others will require some mechanization. Air flow can be helped by properly spacing your trays or containers. You want air to be able to circulate around each plant. A fan or fans will also help with this. They will also help to regulate the temperature by moving around either warm or cool air.
At the outset, a good humidity range to try and attain is 60 to 70 percent. Humidity can be cheaply and easily controlled somewhat by using clear, plastic domes over your trays and containers. They work like a tiny greenhouse. They allow light in, but keep heat and moisture in. It is important to ventilate them sometimes if they get too hot and they will need to be removed completely once the seedlings grow tall enough to touch the roof of the dome. Clear plastic sheeting can also be used. As the seedlings grow, the plastic can be tented up over the plants with stakes. This will also increase the soil temperature as well. If growing on any large scale, it is advisable to invest in humidification and/or dehumidification equipment depending on your particular region and growing environment.
A good, average temperature range for germinating seeds is about 65 to 75°F (18 to 24°C). This is what the soil temperature should be, not necessarily the surrounding air. The air temperature should be in the 55 to 70°F (13 to 21°C) degree range (Providing heat at the root zone can be achieved with a heating mat. Temperatures within the containers or trays can be as much as 5 degrees F different that the air around them. Seeds germinate sooner, with healthier root systems when given a warm environment. Bottom heat can also prevent the disease damping off which kills a lot of young seedlings. These heating mats can be plugged into a timer to be used during the colder parts of the day. It is not suggested however, to plug both grow lights and heating mats into the same timer as the needs for both do not always align perfectly. It is also not advisable (or safe) to use other devises as heat mats. Electric blankets and heating pads are not designed to get wet like heating mats designed for germinating seeds.
The supplemental heat will only be needed during germination and can be removed once the seedlings have their first set of true leaves. You can heat the air immediately surrounding your seedlings with a foil blanket if it is difficult or cost prohibitive to heat the entire space. If you are only germinating a tray or two of plants, the top of a refrigerator can provide some additional warmth or near a stove or furnace as well. For larger areas, a supplemental heater is recommended.
Your germinated seedlings will not need much for nutrients at first. They feed off of nutrients stored within them that were transferred from their respective mother plants. Applying a fertilizer too soon can actually damage and burn your plant. Wait until your seedling has several sets of true leaves before applying any feed. Even then, do not apply any fertilizer at full strength. Apply a weak solution (1/4 to 1/3 the recommended rate) of a general-purpose fertilizer until your seedling is ready to be transplanted into its next stage, whether that is a container or outside into the field.
Transplanting into containers
Once your seedlings have grown past the cotyledon leaf stage and have developed at least their first full set of true leaves, and preferably their second set, they can be transplanted. It is not critical to transplant them at this stage, but it is important to do so before they have outgrown the cell or area where they were sown. If you are not ready to transplant just yet then at least make sure that your seedlings have been thinned so that each has at least a one-inch (2.5 cm) radius of soil or media all around the stem. At this early stage it is critical to let the roots grow as vigorously as possible, so make sure they have plenty of room to do so. This could be by directly transplanting them outside or into another container to be grown inside or outside.
When transplanting into another container, make sure that you do not put them into a container that is either too big or too small. The tendency can be to put them into pots or containers much too large for them thinking that they will grow into it, but it is better for your plants if you transplant them multiple times. Often, young seedlings that are placed into containers that are too large for them tend to get overwatered since there is so much media in the larger pot as compared to the size of the plant’s roots. It is better to keep “up-sizing” your seedlings as they grow than to put them into a container that is too large. Conversely, if it is too small, you will stifle its growth and potentially cause the plant roots to push out all of the media in its surroundings, making it difficult to give them enough water. Until they are ready for their last transplant, or to be planted outside, put them in a container size appropriate for a few weeks of growth and then keep transplanting them into gradually larger sized containers as appropriate.
There are numerous types of appropriate containers for seedlings. They can go into fabricated plastic packs and trays, fiber or peat pots, fabric pots, or even plastic cups that have drain holes poked into the bottom of them. As long as the seedlings have room to grow and excess moisture can drain out, then they should be reasonably happy. When you are ready to make that first as well as subsequent transplants, a careful hand is needed to protect the young plants.
Seedlings should be handled delicately when transplanting. Using a spoon or a plant tag to gently scoop up the entire root mass with each plant is vital to its survival. When handling the plant itself after it has been excised from the soil, do so gently by holding an upper leaf. Grabbing it at the base by the stem can cause harm and the growing point can be damaged. It is better to risk tearing off a leaf, which can be replaced, that to break the stem which cannot.
Once the transplant is complete and the seedlings are in their new home, you can give them a light feeding of a nutrient solution. Generally, a quarter to half the recommended strength on the fertilizer’s packaging is safe for its first feeding in its new home. The water should be applied gently as well until the seedlings have rooted in. Give them their nutrients and irrigation through a shower head attachment or a watering can, to avoid a full stream that could dislodge the recently transplanted seedling and potentially damage it.
Transplanting into the field
If you are starting seeds indoors to transplant outdoors, the seedlings will need to undergo a period of “hardening off” to give them a better chance for thriving. Plant that germinated indoors and developed without exposure to full sun, winds, or temperature fluctuations may not be instantly acclimated to their new outdoor home. If a hardening off period is not observed, then your seedlings may get scorched leaves at a minimum; they may even wilt and die. The hardening off procedure is not difficult and will take about two weeks.
Once outdoor temperatures are consistently above 45°F (7°C), start taking your seedlings outside during the warmest part of the day but put them in a shady location away from wind. This could be under a tree canopy, porch, or any other protective structure or environment. Bring them back inside before the temperatures start to cool off in the evening. Every day, they can be exposed to longer periods of time and gradually moved into a sunny location. After about two weeks of this, you can safely leave the seedlings outside unless there is still a risk of freezing temperatures. Another way to harden plants off is to use a cold frame.
Cold frames are simple unheated structures that act as mini-greenhouses. They are commercially available or can be constructed from a wide range of material so long as light can get in and they can be opened to ventilate and so that the plants in them can be watered. To harden off plants put out in a cold frame, the door or vent should be opened a little bit more on each successive day. After about two weeks of this, they should be ready for transplant into the garden or field, but again, not if freezing temperatures are still possible.
A third way to harden your seedlings off is to plant them outside where you want them to grow and protect them with a row cover. This is a light, translucent cloth that will provide some protection from the direct sun, wind, pests, and cold. Each day, the row cover can be left off for a slightly longer period of time until the threat of frost has passed.
Regardless of which method if used to harden your seedlings off, it is important to help your plants to get rooted into their new home. If your seedlings were started in a peat pot, fiber pot, or any other type of biodegradable container, the bottom should be carefully cut off, or holes should be put into it so that the roots can grow out of it and latch onto the soil. If the collar of the pot sticks up above the soil line it should be cut off lest it draw water up away from your plant’s roots like a wick.
It is not uncommon, depending on the type and volume of seeds that you purchased, to have leftovers. Seed can remain viable for many years if stored properly. The germination rate will decrease over time, but it can definitely be used in the following season, if not many seasons to come. Once you have finished seeding a variety, put any leftover seeds into an airtight container, or plastic food storage bag, and be sure to label it with the variety and species information, the date, and any other pertinent information from the label that you will not likely remember. You will then want to store those saved seed in a cool, dark, and dry location.
A refrigerator works great for this purpose; some folks even store seed in their freezer, though not all seeds will handle being frozen. A basement can work too, so long as it is dry, does not let in much light, and does not get above about 50 degrees F (10 degrees C). You want to mimic the conditions that a seed goes through from winter dormancy to spring growth. To keep the humidity low within the seed container, you can either place a silica gel packet, such as the once you get in many shipped packages, or use a tissue wrapped around a teaspoon (5 grams) of powdered milk. This will also help absorb moisture in the storage container.
When you are ready to plant them again for the next crop rotation, season, or year, keep them out at room temperature for a while until they assume the ambient air temperature before sowing. Continue to store any leftover seeds as described above.
Finally, it is good practice to keep records of the entire seeding, germinating, and transplanting process. This will help you to make future decisions based on the successes or failures of your crop or plant production. The most learned horticulturists and the most esteemed resources can tell you how to grow plants, but your environment is unique and filled with microclimates. Good record keeping will help to guide future actions in order to keep having more success with growing plants and more bountiful harvests.