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Although seeds are essentially compostable, most composters and gardeners shy away from them due to concerns about seedling growth and spread. You can minimize this issue by correctly preparing your leftover or spare seeds and maintaining high temperatures in the pile.
Hot compost systems are suitable for processing seed scraps. Heat from hot piles can eliminate seeds, but as a precaution, you can pulverize or scorch them before composting activity.
If you notice unwanted plants sprouting on top of the pile, turn your compost vigorously until the plants are trampled at the bottom. This step will disrupt the lifecycle of the plants.
Read more to find out the best practices for successfully incorporating seeds in your compost.
How to Compost Seeds
Seeds are technically compostable, but without proper preparation and optimal pile temperatures, the seeds can sprout and survive in your compost pile. They could then spread to your garden and flower beds when you apply the finished compost.
For this reason, most composters exclude seeds from their compost to avoid accidental or unintentional germination — especially of weed seeds.
Preparing Seeds for Composting
Take precautionary measures by killing the seeds prior to your composting activity.
Using a blender or food processor, you can pulverize the seeds, effectively preventing them from sprouting in your bin or pile. Doing so will accelerate the decomposition of larger, tougher seeds like avocado pits. As an alternative, use a kitchen knife to chop large chunks of seeds in smaller pieces.
You can also scorch your seeds under the sun for 2 to 3 weeks until crisp and dry. For instance, seeds from invasive weeds will not survive the intense heat, preventing accidental growth in the pile and garden.
After these preparations, mix your seed waste with other compost materials.
Be aware — seeds have both carbon and nitrogen. When composting, sustain the best compost conditions below.
Optimal Composting Conditions for Seeds
Stick to the ideal 30:1 carbon to nitrogen ratio, ensuring the best compost quality. Carbon from “brown” materials such as dried leaves, shredded cardboard, newspaper, egg carton, untreated sawdust, and wood chips, provides energy to composting microorganisms. Coffee grounds and other fruit scraps and vegetable trimming support healthy development of these microorganisms due to their nitrogen content.
Sustained microbial activity from the balanced mix of organic wastes will increase the pile’s efficiency.
Keep your compost wet, but soggy. Too much moisture and lack of air triggers anaerobic decomposition, which can cause putrid odors. In contrast, a dehydrated compost pile will result in slow decomposition. Combat this issue by adding water or more nitrogen-rich compost materials.
If you notice excess fluids and off-putting smells, incorporate additional brown material to your bin or pile.
A hot composting system is excellent for seed waste. The internal temperature of a hot pile should reach anywhere between 130 and 170 degrees Fahrenheit. Within this temperature range, you can safely transform seeds and other organic matter into a nutrient-rich soil amendment.
Turning or stirring a hot pile frequently will improve air circulation and disrupt the growth of seedlings (if any). Young sprouts on top of the compost pile will end up at the bottom after turning, effectively impeding their growth. You can do this by using an outdoor pitchfork or a shovel.
Ideally, integrate seeds at the bottom center of the hot pile, where the most intense heat is.
How Long Do Seeds Take to Compost?
Your compost’s conditions and preparation will determine the decomposition rate of the seeds. In a well-managed hot pile, seeds can break down in less than a year. Keep the pile aerated, maintain the optimal temperature range, and balance moisture levels to successfully yield compost from seeds and other organic matter.
How Seeds Affect the Composting Process
Seeds contain carbon that improves the overall composting process.
Impact on Decomposition
When prepared correctly, seeds can decompose easily. Chopped or pulverized seeds decompose relatively fast compared to whole seeds. As a general composting rule, smaller organic materials are quicker to break down because microorganisms can consume them effortlessly.
Correctly preparing your seeds prior to composting will definitely save you precious time and prevent sprout issues.
As discussed earlier, seeds provide both carbon and nitrogen to your compost pile. These elements primarily fuel the pile’s microbial action.
It’s important to protect your compost’s microorganisms from seeds that have been chemically treated. The toxins from these seeds could seep into your compost and damage the microorganisms.
Temperature and Moisture
Continuous microbial activity will lead to a temperature increase in your compost pile. A balanced proportion of seeds and other organic matter helps promote such activity.
Fresh fruit seeds contribute very little moisture, while scorched ones provide none. To prevent a soggy compost pile, make sure to turn the material regularly. Moreover, maintaining adequate air circulation will help control your compost’s internal temperature.
Potential Issues With Composting Seeds
Unintentional growth of seedlings and possible pest problems are primary concerns with composting seeds.
Will Composting Seeds Attract Pests?
Adding seeds to your compost bin or pile can attract certain insects, such as beetles, borers, and weevils. Seeds already infested with other pests should be handled with caution. Some pests can survive the composting process (especially if you fail to achieve the optimum temperature range). To minimize pest problems, bury seed waste at the bottom center of your compost bin or pile where uninvited critters will have a hard time reaching them.
You can also cover your compost pile with a sheet of board or plywood to keep these critters.
Will Composting Seeds Cause Odors?
In a well-maintained compost pile, seeds do not cause bad odors.
However, anaerobic conditions like excess liquids and lack of oxygen prompt anaerobic decomposition, linked to unpleasant smells. To avoid this issue, follow the best management practices.
Methods for Composting Seeds
Not all composting methods are suitable for seeds. Explore your options below and see what works best for you!
You can safely include seeds in a hot compost system. In fact, it may be the best option for handling seeds due to the hot temperatures, but a hot compost pile is more difficult to maintain. Some composters and gardeners might find the temperature checks and regular turning laborious.
Hot composting involves composting microorganisms, their activity, and the consequent heat to effectively break down organic matter. Due to high temperatures, a hot pile produces compost faster than most methods. Proper air circulation and a balanced combination of brown and green materials are necessary to the successful hot compost of seeds and other organic material.
Seeds are not usually included in cold compost systems.
Cold piles lack the heat needed to kill seeds and are prone to unintentional growth and spread of seedlings. To avoid this issue, correctly prepare your seed waste by grinding or pulverizing them first. Or scorch your seeds with sunlight for a few weeks (until crisp).
Cold piles require minimal human intervention. The primary agents of decomposition are naturally occurring microbes, stray insects, and other environmental conditions. Because cold piles do not heat up, they take a longer time to produce compost.
Recent research encourages the additions of fruit and vegetable seeds in the worms’ diet.
Vermicomposting relies on the activity of worms as they consume decomposing organic matter. The resulting worm castings can be added to your garden soil, boosting its nutrient content. Gradually introduce small amounts of grounded seeds and provide other food sources to keep your worm farm healthy.
If you notice seedlings sprouting out of your worm bin, do not worry. Worms would consume the seedlings, too. Simply cut or shrivel the seedlings and they will start to decompose, attracting worms for consumption.
Avoid chemically treated seeds to protect your worm farm from toxins. Additionally, discard disease- and pest-infested seeds that can harm your worm farm.
Although seeds are fine to include in a Bokashi bucket, they do not add any valuable nutrients for fermenting microbes derived from the Bokashi inoculant bran.
The Bokashi method is a favorite among composters who have limited garden or outdoor space. In contrast to other techniques Bokashi promotes the anaerobic decomposition of organic matter. The fermenting microbes, in the absence of oxygen, break down food waste until compost is fully fermented.
If you decide to add seeds to your Bokashi bucket, prepare them in the same way you would for traditional composting. To neutralize the seeds, ferment organic waste and other food scraps for longer periods.
Alternatives to Composting Seeds
If you don’t have a home compost, consider sending or dropping off your seed waste at a composting center. Alternatively, use them to cultivate new plants.
Industrial Composting of Seeds
Large-scale commercial centers offer composting services to neighborhoods and businesses as an alternative to a traditional home compost system. These facilities are capable of maintaining hot temperatures, removing the risk of accidental sprouts in the compost. The finished compost is typically used in agriculture and various industries.
Reach out to the nearest composting facility in your area to learn more about how they accept seed waste. Keep in mind — these types of facilities differ in their guidelines on accepting organic household wastes.
Spare seeds not more than a year old and stored in a cool, dry place, can be forwarded to food and shelter organizations and seed banks.
For instance, Slow Food USA® offers a Share a Seed program initiative wherein seed donations across the United States are accepted. The organization has local chapters such as Slow Food DC, Slow Food Denver, Slow Food Las Vegas, and Slow Food Springfield.
Support food resilience and give the gift of growing by heading to their page to learn more.
Feeding Seeds to Chickens and Livestock
Some seeds can be fed to chickens. For instance, soybean seeds can provide amino acids to your poultry, while sunflower seeds are excellent protein sources. Flax seeds are rich in omega-3 fatty acids, but can affect the flavor of your hen’s eggs and darken the yolks.
You can mix moderate amounts of ground seeds in your chickens’ regular feed, but avoid chemically treated seeds to prevent health risks.
In a study, sunflower seed meal can increase the caloric energy of cows and consequently, boost their milk production.
Seed-feeding your livestock should be done carefully and moderately, however. Keep in mind that seeds alone will not cover all the nutritional needs of your animals.
Disposal Options for Seeds
If you cannot compost, or upcycle seeds at home, collect them in a nonbiodegradable bag and dispose of them in an appropriate waste bin.
What Seeds Shouldn’t Be Composted?
Discard seeds that are disease- and pest-infested to avoid contaminating your compost. Some of these diseases and critters can survive the composting process and possibly spread in your garden after the homemade compost is applied.
Carefully prepare seeds from invasive weeds before composting. If you’re unable to kill them prior to composting and fail to attain optimal temperatures during composting, you risk spreading the seeds in your compost and garden.
Omit chemically treated seeds, mainly if you aim for an entirely organic compost. Residues from herbicides and pesticides can leak into your compost and harm beneficial microorganisms.
Safety and Precautions When Composting Seeds
Sustain ideal compost conditions and practice the best pile management guidelines when composting seed wastes.
Handle moldy seeds with care. Wear a protective mask and a pair of gloves, especially if you have preexisting immunity or respiratory problems. Some molds produce mycotoxins that can threaten your health.
After composting activity, wash your hands over running water with soap.
How do I prevent seeds from sprouting in my compost pile?
Chopping, grinding, or pulverizing seeds will speed up their decomposition and prevent sprouting issues. You can also scorch seeds under the sun for 2 to 3 weeks, especially seeds from invasive weeds.
Can I compost salted seeds?
You can include salted seeds — like salted sunflower seeds — in your compost pile. However, do so in moderation as excessive salty seeds can throw off the pile’s salinity, potentially harming valuable microorganisms. Rinsing the salted seeds before composting can help wash away their salt content. In addition, rinsing will moisturize the seeds, aiding with decomposition.
What is the best compost method for seeds?
Hot composting is the best method when handling seeds. It generates enough heat to ensure immediate decomposition of seeds and minimize the likelihood of seedling sprouts. Hot piles should be anywhere between 130 and 170 degrees Fahrenheit.