Do Seed Bombs Work? (I Kind of Don’t Think So)

Do Seed Bombs Work?

Do Seed Bombs Work?

I feel terrible about saying this out loud, but it’s been bothering me for a VERY long time, and I finally just have to admit it:

Y’all? I kind of don’t think that seed bombs work.

So, Seed Bomb 101 for those who aren’t as obsessed as I am: seed bombs are little balls of compost and clay (or sometimes papier mache) with seeds embedded. The theory goes that you toss them in a neglected green space as an act of guerilla gardening; the clay keeps the seeds moist as they germinate, the compost nourishes them, and they grow, implanting themselves into that green space, making it pretty, and providing valuable food for bees and birds.

It sounds so lovely, doesn’t it? And it’s an easy craft, perfect for preschoolers or day camps or Girl Scout troops (which is how my obsession began, researching activities for the Junior Flowers badge for my troop).

And the seed bombs are pretty, so they make lovely party favors or wedding favors or homemade gifts.

Except… Science.

Here are my two Scientifical Concerns, which I would love, by the way, to have Scientifically Rebutted by a knowledgeable commentor so that my Girl Scouts can go ahead and make their dang seed bombs, already!

1. Germination. Seeds require moisture to germinate. Germination is a delicate process, however, and if the seed dries out while in the process of germination, then germination ceases and the seed dies. This is why you have to keep the soil moist when you’re starting seeds, and why those little greenhouse roofs that you can put over seed starting flats are so handy.

Recipes for making seed bombs require moisture. The most common type of recipe calls for compost mixed with a clay slurry and formed into a ball in which the seeds are embedded. Then, you generally let the clay dry out–the understanding, with most of these tutes, is that the seed bomb is then “shelf-stable” and can be used at your leisure.

Another variation on this recipe uses paper instead of clay and compost–essentially, you mold papier mache and insert or stick the seeds to it, then let it dry.

To my mind, then, this moist environment of the seed bomb begins the seed’s germination. If you then let the seed bomb dry out, or even if you toss it while damp into a green space that then does not immediately get some good rain showers, the seeds will cease germination and die.

So the seed bomb doesn’t work, at least not as generally advertised.

2. Overseeding. Let’s say that it does work. Here’s my next problem:

Many seed bomb tutorials call for a mix of seeds, and they call for many seeds per seed bomb. This means that even if the seed bomb worked exactly as advertised, what would sprout will be six to a dozen or more seedlings, of different types, all in about an inch of green space.

Well, they’ll strangle each other, right?

A lot of my doubt is stoked by the fact that I can’t find many seed bomb success stories online, nor do I know by word of mouth of any acquaintances who can tell me seed bomb success stories. Mind you, I have seen a couple of success stories online, and this has inspired me to think that perhaps, with exactly the right structure under exactly the right circumstances, seed bombs *could* work, and I’ve got a couple of experiments in progress, one that requires the seed bombs to be made and then deposited immediately, with rain imminent, and another that uses only dry materials, but mostly, for most seed bombs under most circumstances, I suspect that they’re just a fun thing to make, that makes you feel good but has little effect.

Am I wrong? Tell me that I am! Give me anecdotes! Give me evidence! Be very Scientifical in your speech, so that I believe!

Photo credit: seed bomb image via Shutterstock

47 thoughts on “Do Seed Bombs Work? (I Kind of Don’t Think So)”

  1. I have no experience with seed bombs, but I’ve always had the same concerns about them. Having started many seeds over the years, it doesn’t make sense that they would be effective.

  2. Hey Julie, your concerns are very warranted. And, your thought process is really quite on track regarding seed balls and their germination. There are a few items within your theory that don’t quite pan out from our experience. We’ve made over 150,000 seed balls in our journey to grow one billion wildflowers and have a consistent 80-90% germination rate. FIRST, the compost to clay ratio has to be correct. Many recipes online advertise 5 parts clay to 3 parts compost and 1 part seed. This simply doesn’t work from our tests, too much clay, dries out too quickly, and is too hard for seeds to sprout from. Another set of recipes recommend 1:1 ratio of compost to clay. This is a little bit better and more on track. We’ve found the ratio that works best for us is 4 parts compost to 1 part powdered clay by weight(very important to do it by weight). The compost needs to be somewhat moist, but not wet by any means). Also, the quantity of seed depends on the type, a cup of poppy seeds can contain over 100,000 seeds, whereas a cup of sunflower seeds may only be 500-1000. SECOND, The natural conditions when you throw them out must be favorable to germination. People who throw them out in the middle of the summer with no supplemental watering might as well wait until fall rains come, because that’s when they will sprout and take hold. If planting in the spring we recommend to plant them after the last frost but before the regular rains stop. We also recommend planting them half-way into the ground if your area is particularly dry, so they can benefit from extra ground moisture. If planting in the fall, plant at least 10 weeks before the first frost so they can germinate and take hold, thus producing better blooms in the spring. THIRD, the germination period is much different than many people expect. I’ve thrown seedballs in the spring behind one house and nothing happened all summer and all fall. However, the following spring I saw wildflowers all over the backyard where we put seed balls. Under ideal conditions some of the seeds should germinate and sprout in about a week. (A number of the seeds may never germinate, even under ideal conditions – that being the nature of Nature.) FOURTH – Competition and sprouting, many seedballs contain a variety of seeds inside one ball, you may think this is too much in one. It’s not, from our experience some get out-competed, and some never fully mature, but the seeds that are meant to be in that spot grow up and take hold. I’ve seen lupine, poppy, bachelor button and black eyed susan all come from the same 2 square inch spot and be growing well together. Anywhoo, figured I would share our story, as we’re passionate about seed balls and bringing back the bees by growing the rainbow.

    1. Thanks for that info Chris. Have you found paper mache bombs also sprout, even if less successfully than compost + clay? Thinking of making some as gifts and paper mache suits better than using dirt.

    2. Hi there. I Am very interested and I like your clever practicle reply to the guy who seems clever buy with no much of real experience. I would like to ask you if you have experience with trees. I want to try with oak tree cause here (Bulgaria) is quite everywhere and do you know when the trees are actualy starting the germination process, in the automn or spring? Please write me e mail if possible if you have answers to those questions – Big thanks and if something doesnt work, find out why and fix it 🙂

    3. thanks but what about throwing the seed bombs over mulch? I wouldn’t want to move my mulch out of the way then back into place. HELP!

  3. I agree with Chris and have had the same results. Most seed bomb recipes call for waaaay too much clay! My first time with making them, I ended up with “rocks” that never wanted to soften no matter how wet they stayed.
    Weather and environment plays a big part so if one lives where you can somewhat trust in what your weatherman is calling for – then seedbombs will make it.
    Here in Kansas, it’s a huge gamble if you’re trying to beautify an old lot or alleyway.
    Rain never comes when they call for it…never. So unless you want to haul water to that old lot or alley – don’t try for seedlings this year but hope they succeed on sprouting the following Spring.

    I had actually thrown some seedballs 2 years ago next to an old canal/waterway in the grassy area, using seeds of common prairie wildflowers known in this State. (flowers that re-seed themselves and can thrive on next to no water.
    First year, nothing. But last year and this, the seedlings sprouted and bloomed in mass!

    Seed bombs work fantastic if you use them to plant your own garden (Vegetable & flowers) and I have yet to even attempt to bury them. Just lightly water each day and then once sprouted – as you would for any seedlings you’ve hand planted.

    You should read this article
    He is the original creator of clay seed balls – creating edible vegetation in areas that were bare and void, using only nature.

  4. Hey Julie, Have you actually tried this or just going with your intuition?

    I can understand your concerns about water and “damage” but need to see some data. The other comments certainly advocate for the method.

    I am going to run an experiment in my garden under somewhat controlled conditions and will post the results.
    ~ I am planting 3 rows
    ~ One row is 1/3 of the seeds planted conventionally.
    ~ One row is 1/3 of the seeds placed using chris’s technique
    ~ One row is 1/3 of the seeds placed using the gel cap technique.

    I’ll water all the same.

    Now, I sure understand that the growing environment (brown field) has a LOT to do with success or failure but I am interested if the inherent seed bomb technique actual renders the seeds “sterile” per your article.

    1. Ooh, definitely try it! I made it clear in my post that my hesitations are based on intuition about my understanding of the way that seeds sprout, so experiments are always welcome. Def post your results!

  5. Haven’t tried seed balls but hope to. What I know is that most wild flower seeds germinate if given just a chance. Cosmos, for example, will come back every year with no intervention. Fact is they’ll come up a hundred feet from the nearest plant. A little moisture and a shadow of cover seems all they need.

  6. We made some little papier mache ones at school because I thought it would be cleaner..and they started sprouting within a couple of days while we were trying to dry them out to sell at our Easter Fayre, so I recommend using old newspapers. We ended up selling them in pots ready to put outside or grow in the pot. I used some free packets of wildflower seeds and some old packets of hardy annuals which were out of date and was pleasantly surprised.

    1. Do you mind posting your recipe? I am interested in making some for an easy party favor but like the originator of this blog I feel like it might be a waste of time and I don’t want to give something that isn’t going to sprout. I appreciate your time.

  7. Katelynn Turner

    Throwing seed bombs lets people feel satisfied with themselves for little effort, but cluster-planting on property that doesn’t belong to you is littering, and the plants are indistinguishable from weeds at a distance.

    1. Weeds don’t exist. Everything is a plant. You call it a weed because you don’t like how it grows. I’m. It saying this with attitude or anything and I’m not trying to be mean. It’s just a fact. A “weed” isn’t actually a scientific word that classifies any plant. So a “weed” is just something you don’t want growing.

  8. I just watched a short clip on Facebook on how to make a seed bomb. Then the little girl flung the bombs with joy on her face, I wondered why they didn’t follow up with water or covering them with dirt. This led me to you when I couldn’t find a different ending anywhere. Thank you for confirmation on my immediate concern for the little seeds trapped in a hard ball with no chance for escape.

    1. Just give it a try. The seeds escape spouting. We use seed balls for reforestation in Portugal since years. Once in a early summer I threw out a handful remained seed balls in our garden with no any idea that something may happen. Two years later I had to dig out well grown oaks.

      1. Hi, Bernardo. Please let me know about your experience with reforestation with seedballs. I have started doing this in Bulgaria and. I would love to hear about your experience. Big thanks budy.

      2. I know this is an old post, but I am currently doing reforestation work and we want to get away from using the plastic pots and we’ve been research seed bombs. What is the name of your project?

  9. I work at a makerspace in a museum and I’m planning on making seed bombs for a family art/ earth day program. Like you, I was nervous about whether or not these bombs would actually go off (I didn’t want the kids to be disappointed). I was especially worried since my boss preferred we try the papier-mache version to make it more art project-y. I made a few trial bombs and left them still slightly damp in my boss’s office over the weekend (which has little natural sunlight) and surprise–when we came back on Monday they’d sprouted! I even have the photos to prove it…It frankly surprised the heck out of me that this actually worked. 🙂 I only used newspaper, water, gel food dye & dried flowers (for color), and california wildflower seeds. I pressed them into silicone cupcake molds, since that’s what I had at home so they didn’t dry out completely for a while which I think helped.

  10. When used for permaculture seed bombs/balls are great, but it’s ILLEGAL to dump seed bombs on private property. Dumping is a TRESPASS. Here’s what’s going on in my part of the upper middle class world: whenever a neighbor has a problem with another neighbor he or she bombards their neighbor’s house with seed bombs. Seed bombs not only ruin landscapes that cost thousands of dollars to plant but they also invite rodents. That’s correct–rats, white footed mice, brown mice, chipmunks, rabbits, squirrels, many birds and their predators are attracted to seed balls/bombs. The rodents chew up expensive roots on bushes, trees and herbaceous plants as they desperately try to eat all the seeds and moss. Rodent’s poop also attracts their predators, and those predators tear up the garden looking for rodents. As if this is not bad enough some have decided to throw glass shards inside the seed balls.

    Seed bombing private property, other than yours, could cause the destruction of property and it is illegally dumping. Dumping is against the law and a person can get a fine, arrested or sued for such acts. As for children, anyone teaching them to throw seed balls on private property other than their own, is encouraging bullying and unlawful behavior, and therefore corrupting minors.

    1. It sounds like they are creating some great wildlife habitat! You have a whole food chain in your garden, as it should be! Please read “bringing Nature Home” by Douglas Tallamy – an awesome book about useful gardening. The glass is quite extreme though… Sounds like you may have bigger problems than wildflowers in your community.

    2. You, my dear, remind me of a recent facebook post i read on my community page. I live in the country and we live in a current hot spot for city folks that have more money than sense to buy land build a house that is ridiculously huge and obviously new money because the houses are extremely gaudy. Then they have the nerve to complain about things in the country. Such as coyotes, rabbits, cows, donkeys, etc…..silly.

    3. That’s actually hilarious. I’ll make a note of that when I pass through an upper-middle class neighborhood that is so often a failure of urban development and a complete mismanagement of resources.

  11. Have you heard of Masanobu Fukuoka? He seeded fields this way for years and it worked. Check out his little green book, the One Straw Revolution..

  12. I’ve been making seed bombs for years and they do work! Just like everyone else said, use less clay and more compost, and the best compost you can get. I have compost I have been nurturing for years that is rich in beneficial microorganisms and worm castings. I also use some well-tested seed mixes that usually contain just 3-4 seed varieties of things that grow in harmony together. Want to try a cool mix for the fall? Use buckwheat, cilantro, vetch and radishes. Sow in late summer, 6-8 weeks before first frost. Your buckwheat will grow first, and wI’ll die in the frost, providing natural mulch for your cilantro and radishes. Your cilantro will help space your radish seeds and keep them hidden from critters. The vetch week chine on last, growing in the winter (at least here in NC) and will provide a winter cover for your garden and spring forage for bees.

  13. Apart from the one post where neighbours “bomb” each for snively reasons (I could see that happening here in Canada, too.), please be careful what seeds you try. Annual flowers are likely OK; invasive plants definitely aren’t. And there is the important issue of trespass that has been raised.
    One of our local problems is that “agronomy grasses” all planted for green mulch, bank stabilisers, etc., etc. good intentions easily out-compete native veggies or foreign flowers or the native species. I made the mistake a long time ago of using fall wheat (supposed to die off in winter, but no one talked about the seeds latent on the soil). The slope outside the blackberry area had an abundance of a suite of native flowers. Now, the native flowers struggle simply to survive (big decimation!). That has happened wholesale in southern Vancouver Island. I was glad the soil on the ex-blackberry kill zone was stabilised but have paid the cost repeatedly over the past 16 years. The only resolution, short of blasting with Roundup, is to mow 3x during the spring and summer to starve the wheat out — and that has slowly helped. But that area is a moderate slope, so now we hire someone to be our right arms. My wife and I will likely be pushing up rhodos long before there is any sense of victory.
    I say “Nuts to seed bombs!” I have read Fukuoka’s book and would try the mini versions for seeding veggies. No one I know talks about wrestling with run-away bok choi!

  14. I have planted seed bombs and they DO work in the right conditions. I live in Ireland. We did a workshop with the kids in the local school last year (beginning of June 2017). We made the seed bombs (mix of 2:1 compost to clay soil, wildflower seed mix and enough water to make the mix stick together) and left them to dry out for a day so they would be still moist inside but robust enough on the outside to hold together when thrown. I brought some leftovers home. The ones the kids threw out landed on dry, quite hard-packed ground. (We had had about a month of hot sunny weather with no rain.) The ones I brought home I tossed into long grass at base of trees and around the edge of veg patch. The ones at school received practically no water during a dry summer and did nothing. The ones at home I watered regularly during the same period and after about 2 weeks the most amazing display of wildflowers started appearing. They flowered from June to October and only stopped when winter storms lashed the hell out of them. Some species are starting to sprout again this year. So, lesson learned is seed bombs do work but they do need to be watered during dry spells or they won’t “take”.

  15. You don’t have to bother with “bombs”. Just collect seeds from plants like Cosmos, Zinnias, etc. Plants that produce enormous quantity of seeds that will germinate mostly barely covered or even lying uncovered come spring. Scatter in late fall and watch the show in spring. The thing is that these plants germinate easily and produce so many seeds that even 1 plant per 100 seed will in time produce thousands of wild growing flowers. Flowers that you plant once in a lifetime. Remember nature doesn’t till the soil to spread wild flowers not does it put seeds in “bombs”. Just scatters them around and depends on just one in many.

  16. Very nice post and discussion. Unfortunately discussion goes on whether seed bombs erficiently works or not. However my concern is more on: Once you wet the seed in the forming of clay or paper balls you dont let them already germinate? So if you make them and throw them away all the discussion above stays valid but if you make them and let wait 1 month what happens? You already kill the germinated seeds in the ball in the fırst 1-2 weeks (some might escape – nature of nature) and wait something dead to flowerish??? I think they will make great gift for occasions with many participants as they are colored and tiny, where comes the need to use them 1-3 months after they are made? Sure there should be more resistant seeds but still this is not the question.

  17. I think the point Chris has made needs further discussion. We are trying to make Seed bombs for local varieties of trees and find that during the period that the clay dries out the germination process also starts. That means that these are just seed ball rather than seed bombs and need to placed immediately for any chance of success. There seems to be little possibility of storing them. Any suggestions based on experience.

  18. Pingback: Bombs for Butterflies: Craft Milkweed Seed Bombs in Time for Fall Planting - Offbeet Gardener

  19. Seedbombs, I love the idea too. Alsi had some doubts. What about wildlife lunching on your seedbomb buffet? We had experiences planting seeds in a seeding tray at home, in a “protected” environment. Couple days later? Eho’s been digging in the seed trays? Seeds gone. We have Possums in Australia. 😉dirty little thieves. But they ate cute still.

  20. So, interesting; and based on my recent experience, very probably correct unfortunately. I bought some from my local Lidl store in the hope of bringing a bit of colour to a flower bed, but when I chucked them out I found the bombs themselves were as hard as bullets and no amount of watering could persuade them to dissolve. I thought about using a pressure hose on the things!
    A lovely idea, very symbolic and very worthwhile, but yeah, tend to agree. They just don’t work.

  21. I didn’t read through all the comments and I realize this post is 8+ years old, but I think the use of seeds of winter hardy perennials might be the intent, provided you distributed your bombs in the autumn, should address your germination concerns as you’d essentially be replicating what they’d need to go through during a winter.

    However, I’ve also wondered about the amount of seeds typically depicted in a bomb on most sites and, like you, thought too many germinating in a small space would only choke each other out.

    So, if you’ve actually tried this since 2015, I’d love to hear about your success and see photos.


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