Why Are Vegetables Popping Up In Compost Pile?
Seeds sprouting up in compost? I admit it. I am lazy. As a result, I often get some errant veggies or other plants popping up in my compost. While this is of no particular concern to me (I just pull them up), some folks are a bit more disquieted by this phenomena and wonder how to prevent seeds from sprouting in their compost.
Why Are Vegetables Popping Up in Compost?
The simple answer to “why are vegetables popping up in compost” is because you are composting seeds, or rather not composting them. You either belong to the lazy group of people, such as myself, and just toss everything into your compost, or your compost is not super heating to a high enough temperature that will deter the seeds sprouting in compost.
How to Prevent Veggie Sprouts in Compost
Keep in mind the mechanics of the compost pile. In order to keep seeds from sprouting in the compost pile, it must attain a temperature between 130-170 degrees F. (54-76 C.) and must continually be turned if temps drop below 100 degrees F. (37 C.). A properly heated compost pile will kill off the seeds, but does require some serious vigilance and effort.
Along with moisture and turning the compost pile, the proper levels of carbon and nitrogen need to be present for the pile to heat up. Carbon is produced from browns, such as dead leaves, while nitrogen is produced from green waste like grass clippings. The basic rule of thumb for a compost pile is 2-4 parts carbon to one part nitrogen to allow the pile to properly heat up. Chop up any large chunks and keep turning the pile, adding moisture as needed.
Additionally, the pile should have enough space for successful composting to take place. A compost bin will work or a pile 3 feet (1 m.) square (27 cubic feet (8 m.)) should allow enough space for composting seeds and killing them off. Build the compost pile all at one time and wait until the pile drops before adding new material. Turn the pile once a week with a garden fork or a compost crank. Once the pile has composted in its entirety- the material looks like deep brown soil with no identifiable organics- allow it to sit for 2 weeks without turning before using in the garden.
If you are practicing “cool composting” (AKA “lazy composting”), which is simply piling up the detritus and letting it rot, the temperature of the pile will never get hot enough to kill seeds. Your options then are to pull the unwanted plants “ala moi” or avoid adding any seeds into the mixture. I must say that I do avoid adding certain mature weeds because those I do not want spread all over the yard. We also do not put in any “sticker” plants into the compost pile, such as blackberries.
Can You Use Seedlings from Compost?
Well, sure. Some “volunteers” from the compost bin yield perfectly edible veggies like cukes, tomatoes, and even pumpkins. If the stray plants don’t bother you, don’t pull them out. Just let them grow through the season and, who knows, you may be harvesting bonus fruits or vegetables.
Occasionally, errant veggies or other plants pop up in compost. While of no particular concern, some folks are a bit disquieted by this and wonder how to prevent seeds from sprouting in their compost. This article will help with that.
Effect of sprouts in compost
My compost always has lots of squash seeds in it, and invariably, many of them sprout in the Springtime. Sometimes I’ll grow out one or two to see what I get, but I turn most of them back in.
My question is. does a 4-6″ squash seedling add anything to my compost that the original seed did not? For instance, did that little plant pull nitrogen out of the air, which is now going back into my compost? Did it just use what was already there, and have no net effect? Did some of the good stuff in the compost get lost, because no system is perfectly efficient?
Does anyone know? Tell me more!
The occasional seedling will have virtually no effect either way because it is a tiny fraction of the entire pile. That said, it is basically pulling water and nutrients out of the compost, and CO2 out of the air to make more plant fiber as it grows. If you turn it back in, the nutrients are recycled, and the tiny bit of extra CO2-derived fiber is added to the pile.
It’s negligible, but yes, plant seedling will add something to the pile that wasn’t already there. That’s part of the beauty of photosynthesis. Plants turn sunlight in to nice stuff 🙂
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Compost consists of, or should, mostly vegetative waste. Seed sprouts are vegetative and so contribute to the basic needs of the compost pile. If these seedlings are on the top of the pile they can be turned in or covered with more material. Seeds, which contain everything the plant that could grow from it will need until the plant grows enough to start photosynthesizing, are a good addition to compost in spite of all the negatinves you might hear.
kimmsr, that wasn’t quite what I was asking.
I understand that both seeds and seedlings add beneficial ingredients to the compost pile. What I’m wondering about is what might be different between the ingredients un-sprouted seed, and the resulting young plant, assuming the plant sprouted from within the same compost pile.
If the seed rots before it sprouts, or rots after it sprouts, what is the net effect?
The conservation of mass theory sort of comes into play. If a seed sprouts and grows, then some matter is being technically added to the overall compost pile. Unless it is a ‘nitrogen fixing’ species, it is unlikely to add much more than some carbon which all plants get from the atmosphere.
If the plant were to develop a fruit/seed and this was harvested, then there would be a loss of some nutrients. Water vapour wold also be technically lost due to evapotranspiration but this is compensated for by watering so no big deal.
Adding seed materials to a compost pile isn’t a bad thing unless those seeds are still viable when the compost is ready to be used. This is one big reason high temperatures and/or extended curing periods are desirable.
Yeah, Lloyd, I’m just not clear on how much of a plant’s “stuff” is coming from the air vs. the soil. I also feel like the soil-to-plant process can’t be 100% efficient (since nothing is), so surely something is lost?
My compost always has viable seeds still in it, and I know it. At least a fair number of the squashes take care of themselves by sprouting before the compost is done! I avoid adding seeds of the nasty invasives, and for the rest, I just shrug and go for the “coffee and beer” weeding method mentioned in another thread. I tend to grow out a few volunteers every year, too, just to see what I get. It’s always been informative, and usually quite tasty.
The vast majority (95%?) of the mass of a plant is carbohydrate-based fiber and water. How much of the carbon in those carbohydrates comes from the air in that situation, I don’t know. For a mature tree, virtually all of the added mass each growing season is from water plus CO2 from the air. With a seedling, it’s feeding on its seed as well as the surrounding soil.
This is a bit like speculating how many angels can fit on the end of a pitchfork tine. Nothing wrong with that though. :-]
If the plant is going to be re-composted, the nutrients pulled from the compost stays in the compost (unless an animal/insect eats part of the plant and makes off with it). As tox states most plants are made up of carbon pulled from the atmosphere so that would be an addition. Some nutrients can be added via raindrops but these would be so minuscule as to defy measurement but showers during thunderstorms can add nitrogen.
Sorry you asked yet? 😉
I’ve got lots of squash sprouts in my lazy compost pile and had been turning them back into the pile until I started wondering why I couldn’t cook them or wash them off and put in my smoothies. anyone tried that?
No I haven’t, but it would depend on what was in the compost and how icky it was. I would definitely not do that if there was manure in there, or fairly fresh rotten foods with a bad odor. Compost is teeming with microbes, even more than soil which has millions or even billions per gram. Some of them are not too good for you. Now if the pile is pretty old and isn’t anaerobic but is earthy smelling, it’s probably fine. And if you’re eating leafy parts rather than roots, the exposure is pretty minimal even before washing.
One of the best cuke vines I ever grew came out of a compost pile. I remember on a hot summer day harvesting 13 cukes at once. They grew so fast you had to keep up.
I always get cucumber to grow from the compost, tomatos, papaya, guavas, a few mangos, this one I just pulled out and transplanted as I treasure an extra mango tree. I do direct compost, in a large pot I put about 2 inches of soil, then add about 10kg (that I freeze little by liitle) of all the fruits and veggies that I use, I run detox retreats in mexico so I can gather a lot of organic material very quickly. So then I put about 2 more inches of soil on the top. I repeat this process until the pot is almost full, then I plant a tree about 2 years old on top, and they grow very happy. Beware, I put Taro in my compost and it started growing like crazy but the leaves are toxic unless cooked super well. it was growing on a hand of buddha lemon tree and when I pulled it out my hand a buddha died a couple of weeks later, I am wondering if the toxic milk from Taro mixed got to the root of my tree. Besides that one all trees growing super happy.
My compost always has lots of squash seeds in it, and invariably, many of them sprout in the Springtime. Sometimes I'll grow out one or two to see what I get, but I turn most of them back in. My question is…does a 4-6" squash seedling add anything to my compost that the original seed did not?…