Cover crops for unused garden plot?

I have a large veggie garden (60’x120’) and I’m not going to have the time this year to fill up the entire space with plants so I’d like to put down some cover crops to keep the weeds at bay and improve the soil.

Does anyone have any recommendations for something I can plant in the spring and not do anything with all season long, and then have tilled under next spring? In other words, I don’t want to have to mow it or do anything else other than plant it and forget it! Bonus for things that are good for pollinators or birds.


buckwheat. its a N fixer and grows fast. maybe mix in some alfalfa too as buckwheat will start to lay down as it matures and the alfalfa will keep the weeds from coming in under it.


bumbles love flowers of both of these. i even grow Japanese red Takane buckwheat in my flower beds. got the seeds from

Buckwheat matures in less than 3 months, and then there will be buckwheat seedlings in that plot for many years. I suggest sorghum instead, scythed when it is about to set seed, and eventually replanted with something like daikon or oats that are winter killed. This not only gives biomass, but also deep root channels. You could also plant sunflower with sorghum, and manage it similarly. If your cover crop is annual it will set seed and you will have a problem next year. If it is biennial or able to overwinter it will come up next year, which is undesirable too. so some management is needed. scything and replanting is the minimum work approach.


Im a bird lover and pollinator guy myself. I would get a couple of packs of mexican sunflower seed and a handfull or two of black oil and striped sunflower and enjoy the show.

edit- i like the cheapo 4 packs for $1 zinnias too… they have deep roots and alot of enjoyment for a few bucks.


if tilled under in the fall and till it again in the spring after the seeds start to germinate. it will kill them off. ive done it before in my raised beds. or could go over them with a high mower deck just as the blooms start to fade before they make seed.

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Hi Bart,
I would look for the cheapest seeds among the following: Crimsom clover, buckwheat, rye, or alfalfa. Chances are crimsom clover will add more nitrogen to the soil than the others for the money. If you plan to let the cover grow this winter, let them go to seed and till under this fall for a winter cover crop.
Kent, wa

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I love cover crops, but with what you’re suggesting I’d be worried about putting out too much seed over time if you really just want to plant it and leave it until next Spring. Overall, while I always prefer to plant a mix instead of just one type, in this case I’d suggest looking at some of the Sorghum Sudan hybrids that are sterile. It is best if you cut it a few times during the season, which will give you more biomass and a denser stand, but even if you don’t do that it will get very tall and shade out a lot of weeds below and then it will die at first frost. Also, it will put out some sorgoleone through the roots which is a natural weed inhibitor.

The only concern I’d have is it the dry stalks might be too much for your tiller in the spring. I don’t till, so I don’t really know what bothers a tiller or not. It would probably be best if you could knock it down late fall when its dead and it might break down more if it is on the ground before your spring till

Frankly, if you have enough, someone with animals might be interested in cutting it down in the early fall for them to use as feed. you’d still get a lot of value from the stub stems and the big root systems.

I’ve been really happy with advice I’ve gotten on a few things and the seed from Green Cover seed, but you’d have to call them to find out which ones are sterile.

Here’s one example from another vendor that does specifically state it is sterile:


I would second the Sudan grass suggestion.
Needs a good dose of fertilizer for best organic matter production, it can get 12 ft tall , choke out all weeds .
Maybe cow peas for a shorter nitrogen fixer.
@steveb4 , Buckwheat is NOT a nitrogen fixer .

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Thanks all! Great suggestions as usual, but more complex than I was hoping for!! :rofl:

I always plant tons of sunflowers and planned to branch into zinneas this year but I’ve worried about the sunflowers shading the other crops so I’ve segregated them to one part of the garden. Looks like If I ignore the cover crops for the entire season, I could be facing some of the same issues.

There are always trade offs I guess!!!

Thanks again for all the suggestions (and warnings!)


They all are nitrogen fixers, if you are willing to wait. Sorghum residue can only decay if the bacteria eating it pull nitrogen from the air. As such, over a year sorghum (or sunflower) fix more nitrogen than clover, essentially because they fix more carbon. IMHO, deep root channels are really important in heavy soils. See the two ebooks below. If you go highest biomass/carbon/nitrogen, it is useful to use the bed next year on crops that can be planted through mulch, like tomatoes or squash.

hmm. i stand corrected. i thought i read somewhere that it was.

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I like buckwheat as a quick short term ,cover crop .
Good to smother weeds , great beneficial insect habitat.
The amount of organic matter that it produces is a illusion.
The dry weight of it doesn’t amount to much, it’s mostly made up of very juicy stems ,leaves. Quick to decompose, so may be beneficial to soil microbes. Hard to find seeds here.
Only good for about two months, not the entire season

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famers grow it here to make buckwheat flour. they often mix in alfalfa with it. fields are a crimson red when its ripe. i can get seeds for very cheap here. our seasons only from mid june to the beg. of oct. after harvesting the buckwheat they leave the alfalfa until late sept then till it under.

Forage collards. They won’t mature and set seed until they’ve vernalized. Impact Forage Collards » Green Cover

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ive seen this in fields around here but didnt know what it was. recognized it from the flowers.

Buckwheat is not a legume, and is not a nitrogen fixer. However, it does scavenge nitrogen deep in the soil and returns it up to the top of the soil due to deep roots. When it dies, the nitrogen is then in the upper levels of the soil and available to other plants with shallower roots.

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Worth noting that in short-season areas turning in large amounts of organic material in the fall can tie up nitrogen in the spring.


Agreed on the buckwheat residue, short term weed smotherer, but not much residue to keep them down. Which could be a positive in some scenarios. I like vetch for a similar reason, grows like crazy and then decays very quickly. So we can work the ground earlier than crimson clover or a grass.

I don’t know if it would be a problem with tightly spaced collards for cover crop, but brassicas can leave behind quite a trunk that takes forever to rot.

Guess I’ll alter my last statement, I love Asian brassicas for cover. Only problem is that they will host cabbage aphid, but a lot less than European brassicas do.

This is komatsuna, which has similar benefits to buckwheat but provides salads for a long season and then the bees love it after that. It also takes much longer to set seed than buckwheat, but smothers just as well. There was daikon mixed in there too but than even got smothered by the komatsuna. Bok choy and mustards works well too, but don’t have the speed of the komatsuna, so I mix it in.