Organic Gardening with Sue Robishaw
Four decades of Growing
in Michigan's Upper Peninsula
Do you compost with enthusiasm all year then find at the end a molehill instead of the mountain you want to spread on your garden? Do you find yourself considering outrageous schemes on how to collect those cow pies from the neighbor’s pastures, since you have no animals of your own? Do you have visions you’d rather not have when you hear the term "Green Manure"? Not to worry, help is on the way. And for once it doesn’t cost much in time or money.
Green manure is simply any crop grown to be turned into, or cut down to lay
on top of, the ground for the purpose of adding organic matter and nutrients to
the soil. No matter if your garden is ‘tiny small’ or ‘acres large’, you
can make use of green manure. Any part of your garden not growing a crop can be
growing some green manure.
NEW GARDEN AREAS
If you are starting a new garden, or expanding the one you already have,
green manure can make the job easier and add much appreciated organic matter to the
soil. Even if you plan on having permanent beds and working your plot by hand
later, a tiller can be a great help in the beginning. But this can also be done
by hand with a shovel, which would be more appropriate for a small plot or a
It is nice to give sections of your garden a rest and refreshment once in a
while. I often have a few beds out of production every year, growing just green
manure. How often depends on my schedule and how fertile the individual bed is.
I don’t get too fanatical about this, but I keep an eye on the soil and plants
as I work in the garden. I also look back at what was grown in a particular bed
in previous years when laying out my pre-season garden plan. If a bed has been
in production for a long time without a rest, I’ll plan on growing green
manure there the coming year. Most plots get a recuperative rest about one in
AN ABUNDANCE OF WEEDS
Weeds are just another green manure crop. The trouble with weeds is that they
are often tenacious perennials that don’t cooperate much in the "rot and
don’t regrow" idea of green manuring. However, I have been known to
handle an occasional overly weedy plot (we won’t say how occasionally) with
the dig and bury method. It’s not the best. It’s not going to get rid of all
the weeds and it is not going to get your garden in a glossy magazine. But it
will buy you some time. You would, of course, be better off to get down and get
dirty with hand to hand digging with a trowel. But, when you just don’t
want to, here’s an alternative.
If I haven't
been doing a good job of weeding, my strawberry beds tend to get inundated
with dandelions, grasses, and other perennials that are hard to remove from the
thick mat of strawberry roots. So I choose another plot and transplant runners
to start a new bed. After harvest is over in the old bed, I roughly turn the
plants over with a shovel, then plant green manure into the lumpy ground. I let
it grow, then cut it down in the late summer to settle and rot until next
ABANDONING A GARDEN
There may come a time when you decide to bring your garden down to a more manageable size. Or you want to move it to a new area. Instead of just leaving the old plots to grow over lumpy and bumpy, smooth the outgoing section with rake or tiller and plant a light nurse crop such as an annual grain, maybe with some clover, to keep things under control until the natural vegetation can take over. This isn’t exactly a green manure crop, but it’s similar and can help that old garden into its new life.
WHAT TO PLANT FOR GREEN MANURE?
Green manure seed can be just about any seed that you have or is available in your area, though some will be more appropriate than others. I have a variety of favorites. You can mail-order green manure seed, but because of the quantity and bulk of the seed used, that route is rather expensive and seldom necessary. Instead, check with local farmers or the local feed-mill. Tell them what it is for, and they should be able to give you an idea of what is commonly grown and available in the area. Buy bulk feed seed, not certified seed. You don’t need purebred -- regular everyday will do. You can also grow your own.
BUCKWHEAT is one of the main workhorses of my green manure crops. It produces
even in poor soil, it is easy to grow and cut down or turn in, and it’s
beautiful. Though not grown by farmers in our area as much now as in the past, I
can almost always get a bag of it at one feed store or another. A ten pound bag
will last quite a while. Its one drawback is that it is a tender crop and will
be killed by frost. So I use it as a summer green manure crop.
OATS are another favorite of mine. Wheat, barley, rye are similar to grow. But oats are readily and cheaply available here from farmer or feed mill. And oats winterkill better than the other grains, so I don’t have to worry about them regrowing next spring. Any of the grains can be planted early in the spring, and fairly late in the fall and still make some growth. They don’t give as much plant mass as other crops, but they are easy and reliable. I sometimes plant oats early, cut or dig in the crop a month later, then plant a mixture of oats and buckwheat in the trash, cut that down in about a month, and plant oats again.
I often plant oats in early to mid August to have something in the ground over winter. Oats winterkill so I don’t have to worry about them regrowing in the spring. I don’t let this crop get too large, however. Most years it will only grow to maybe five or six inches which is fine. But one warm, wet year the oats grew tall and thick and I just left them. In the spring, the thick crop mulched the ground so well that it stayed frozen well after I was working in the other plots. Because the stalks were dead, bent, and tangled I couldn’t get the scythe through them. I couldn’t rake it off because the stalks were still tenaciously attached to the roots. And because the ground was frozen, I couldn’t dig the roots up! Patience prevailed, and I finally turned it in as best I could when the ground thawed. Now if the oats grow too generously, I cut them down in the fall while they are still green.
PEAS are another good green manure crop. They not only are easy to grow, but add good things to the soil. The farmer’s field peas are rank growing and easily procured in many areas. You can also use your own extra garden pea seed. I often plant a mixture of peas and oats (or other grains) in the spring. They complement each other. The grains crowd out weeds better and the slower growing peas add more leafy material. They are tangly, however, when full grown and hard to cut down with a scythe or to dig in, so it’s best to take care of them when they are about a foot tall.
SUNFLOWERS are not usually thought of as a green manure crop. But if you find yourself with extra old seed it does a good job. Plant it thick; they are good at crowding out other opportunists, maybe weeds you don't want to encourage. If you cut the plants back as they grow they will usually continue to flower, but growing shorter each time until you have foot tall flowering sunflowers in your plot. I’ve found this happens with many flowering plants. Enjoy them, then dig them in for a nice green manure crop.
VETCH: If you buy rye seed in this area, you often can also get it mixed with vetch. Or it may contain vetch seed whether you want it or not. Vetch is an annual or biennial legume and can produce a lot of plant matter. But since it is also a strong grower and can overwinter, I don’t use it in the garden. It can be a good choice for new garden preparation, however, if you are using a tiller to dig the plant material in. It's also beautiful when in flower and I love having some in the fields surrounding the garden.
OLD and EXTRA GARDEN SEEDS can be every bit as good for green manure as the regular crops. When sorting through my garden seeds, I dump all old and extras together. When I have enough, I broadcast it thickly over a resting plot and rake it in. It makes a very interesting and rather fun planting. As the different plants grow at such different rates, I just cut the tall ones down every once in awhile, leaving the patch to grow through the season. Several years ago I ended up harvesting quite a bit of unplanned Chinese cabbage late in the fall that was growing thick and healthy in one of these mixed green manure plots. You can also dig it all in mid-season and plant some buckwheat or oats in the trash.
There are many other possibilities for green manure crops. Try whatever is readily available, see how it grows in your garden, and how it works into your schedule and needs. You will probably want to avoid biennials and perennials, however, particularly if you are digging the plants in by hand. Be sure to cut down all plants before they seed unless you want them to reseed. Most plants are at their peak for green manure just before they flower.
PLANTING THE GREEN MANURE CROP
Green manure seed is generally broadcast rather heavily over the plot, either
by hand or, if a large area, with a hand cranked seeder. You want to plant the
seed close enough together that the plants will crowd out weeds, but far enough
apart that the plants will grow to their fullest. Experience is the best teacher
here. If you are using a mechanical seeder that you are new to, put just a small
amount of seed in and try it out, adjusting the mechanism so you don’t end up
dumping your entire seed supply in the first ten feet. It’s better to go too
sparse the first time around, then go over it again if necessary, since picking
up over-planted seed is probably not high on anyone’s list of things they
As I’ve mentioned, generally you will want to dig your green manure in when
it is about ten or twelve inches tall. If it gets much taller, it is a lot of
work to dig in by hand and it tends to wrap around tiller tines. That doesn’t
mean it can’t be done, however, it may just be a difficult experience and you
will probably resolve to get to it earlier next time. For digging in by hand, it
is sometimes easier if you mow the crop down with a scythe first (or a power
mower), then dig it
in. It is going to look outrageously trashy, but who wants a plain boring neatsy
After all these many years, however, my most common and preferred method for dealing with green manure is to mow it down with the scythe, which can neatly, and quickly take care of one row, one bed, or an entire plot. I then plant into the trash, or just let it lie as mulch. Sometimes the easiest method can be the best. Working WITH is so much better than working AGAINST.
GREEN MANURE is a natural, cheap and easy way to build and maintain the organic matter in your soil. Nature does it all the time, and look how great Her gardens are! May your gardens aspire to such greatness as well.
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© 2002 - 2009 by Susan Robishaw
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