Monday, July 28, 2014

6 reasons to use pine needle mulch in edible gardens

I use pine needles in between my wide rows in the edible gardens.
Here are some of the reasons for using pines needles in wide-row edible gardens. (Read my post "Wide row planting & trench composting" for the details on this planting method.)

Pine needle mulch:
1) does a good job at limiting weeds.
2) doesn't form a crust, so even a light rain filters to the soil and doesn't roll away.
3) is easy to handle and remove when it's time for a crop change.
4) lasts for 2 or more years.
5) does not significantly acidify the soil below.
6) is free if there are pine trees in your neighborhood.

Corn salad, red-stemmed spinach, and garlic growing in wide rows in a winter bed. The pine needle mulch is 4 or 5 inches thick in the trenches between the rows. For crops like onions or garlic I mulch the whole row with about an inch of pine needles—the crop will grow right through it.
Use a very light layer of pine needles over the area where you've planted seeds. Here  I removed the smaller okra seedling and left just one to grow in this space around my okra swales, because you don't want to crowd okra. I always plant 2 or 3 seeds in each spot to make sure I get at least 1 good plant, especially when the seeds are older.
When ready to plant, use a leaf rake to clear the pine needles away. For this garlic, I'm ready to create the wide rows and to dump my kitchen scraps in the bottom of the trench between the rows. Note the wood chips on the path next to the garden.

This batch of needles contained a fair amount of soil after I removed it from the bed, so I raked the whole wad of needles across the lawn to clean them up. As a bonus, the freedom lawn receives an addition of compost.
I collect pine needles from the neighborhood
streets--after a storm is especially fruitful.
Then I keep a pile of them near my gardens.
Down by the lake, a longleaf pine drops its foot-long needles. Easy to rake and great for mulch. My husband mows every other week, so before he mows, I often head down there to collect a new batch.

Why not wood chips?

I've written before about using arborists' woodchips in the landscape, but I don't use them in my edible gardens for two reasons.

Wood chip mulch:
1) is impossible to remove completely once it's laid down. For other uses, like paths and more stable gardens, that's not a problem, but it doesn't work well with all the activity of changing crops at the end of the season.
2) depletes nutrients as it comes in contact with the soil microbes. Again for path mulches, this is an advantage for keeping down weeds, but we work so hard to increase the nutrient level in our edible gardens, why compromise it in any way? Eventually, the chips decompose and add nutrients and humus to the soil, but not at first.

Getting ready for fall...

Yes, it will be 6 weeks or more until I'm ready to start planting the cool weather crops, but there will be some end of summer crops like squashes, cucumbers, sugar snap peas and maybe tomatoes. It was time to turn under my marigold cover crops into their beds, so they'll be ready for the next set of crops. Read about my multi-year marigold experiment: Results: the nematode experiment. 

These two vegetable beds (with their marigold cover crop) are ready to be turned.

There is a Chinese fringe bush at the north end of this bed. Each year I remove its roots that are encroaching into the garden space.
I lay in unfinished compost on top of the marigolds and then
I'll add back the original soil.

First I pull the marigolds and weeds, and then I rake away the pine needles with a leaf rake. I raked the pine needles from this bed across the lawn as shown in a photo above to get rid of the embedded soil. Then I dug out about 5 or 6 inches of soil from the whole bed into the big cart. This bed is about 6.5 ' by 5' and I filled the whole cart. I laid in the marigolds, some grass clippings, topped it with a wheel barrel load of almost finished compost. (Completed or finished compost will not have any recognizable pieces of the original materials. This batch still has some leaf mold and small sticks and chips.)

Then I shoveled the original soil back in place and smoothed it out. I added another half load of compost on top of the soil. Finally, I covered it with pine needles and added wood chips in the walking areas around the bed.

In a few days, I'll turn the next bed.

After burying the marigolds, compost, grass clippings and layering back the original soil, I mulched the whole bed with pine needles. It will sit until fall when it'll be time to start the cool-weather crops. FYI, the downspout shown here, runs into a French drain that runs next to the sidewalk and is released into one of my rain gardens. The rain water then heads down to the lake in an open ravine.

The squash is done, so it was time to turn the marigolds into this bed, too.

I started near the okra (by the bench) and had a load of kitchen scraps ready to compost, so those went into the bottom of this bed for some extra nutrients.

Except for the okra, garlic chives, and the Greek oregano in the foreground, the beds have been turned. The outside bed was turned a couple of weeks ago and so I will probably start planting in that bed first when it's time.

Early in the spring pines also drop their male catkins (sex organs). These break down much more quickly than the pine needles, so if I rake them up, I use them to mulch my blueberries or in the compost pile where their acidity will be neutralized.

For further reading on pine needle mulch:
From Dave's Garden: Pine Needle Acidity: Myth or reality?

Amazing summer clouds just before sunset last week.

I hope you are enjoying the summer clouds and are planning for your fall garden of edibles. Why not purchase my book to help you get started? Organic Methods for Vegetable Gardening in Florida.

Green Gardening Matters,
Ginny Stibolt


  1. Do you think Australian Pine needles would work as well? I have more of them than I have if Slash Pine.

    1. No, don't use them, because they are allelopathic and exude herbicidal chemicals that kill nearby plants, which is why you rarely see anything growing under them. Secondly, they are on the Category I list for being invasive in Florida and their cones will sprout many seedlings, which causes more problems than it solves in your garden. In addition, Australian pines are pines, but flowering trees. Read my post on these plants:

    2. I meant they are NOT pines, but are flowering plants, or angiosperms. Pines are gymnosperms.

  2. Awesome! I just purchased your book on Amazon. I am excited to read it! Thanks!

  3. Would Norfolk Pine litter work?

    1. Possibly, if it hangs together and doesn't decompose too quickly.

  4. Aren't needles in gutter full of salt in northern states?

  5. Will placing pine needles on a pine stump help it rot faster?