Worm Castings for your Roses

Most of this was taken from our Rose Club Newsletter, and then I added a bit:

At the recent Cabin Fever meeting, a question/answer forum was set for the Friday after each speaker’s talk. A question was posed to me regarding the use of worm castings in rose beds.

I haven’t done that, depending on those critters that live IN my rose beds, but a friend of mine has a business with red worm castings. He and his wife have moved to Oklahoma, but he did give me some advice I wanted to pass along.

He said there are three ways to use castings:

  1. put some in the hole when planting;
  2. top dress by scattering over the soil in the rose bed and scratching it in; and
  3. most interesting for roses, Jack Chambers, Sonoma Valley Worm Farm, says if you make a compost tea with castings and spray the roses it acts as a foliar feed and prevents blackspot. “He has beautiful, huge roses.”
  4. Note: Warm castings have a pH range of 7 to 8, roses prefer about 6 to 6.5. Mix the castings with compost or just the normal soil and you’ll be fine and the roses will love it.


  • Natural Worm Fertilizer – There is no better natural, organic nutrient you can use than worm fertilizer.  You can sprinkle it around plants, or dig some into the soil around a plant.  You can also use a spreader for a larger scale application.  Don’t worry about exact amounts.. as you cannot hurt your plants by using too much.  Great when transplanting.
  • Germination – Mix up sand with around 20-30% of earthworm castings for increased germination of seeds.  Once germinated the plants will be have enough nutrients from worm castings to grow for around three months. (source)

For the compost tea, in a 5-gallon bucket of water add a cup or two of castings tied up in cheesecloth and a tablespoon of dried molasses (to feed the microbes). Put in an air pump (you can get it at Walmart in the fish department). Let it run for 24 hours, and use quickly as the microbes will start to die.

There is a business in Otis Orchards that sells worm castings for any of you who would like to try this, particularly another questioner who asked if there was an organic method for getting rid of blackspot. It’s Marle Worm Growers.

How do you get the worm castings?

You can buy them from Amazon, of the link above or google “worm castings.” Or you can use the article on that at Gardening Know How or at Pennington.

Here’s a warm casting harvest. This set up looks much like the one that I use.

Here’s a video, about 7 minutes, which goes into some more detail:

You can find lots more on YouTube. Just search there for worm castings or worm bin.