Shop Products
Houzz Logo Print
ralphw_gw

Pine Bark Effects On Seed Germination

17 years ago

I am about to start planting seeds inside for all sorts of flowers and vegetables, and I am concerned about whether pine bark in the planting mix will inhibit germination of some of the seeds. I grow a lot of plants in pots and recently have been using a mixture of mostly aged, ground pine bark (sold as soil conditioner) plus a small amount of composted manure from Lowe's, which is mostly sand. I add a little lime to counter the acidity of the bark, and in the summer add a little Epomea plant food. This mixture provides fast drainage which is an advantage during the winter and works well for starting cuttings, potting up small seedlings, etc., but I am concerned about whether I can use it for seed germination. Last fall I attended a lecture on Blueberries at J C Raulston by Dr. Ballington during which he strongly recommended mulching Rabbiteye Blueberries with pine bark because it has a low pH and because it is thought to have allelopathic properties that inhibit weed seeds from germinating. I have noticed that one of the major commercial potting soil companies, Fafard, has aged pine bark in all of their Southern mixes except for the seed starter which is 50/50 peat moss and vermiculite. I also have been incorporating ground pine bark into the top layer of soil in the raised beds that are now growing transplants of lettuce and other cool weather crops, but that may be direct seeded with crops like corn, beans and okra later. Of course if pine bark controls weeds well enough, it might be worth the effort to start more things from seed inside and transplant them into the garden as recommended by the author of Square Foot Gardening.

Comments (9)

  • 17 years ago

    Hi Ralph! I don't know the answer to your question but I often make similar potting mixes with the ground bark so I will be very interested in any info you find. I have wintersowed the past couple of years but have only used commercial potting mixes or seed starting mixes. The more peat they contain the harder they are to deal with moisture issues in the containers but I believe germination was better than with the heavier mixes I have used.

    Have you posted this in the Growing from Seed and Wintersowing forums?

  • 17 years ago

    I thought the reason we use pine bark fines was because it took so long to break down - thereby not offering much of anything to the soil, roots or seedlings growing in it.

    I can't imagine pine bark being more acidifying to soil than peat moss.

    I use a pine bark home blend soil mix for cuttings and divisions and for large seeds. I use a peat based soiless mix for small seeds (mostly because I want it sterile).

    The only secret I have for seed sowing is to use rain water to water them until they are ready to transplant.

  • 17 years ago

    Pine STRAW is known to have allelopathic pre-emergent qualities on some seeds. Have not heard of nor seen reports of AGED pine bark doing so, though fresh product may. The aged PB loses those properties, but pine straw does not.

    PB retains quite a low pH, even after being aged, but not (typically) as low as sphagnum peat. Most commercial potting mediums are pH adjusted.

    I am a big fan of the Fafard commercial mixes, and have used them (with aged pine bark) for germinating purposes for many years. I also make my own container mix using pine bark (and perlite and Turface MVP) and very little, if any peat.

  • 17 years ago

    rhizo 1, which Fafard mix would you recommend for wintersowing? I need to get started and haven't bought anything yet. The Fafard potting mixes I have used for container growing were almost all bark fines.

  • 17 years ago

    Speaking of Fafard, they have a large soil mix plant just off Hwy 29 a mile or two north of Anderson, SC. The last time I was there you could pick up large bags of potting soil for $6 or 6 bags for $30. These are returns (or reruns) and are mostly labeled Custom Mix, but they usually are similar to their 3M formulation which is their most popular blend. If you want Seed Starter or a specific blend, it doesn't hurt to ask.

    Here is a link that might be useful: Fafard Potting Soils

  • 17 years ago

    Take a look at this one. It's fine textured enough to be suitable for all seeds, but coarse enough so that you don't have to worry about damping off, algae, and other pain in the neck issues with the usual potting mediums.

    For very tiny seeds, sow them on top and then apply a dusting of sphagnum peat on top, then water gently.

    I've used this Fafard as a base for other container projects, too, by adding more perlite, bark fines, and/or Turface MVP.

    This product might be coarser than some people are used to for seed germination, but I've had nothing but success with it. The 'light weight' Fafard mixes have wetting agents and fertilizers in them, which I (personally) hate to use.

    Here is a link that might be useful: Good for sowing

  • 17 years ago

    Thanks, I'll ask my local nursery if they can get it for me.

  • 17 years ago

    Hi,
    Does anyone know where I can purchase Fafard potting soil in the Chapel Hill/Durham NC area?

    Thanks

  • 17 years ago

    Iris, you can find a list of retailers for Fafard products by clicking on their web site. Fafard lists "Potted Products" in Chapel Hill, "Orange Garden" in Hillsborough and "For Gardens Sake" & "Stone Bros and Byrd" in Durham.

    Here is a link that might be useful: Fafard Potting Soils