Garden Soil Integrity

Asked April 21, 2016, 11:21 AM EDT

Hi there. I'm a gardening novice and am hoping you may be able to answer to my questions or can point me in a good direction for answers. I apologize in advance for the lengthy detail to include my backstory but I hope it helps to understand my many questions. I am inquiring about the importance of soil quality used for vegetable gardens maintained in containers. Does the soil need to be the same throughout the container, and does the soil at the bottom of the container affect the quality of the vegetable growth/health even if the root system doesn't reach that far down? Also, can the material of container affect the growing conditions? My questions stem from concern over the soil and material we are using in our home garden. Last year my husband and I attempted our first container vegetable garden on our deck with varying seeds and lots of only high quality organic soil. We used barrels, ceramic pots and wooden crates for containers. The large barrels/pots were very successful with beautiful healthy vegetables (kale, basil, mint, rosemary, oregano, green onion, thyme, tomato, wild flowers) but all of the smaller pots and wooden crates barely produced anything more than slow growing seedlings which halted growth and were followed by a rash of mushrooms. I assumed then that the problem with the crates was that they were made of recycled wooden wine crates and that the integrity of the crates may have compromised the soil conditions because I noticed what appear as black mold growing in the wood; though my husband argues that the dis-colorization in the wood wasn’t necessarily mold and that regardless it wouldn't affect the soil or growth/health of the plants and the mushrooms have no influence. However, because the smaller pots didn't produce any productive growth, my husband started throwing his cigarette butts in these crates. (I personally do not smoke cigarettes and place high importance in the quality of my health and environment leaning toward organic-living hence my concern.) These crates remained on our deck during the off-season because my husband wanted to recycle materials for the next growing season though I was hesitant. The next growing season has now arrived. We purchased more large barrels and reused the containers that supported successful growth last year. However, my husband has already recycled the soil from the crates and pots that were unproductive. Using this recycled soil with the cigarette butts removed, he filled the bottom of all of our barrels and pots (no crates this time around) and then topped them with new bags of high quality organic garden soil. My husband insists that the soil at the bottom as no effect on the growth or growing conditions because the root systems don’t reach that far down. Should I be concerned? Would the vegetables/herbs absorb any toxins from the bottom soil because of the cigarette butts that were previously discarded there? Would the rash of mushrooms from before have dormant spores remaining that would compromise the growing conditions? Would the “black mold” from the previous season’s crates be absorbed into the soil and also compromise the growing conditions? Is it safe to eat food grown from such conditions? Thank you for any feedback you can provide.

Prince William County Virginia

2 Responses

Starting at the top with your first questions:
The soil should be consistent, more or less. It should be easy to mix the old and new together. Doesn't have to be exactly the same, but you don't want to have poorly draining soil on the bottom so that water drains down to it and then backs up, saturating the upper soil for long periods. This could drown plant roots. So, yes, bottom soil can affect what happens above it, drainage-wise, even if the roots don't extend down that far.

From your description, it does not sound like your old soil has any particular disease. It's possible that the amount of watering you did was not successful in all containers because they were not the same. Size changes watering requirements. Also, the material the container is made out of affects watering, because some don't allow evaporation through their sides and other materials and even absorb moisture.

If the wooden containers or the small (plastic?) containers retained moisture longer (stayed soggy), the plants may have drown or died of root disease. The mushrooms, mold and mildew you described suggest this. Soil needs to drain well in containers. Plants like soil about as moist as a wrung-out sponge. Do not water on a strict schedule. Water as needed.

The cigarettes should have no effect. Yes, any food grown in the soil should be fine.

Please read through our Grow It Eat It section's info on container gardening. It should be very helpful:

And, lastly, here is our pub on container gardening:


Thank you for your quick reply. You have eased my worries. I do think the issue with the crates may have very well been due to poor drainage as you suggest. And, we did water the plants fairly evenly regardless of container type so that more than likely played a role as well. I will be incorporating your watering suggestions this type around. Thanks again!