antx227
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PLEASE HELP!! Mold growing on my lettuce roots!

Hello everyone! I am new to this forum as well as a newbie gardener. I built a garden box 20' x 6' recently and filled the bottom layer with some fill dirt I picked up from Craigslist which was very dense with a lot of clay material. The top I filled with some soil I picked up from Home Depot.

I had spread some lettuce seeds awhile back and everything was fine. Lettuce was growing great and was able harvest some of them until they started withering away 1 by 1. I decided to remove the lettuce and plant new seeds and when I pulled them out there were greyish white mold growing on the roots. Every root I pulled up had the mold on there. Is this what is causing my lettuce to die and if so how do I fix the problem? Any help would be great... I tried googling it, but couldn't find the right answer. Maybe a drainage problem? Please help... I just planted new seeds, but I'm thinking it'll happen to them too. I light water daily and the weather here is at about 60 degrees with minimal sunlight. Thanks in advance!

[img]https://i96.photobucket.com/albums/l200/antx227/IMG_0413.jpg[/img]
Last edited by antx227 on Tue Sep 04, 2012 1:59 pm, edited 2 times in total.

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rainbowgardener
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Instructions for posting pictures are in New to Helpful Gardener under Helpful Tips and Suggestions for New Members.

Definitely sounds like a drainage problem. The "fill dirt" was probably nasty stuff dug out of the bottom of a construction site. The stuff from HD depends on what it was. What they sell as topsoil is generally not very good and is often labelled as not for use in garden beds.

It will be a lot of work, but if you want to be successful, I would dig everything out of the box. Get rid of as much of the "fill dirt" as you can. Mix the rest in with some amendments: compost, composted manure, potting soil, peat moss, vermiculite, greensand, etc. Whatever you can come by. I would try to end up with the HD stuff not much more than half the volume of what you put back in.

Good gardening depends on good soil! Start a compost pile so that after this you will have your own homemade compost.
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antx227
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Thanks for your reply! I just uploaded the picture showing the mold... Sure does seem like a lot of work since my garden bed is big. Sucks I just planted new seeds about a week ago and it is already coming up. Maybe I'll wait for the seeds to be big enough so that I can still keep them after changing out the dirt. I knew that fill dirt was not a good idea :(

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applestar
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Ah ha! I'm seeing the photo you posted -- what you have is not really soil but more like incompletely decomposed mulch. Lots of woody organic matter -- which explains why the lettuce is suffering.

The mold-like growth is not "mold" as such but more likely fungal mycelia (roots for want of better word) growingon and helping to decompose the wood and enjoying the lettuce root exudate -- not the lettuce roots themselves.

While the stuff is still breaking down, this sort of matter will tend to tie up the nitrogen. There might still be drainage issues going on from the lower layer fill dirt as well.

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jal_ut
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I would not get rid of that soil. I would mix it all well the fill dirt with the other stuff. Take a fork and turn it over. I think it just needs time for the organic mater in it to decompose better. Try planting something else instead of lettuce. Also instead of watering every day, water once a week deeply, or if your plants wilt water then, whether it be 4 days or a week. Clay in soil is not a bad thing. About 20 % clay is a good thing. It actually holds water well and has lots of minerals in it that the plants need. It will be good if you can mix the organic matter in the other type of soil with the clay layer. I also wonder what is under the bed. Is it your local soil and what type soil is that? Did you use a barrier? It is probably best to not use barriers under raised beds and let the roots go deep if they can into the underlying layers. Yes, most varieties of plants we grow in our gardens will send roots quite deep. Three feet and beyond. They can find water and minerals in those lower layers.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-

antx227
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Thanks for the advise! The clay fill dirt below is very dense and tends to crack and harden when watered. I have about 5 inches of the top soil I bought from HD and about 6 inches of the clay dirt below then its cement. How long does it take before the soil decomposes so it'll be good? The person at HD told me to get that one for my lettuce... argghh!

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jal_ut
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Yes, drainage is a problem if your bed is on concrete and the bottom layer is clay. This bed would benefit from 2 to 4 inches of sand added and worked in. If you can get some sand and organic matter worked into the clay, things will be much better.

applestar is sure right, that stuff is not even a good imitation of soil. It is much too coarse for the roots to get good root to soil contact. Lettuce would do better in the clay in that regard.

Natural loam soils consist of clay, silt, sand, water, air, organic matter, and a host of micro-organisms.

The things found in fake soils like perlite, peat moss, and vermiculite, are pretty much useless as far as nutrient value. They can only act as root anchors, but mostly they are too coarse for good root to soil contact. Too much air in the soil dries out the roots too fast. Manure and compost are good soil amendments, but by themselves are not good growing mediums. Too Hot! Start with the things I mentioned in my list of natural soils and add some compost then you will have something that will treat your plants well.

Wood chips, and or shavings are organic, but as mentioned suck up the nitrogen as they decompose. They are also slow to decompose due to their relative density.

Greensand has some minerals in it and can also help to break up the clay.

Do you know a bricklayer? Ask him if you can get some sand. They usually have a truck full of sand dumped on a job, and generally leave a lot behind when they are done.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-

antx227
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https://www.homedepot.com/h_d1/N-5yc1v/R-100427391/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=soil&storeId=10051#.UEgmVCLxXM8

This is what I bought from Home Depot thinking it was regular top soil. I should of went online and read the reviews before making this mistake. I wish I never planted my seeds already... I guess you do learn from your mistakes. You think its a better idea to remove everything and start fresh or should I mix some perlite and fertilizer in there? Thanks!

antx227
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https://www.homedepot.com/h_d1/N-5yc1v/R-100355793/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=soil&storeId=10051#specifications

Will mixing this help as well with the soil I have now? Thanks for all the advise... You have been of great help to a newbie!

cynthia_h
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I'm not well-versed on independent nurseries on the Peninsula, but [url=https://www.sloatgardens.com/locations_and_hours/gardencenter.htm]Sloat Garden Centers[/url] have a good reputation Bay Area-wide. The one closest to you is in the Sunset, at Sloat Blvd and 46th Avenue (practically on the beach).

I recommend taking these photos to Sloat and telling them what you've told us. Show them the situation and ask them what they advise. Be aware that their recommendations may be pricey, and please don't feel pressured to follow through with everything they suggest. Do take notes, though, so that you can perhaps get some of the supplies from them now and seek out some of the supplies later, after the "blitz" of being a new gardener subsides. :) Yes, there's definitely an information overload (aka "learning curve") involved in any new endeavor, and gardening is no exception.

If you can swing it, I'm sure Sloat will have lettuce and other fall-planting veggie seedlings, so you won't have lost too much time with this setback. In the meantime, if you find a good, independent nursery closer to Daly City, please let us know about it here on the forum! There are several active members from the Bay Area, and who knows how many readers who never post would also like to know?

Best wishes! :)

Cynthia H.
Sunset Zone 17, USDA Zone 9

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applestar
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Yes, definitely find a good independent garden center ASAP. :D

Listen to jal_ut though. The mulch-like material you used in and of itself is not a good soil, but mixed with the clay fill dirt, it will provide channels for drainage while they still have their shape, keep the clay from clumping together, and provide good humus after they break down.

Coarse sand mixed with the clay and organic matter will complete the desirable soil composition. I usually get things like sand and paver underlayment sand from big box stores, but I look for GOOD premium soil mixes, potting soil, compost, and better soil amendments from independent garden centers.

You asked about Miracle Grow brand soil -- I prefer to grow organically, so I usualy add compost, rock phosphate and greensand (I kind of feel greensand is geologically local to the east and gulf coast and west coast gardener's might be better served with azomite or ground volcanic rock -- just IMHO though :wink:). Kelp meal is another good addition. I might add composted manure when growing nitrogen-hungry crops like corn or pumpkins, but I'm more likely to add alfalfa or grow legumes in the previous rotation for other crops like tomatoes.

I read the reviews For the first "not-soi"l product, and thought it's funny how people panic over mushrooms, but it's actually a good thing. (those white mycelia you discovered will most likely eventually produce mushrooms which are basically "fruits" -- so don't be surprised). But they help the woody material break down quicker and make fertilizer in the process. It means the organic matter is ALIVE with good soil micro-organisms. The act of mixing into the subsoil will break up the mycelia and feed the soil organisms, but they will continue to do their job. I use mushroom compost and premium soil mixes with ADDED mycorrhiza for the same benefits.

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applestar
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Oh! I know what struck me -- you said its CONCRETE underneath. Make sure the side supports for the garden box has gaps along the sides for good drainage, especially along where it meets the concrete. Was the concrete pad designed to slope at all or is was it leveled flat?

5"+6"=11" ... Is that the depth/height of your garden box or can the soil depth be made deeper? I think this would limit what you can grow here....

ETA -- I just reread your posts and you said "cement" and in your OP you said the box is 20 FEET by 6 FEET. 20 ft? Having a hard time trying to picture the setup. :?

But if it is solid bottom and not earth underneath, then the soil mix needs to be lightened to container soil mix consistency -- a ratio involving definitely less clay, more humus and porous soil conditioners. If you don't have the additional height to add, then yes, some of the clay soil need to be removed like rainbowgardener said.

antx227
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[img]https://i96.photobucket.com/albums/l200/antx227/photo.jpg[/img]

Thanks so much for your responses... Learn something new everyday!

This is a picture of my garden bed from when I first started...

The bed is 20 feet and the bottom is cement... it is sloped down slightly which helps a lot for the drainage. I'm going to pass on the Miracle Grow because I do want to keep my vegetables organic. I do not have much room to play with depth wise so I'm going to start fresh and dig out some of the clay fill dirt. So pretty much all I need to buy now is the sand correct? Mix it with the clay and the mulch like soil I have now... I just want to make sure I put the right amount of sand, clay and the mulch. You guys have been great thanks!

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applestar
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Since fill dirt/subsoil is nutrient-poor and sand is basically silica (no nutrients), I think also adding some organic potting soil or maybe container soil would be a good idea. (I like Dr. Earth or Gardener's Gold, but I think there are a couple of other premium brands that are regionally available to you -- mmm. Fox Farm or something and one other that I can't remember ... Black something?). This will also help to lighten the soil mix to prevent compacting like we talked about.

(Note that if the raised boxes were directly on top of the earth, I would recommend good quality top soil instead)

After that, additional amendments/nutrients will depend on what you plan to grow or you can just get a box or bag of organic vegetable (leafy) or tomato (fruits) fertilizer and use according to directions.

antx227
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Thank Applestar! You've been of great help... Looks like I got a big project coming up in the next few days!

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