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kristimama

Planting in sandy loam vs. all compost?

kristimama
15 years ago

OK, so here's another question for y'all. :-)

I'm building raised beds because I don't want to grow directly in my native soil. I'm bringing in about 6 cu yards later this week... I can make it 100% compost, or a richly amended sany loam that's certified organic for veggies.... now I just need to understand the best choice for me.

I'm wondering if you could share some of the merits, pros or cons of growing in sandy loam vs direct into compost?

I was thinking the sandy loam would have better water retention ability, but the compost might stay more fluffy.

I know Mel/SFG basically advocates a mix with compost and vermiculite, I have read and experimented with SFG in raised planter boxes. But I am also attracted to the "french intensive" approach which uses actual soil, too... and I have heard that there are just some plants that do better when they're planted in actual "soil." (i.e. sandy loam).

Any of you more seasoned gardeners willing to share what you all do?

Thanks!

-k

Comments (9)

  • dchall_san_antonio
    15 years ago

    If you keep mulch on top of the loam, it should remain fluffy. It is the soil fungi that make soil fluffy. Mulch provides a relatively stable, moist, and cool environment for them.

  • gardengal48 (PNW Z8/9)
    15 years ago

    Because virtually any compost you will find is not completely finished, it will continue to shrink and if you use it alone, you will find the level in your beds much lower at the end of the season. Generally, a sandy loam is going to offer better drainage as well as a mineral component that is lacking in pure compost. Ideally, I'd go for a 2 or 3:1 mix of loam to compost. If they are coming from the same source, can you have them combine the products? Say 4 yards of loam and 2 of compost?

  • kristimama
    Original Author
    15 years ago

    Thanks Gardengal, that's the kind of info I'm looking for. Actually, the product I'm buying is already a mixed with composts and sandy loam... don't know the % but I know that it's at least 15% chicken manures and 15% plant based composts, plus fir fines, composted rice hulls, and composted grape materials from the wineries. (I'm in the SF Bay Area). It's pretty darn rich, just a little heavier (obviously) than a straight compost.

    And for the amount I would need about 6 cubic yards, there's NO WAY I'm going to be hand mixing anything. LOL. And the thought of hand assembling 5 different kinds of compost and hand mixing (a la Mel's Mix) seems completely unnecessary for me when this other mix is around. Even though I general subscribe to other "intensive/SFG" principles.

  • adirondackgardener
    15 years ago

    Compost is not soil. Soil is a more complete growing medium that contains many trace elements your plants benefit from. As gardengal mentions, compost will continue to decompose so a yard of compost that you paid good money for may be a couple of cubic feet in time. Not through the fault of the seller, but the microbes. The ultimate purpose of compost is to become humus in the soil.

    Compost is also pretty poor at anchoring larger plants, corn for example.

    I practice the French-Intensive & Bio-Intensive methods in mounded raised beds so I have a natural aversion to any of the Square Foot guy's expensive mixes. If there is a reason you can't plant in your native soil (and it seems like anytime I ask the reason a few people here throw hissy-fits,) I'd suggest that you buy soil that will last, that you can plant in now and enrich over the years.

    Soil is your garden's greatest asset. Compost is ephemeral.

    Wayne

  • kristimama
    Original Author
    15 years ago

    Thanks, Wayne. I got my feet wet with SFG last spring (some planter boxes on a concrete patio) but I am starting to lean towards a more French intensive or bio intensive approach, even though I don't yet have my own compost bin.

    No hissy fit here... I just have some serious concerns about my native soil... the original 30+ year owner of our house was a jeweler and I have some concerns about what might be tossed into the site that we're going to use as our garden. Also, we did some construction last year (demo of old lead covered house and compaction of our clay soils), not to mention a major gopher problem. All of which made me want to plant essentially a 24" deep box above ground with a rodent mesh underneath. (I actually posted this question, too.) The SFGers think anything more than 6" is a waste, but I know I need more. I was almost completely convinced that 16" would be fine but I am thinking of going back to my original plan of 23" deep boxes. Plenty of room for my veggies without rodents snacking on roots. LOL

    Anyway, I appreciate your feedback. My intuition is that the loam/organic mix I'm getting (it's about 30% loam and 70% organic matter) is going to be great.

    -k

  • gardengal48 (PNW Z8/9)
    15 years ago

    I agree ;-) Based on your description, your sandy loam sounds just about ideal. It would be comparable to what's commonly called 3-way mix here - a combination of loam, compost and sand (usually.....sometimes this is replaced by other ingredients). This is perfect for raised beds.

  • Kimmsr
    15 years ago

    People plant and grow "stuff" in Lasagna beds which are all organic matter all the time with no problems, according to them. There is no reason what you want to do would not work.

  • vivekparekh_hotmail_com
    14 years ago

    Hi kristimama,

    Can you tell me where to bought the soil from?

  • organicislandfarmer
    14 years ago

    I have to say, right or wrong its working for me so far. I dug up a bunch of sand from my yard,(I live near the beach) and I mixed it by eyeball with purchased topsoil, cow manure, vermiculite (ala SFG) and moss. I have a really sandy mixture that stays loose but also retains moisture while allowing excess to drain off. You can look at me photos on facebook the plants are only 2 months in the ground. I think they are doing great. I plant in containers only because its a house I rent and the owners wont let me plow the back yard!lol. The dirt you plant in is so important, also the fertilizer you use, the composting, rain barrelling etc. I chose deeper containers for plants that need to grow up tall and I chose shallower containers for my squatty plants and vines. Unless you are planting root vegetables or the tall plants I wouldn't sweat the thickness part mostly because its unnecessary extra. I did do deeper soil for my radishes, beets and carrots other wise the carrots grow crooked when they hit bottom.lol.

    Here is a link that might be useful: robs urban farm