How do we reap when our beds are turning?
June 14, 2010 12:05 PM   Subscribe

Questions about soil preparation and space planning for garden beds

My wife and I are in the process of planning a couple of large garden beds. We live in Central Florida on about 1/4 acre of land.

We will be renting a rototiller to create two 6' x 30' (raised, mounded but not bordered) beds from what is currently a patchy lawn of bahia grass with a lot of weeds. The yard is free of cinch bugs and other pests, and our other plants (banana, citrus, jasmine, bird of paradise, passion vine, and calladium, among others) are growing very well. As with most of Central Florida, the soil primarily consists of sand. A home test kit shows: pH 6.0, N very high, P low, K medium. I've lived in this house for 12 years and am the second owner. The house was built in 1981 and AFAIK the area was never used for anything other than a lawn since the house went up.

The garden will be used to grow herbs and vegetables - mostly culinary, but also some others such as medicinal herbs. Most of the vegetables we're putting in at first are "above-ground harvest" types, although I imagine that we'll eventually be growing a lot of root vegetables as well.

Separate areas of the yard will be used in the future for keeping a few chickens and for planting a small orchard of fruit trees.

We would like to avoid using chemical fertilizers if possible, but they're not out of the question. Instead, we'd like to supplement the soil with free compost from the local landfill and store-bought manure; these help the drainage capabilities of the soil as well as (hopefully) restoring the chemical balance.

We'll be making extensive use of soaker hoses, since the Orange County watering restrictions of two days a week are not applicable to drip or soaker systems.

As far as future maintenance of the soil: the beds will probably be turned in small sections after each area is harvested and cleared, since with our long growing season they will rarely be completely empty. I'm planning on rotating with legumes to keep nitrogen levels high, and adding lots of compost (hopefully produced onsite after the initial planting) to the soil as needed.

We plan on using high-intensity gardening techniques, thinning the plants to a smaller recommended spacing and in staggered rows. We will also be using companion planting (interplanting), including the use of marigolds and other plants for pest control.

Considering the timing, this year we are just going to put our starts in the ground and see what survives. Later on we will pay a bit more attention to the calendar as far as planting and harvest dates are concerned.

My questions:

1. How much compost and manure should we use to prepare the beds?

2. When using marigolds, borage, bee balm, etc. for pest control and attracting beneficial insects, what is the "effective range" of one plant? Do we need to border the space with them, or would a plant every few feet throughout the garden be adequate?

I've included a lot more detail than needed to answer these questions in hopes that other advice will come to light - any would be appreciated.

Thank you, MeFites, for any help you can offer. I worked a similar garden in the Pacific Northwest years ago, but my first wife was the one who had the expertise.
posted by tkolstee to Home & Garden (10 answers total) 5 users marked this as a favorite
Call your Cooperative Extension Office. They have a wealth of information.
posted by theora55 at 12:13 PM on June 14, 2010

I garden in containers, and I find that the anti-pest plants do not have a wide range, it is usually limited to the container in which they reside. I had lettuce literally right next to a sage plant (separate pots) and aphids got my lettuce.

In addition to the Extension Office, you might check local garden centers (i.e. not corporate garden departments in larger home improvement warehouse stores). They may offer classes, but if nothing else, the staff in places like that are often quite knowledgable.

Good luck, and happy planting!
posted by hungrybruno at 12:29 PM on June 14, 2010

Instead of rototilling down, have you considered lasagna gardening? I established my raised beds this way two years ago (although mine borders constructed of untreated 2 x 4s) and it's been very effective at keeping out the weeds below (the only exception is quackgrass, but I think quackgrass is hardy enough to survive the sun exploding, so I have to live with pulling it out as best as I can). This way, you're building up and you can just get some perfectly blended garden mix soil delivered to fill up your beds.

If you buy the manure in bags, they usually say how much to put in a given area (I use one bag for a 2m by 1.25 m bed). If you have an alternate source, you can still look at a bag in a garden centre for a rough idea. I think you'd have to really overdo it to have a problem, though.

Best of luck! (I'm so jealous that you can have a banana in your yarden!)
posted by Kurichina at 12:46 PM on June 14, 2010 [1 favorite]

Oh, since my link isn't specific, I should add that when establishing the garden, I used a fairly thick layer of newspapers and cardboard as the first layer of the 'lasagna' to really ensure that the weeds below couldn't get through. (Except the bane of my gardening existence, quackgrass... sun exploding... yadda, yadda, yadda.)
posted by Kurichina at 12:49 PM on June 14, 2010

Because FL soil is so sandy (I live in Seminole County), I also recommend laying down cardboard or newspaper and building up with a mix of compost and topsoil. From what I've read, the decomposition of the paper layer coupled with the nutrients filtering down from above increases the fertility of the original soil beneath. This way, you don't have to add artificial fertilizers.

We're doing this right now as well. MeMailing you.
posted by cereselle at 2:31 PM on June 14, 2010

I HIGHLY recommend lasagna gardening given your sandy soil and possible water restrictions. You want to get as much organic material into your beds as possible to retain water. If you can get free compost awesome, use as much as possible but really any organic material you add is a bonus and will break down quickly in your heat.

Mine are similar to kurichina's in that i used untreated 2x4s over a thick layer of newspaper and cardboard but instead of buying soil and compost I just filled em with straw bales. Plant directly in the straw bales and add more organic material/ dirt/ compost as you need/ acquire it. The straw breaks down over the winter and the next year you can add more straw bales or just plant in the substrate if you have enough by now. I never turn my beds over, I just dig the existing stuff in and mulch it and plant again in the spring. Works great and is much cheaper than buying dirt! Tomatoes in particular grow well in strawbales.

The exceptions are plants that like sandy soil like carrots and some Mediterranean herbs, these you can plant in the sandy soil and they will be very happy there. Raised beds are good for 3 things 1) quickly making soil better 2) improved drainage and 3) heating the soil. If specific things don't need any of those then you don't need a raised bed for those crops.
posted by fshgrl at 2:38 PM on June 14, 2010

And though I have not gardened in Florida, the obvious thing to do for low phosphorus is apply bone meal. I throw some in the planting hole as well as top dressing. If you have dogs, they may try to lick it off the ground, though.
posted by Listener at 3:19 PM on June 14, 2010

I would recommend Steve Solomans book, Gardening in Hard Times for a good overview of doing a natural self sustaining garden plot. I would also try to get a more thorough soil test done to make sure you don't have some other toxic stuff there like lead or such

First I would Use roundup to kill your grass and weeds, then rototill. Roundup is not persistent, and will not cause any long term toxicity if you don't overdo it. It iwll save you lots of time and effort in weeding however. Your compost needs are mostly for organic matter, this wil help turn your sandy soil into something that will hold water better. You will need to fertilize for P. . Salomans book has a great fertilizer mix of 4 parts seed hull (he used cotton seed but any will do) one part dolomite line and one part Calcium lime and then one part kelp meal but any kind of blood meal would do and this will provide the P. Crop rotation is the key to keeping the pest down and there really is no substitute for mechanical weeding unless you want to use a roundup ready seed and that isn't really practical for a home garden. I would use some variant of the three field rotation-one fallow, and if you can't get something to come in a graze for a few days that would be perfect-like goats or sheep or even chicken. One would be in legumes-peas, beans and such, and one in high intensity vegetables/grains/tubers. Then switch the fields every year. This will keep the soil borne pests under control, and nothing will keep the air borne pests away except for pesticides, the best defense here is strong plants and good luck. Being isolated from large scale agriculture helps a lot too as bugs don't travel far and your little plot would support a large population on its own. As you get better at it (and it takes years to develop the skills) you can provide a lot of your food easily off of 1/4 acre-at least for vegetable needs, maybe all since you can grow two crops a year in florida most years. Good luck.
posted by bartonlong at 4:52 PM on June 14, 2010

6 foot wide garden beds are to wide to harvest all you vegetables without stepping up into them. Walking on soil compresses it, so I recommend 4 feet at the widest. You want to be able to reach into the center of the bed without standing in it. You will also want to decide if 30 feet of continuous bed makes sense. Will it be a pain to walk all the way around pushing a wheelbarrow or dragging a bag of amendment? do you have enough water delivery (GPM) for the irrigation of a 30 foot bed without making it impossible to do laundry or take a shower? Lay it out with a hose or some rocks and make sure that size bed makes sense.

1. How much compost and manure should we use to prepare the beds?

Well, it's really impossible to answer this question for two reasons: it depends on the compost and manure you're talking about ( for example: chicken manure? steer manure? both have different nutrition profiles, and steer manure is absolutely not recommended because it often comes from feedlots, and is therefore full of salt); and more importantly, it depends on the texture and nutritional profile of your soil as determined by a professional soil analysis. Home test kits are too vague, use too small a sample size, and are often wrong. A proper soil analysis from a lab will tell you exactly what amendments you'll need and in what quantity. It will also tell you what form of nitrogen is in your soil: NO3 will quickly leach through your sand once you start watering, NH4 does not usually leach. If your test kit is picking up organic nitrogen, N2 (urea), that is not actually available to plants without being mineralized by nitrifying bacteria.

It is likely that commercial compost and manure is not going to provide enough nutrition for multiple crops no matter what kind you get, especially because you have sandy soil. This problem is increased exponentially by adding things like straw or worse, cardboard to your soil. Cardboard has an extremely high C:N (carbon to nitrogen) ratio, and that means that the microorganisms that break it down must take nitrogen out of the soil to do so.

You'll want to utilize green manures to help replace nitrogen between crops because you will need to add organic matter to the soil. You can also plant perennial nitrogen fixing plants, and intersperse beans and peas throughout the garden. Cut them off and leave the roots in the soil when they're done.

RE: restoring chemical balance- if your pH is as low as the test says (again, you should get a proper test as these are often wrong), adding a lot of organic matter will make it even lower. If you were my client, and you didn't do a soil analysis, I would advise you to go to your local rockery and get a bulk delivery of good garden soil and mix that into the existing soil, along with good compost and some rock phosphate (much less ground water polluting source of phosphorous than manure). And then I before planted any vegetables, I would plant nitrogen fixing cover crops, compost the tops when they mature, and till in the roots. Then spread the compost on the beds. Yeah, you won't have vegetables this summer, but you'll have better soil.

Chickens will be a great addition, too.
posted by oneirodynia at 6:29 PM on June 14, 2010

Horse manure is a tremendously effective fertilizer, and you can often get it for free from local stables (just check the yellow pages). They pick it out of their stalls and pile it up, then often pay someone to take it away or spread it on their pastures; having someone come collect part of it can save them time or money.

You'll probably have to compost it yourself, though. This isn't difficult, just takes time.

I give horse manure away; we either load it into people's pickup truck beds or we shovel it into leftover feed bags so they can take it home in a car.
posted by galadriel at 7:09 AM on June 15, 2010

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