questions about soil and fertilizer

[rafiwinters]

Hi all, just joined (rejoined?) the group. Seeking thoughts or advice. There's a raised garden bed at the back of our yard and I was thinking of planting some stuff. Not a total gardening newbie but out of practice and there is some stuff I don't know. So...

--the soil in the raised bed is about 4 inches below the top of the wall. Do we need to add soil to build this up?

--the ground hasn't been worked in a while except for my tomatoes and herbs two years ago; planted nothing at all last summer; do we need to fertilize? If so, what kind would be best? We live in the U.S. in Zone 6.

Thanks! :-)

Comments

[earthspirits]

It would probably be a good idea to add some more soil, and also turn the soil and get rid of any weeds that may have sprouted, before you plant your new seedlings.

[rafiwinters]

Hi, I think I knew you were in this group--I might have joined at one point and then left because I was so discouraged about my garden fails--anyway, here I am, it's nice to see you here. So. Yeah, V the neighbor and I did decide to get some more soil, turns out there's some specifically formulated for raised beds, so we bought a couple large bags of that. She, being the young strong one (I'm middle-aged and have a bad back), did a bunch of soil-turning while I picked trash like cigarette butts and rusty bottle caps out of the soil to throw them away, and then stripped her old Christmas tree of its needles for mulch or compost. She's going to have someone chip up the trunk of the tree for more mulch.

[earthspirits]

Nice to see you too. : )

That all sounds excellent!

[harpers_child]

I don't think you need fertilizer, but it also couldn't hurt. I try to keep my various beds and containers topped up just so I don't have to reach down so far to weed.

[rafiwinters]

We haven't decided about fertilizer yet but we did get a bunch of soil that's made specifically for raised beds. That's tomorrow morning's task. (We both work flexible hours, so we can garden in daylight.)

[jadelennox]

if you're curious, you can send off soil samples off, usually to your local land-grant uni or agriculture uni (often the same school). I sent mine to UMass, who also told me things like "don't eat anything you grow in your side yard if you're pregnant or an infant, yikes!" Well, they didn't say "yikes". But it was implied. (I live in an urban area and there's a lot of mercury and lead in our soil. It's fine; I use raised beds.)

But honestly, you can't go wrong mixing in some compost to get more organic matter. You can buy it in bags for convenience, or if you need enough, your garden center might deliver from the truck. And your town/city might have municipal composting of leaf pickup, and many of them let people buy very cheap compost. But honestly the 40qt/1cf bag from the garden center, any brand, will do you just fine, if you don't need so much that it's unaffordable.

Beyond that I doubt you need any fertilizer, per se. If you do tomatoes again and they get blossom end rot then you might need some calcium, but you're probably fine.

UMass

[rafiwinters]

Ha ha, actually I thought about that--I'm in Rhode Island (and used to live in Boston). I can ask if they charge for that kind of thing. We're planning to compost and add some soil. Where-all do you live?

[eldriwolf]

When in doubt, mulch!

[rafiwinters]

We're going to get her old Christmas tree, which she kept on purpose, chipped up for mulch. I like the recycling and usefulness of this.

[ewt]

Sounds like there are a few questions here.

I would definitely top up the beds. What you use to do this with will vary according to what's available locally, what's appropriate locally for your soil and conditions, and how much you want to spend. If money isn't an issue, buying in some peat-free compost is unlikely to do any harm. If you've been composting your kitchen waste, using that would be great.

Whether or not to dig the soil is a big question and it depends on the existing soil texture and how intensively you want to grow. In general one of the great things about raised beds is less digging: stopping people from walking on the soil means it doesn't get compacted nearly as easily. But heavy clay soil can still get compacted, especially if it's been rained on with no plant cover. If this is the case, then working in some compost would be a good idea. Plant roots need air. But you could still just dump good organic compost on top and let the worms do the work, which would have the added benefit of being less disruptive of the soil food web. If there are a lot of weeds, put down a couple of layers of thick cardboard first and soak them with water. If you've kept the bed covered then bravo!

If you want to direct sow into the bed you need to pay more attention to the consistency of the top layer than if you're planning on using transplants (either grown yourself or store-bought). With transplants you have the option of topping up with straw, woodchips, leaf mould, grass clippings, or other mulch materials.

Tomatoes are heavy feeders, so it's worth bearing that in mind when deciding what to top up with. If you can get hold of organic certified well-rotted horse manure, that would be amazing. I wouldn't risk the non-organic sort as it can have aminopyralid contamination, which is a pesticide used on horse feed and lawns which is terrible for a number of garden crops. (This is also worth bearing in mind with straw and grass clippings.)

[rafiwinters]

We did decide to top up the bed with more soil. We got some that's formulated specially for raised beds so I think that will be all right. We're thinking about compost. Neighbor V thinks she will get a 2-compartment composter to keep outdoors and actually use our currently unused veg and produce ends. Also a nearby co-op sells compost for pretty cheap, you just bring your own bucket. :-)

[recently_folded]

The soil level depends upon two things: do the plants have enough room to root and can you reach them. Otherwise, it's really just an aesthetic decision.

The soil quality is a different issue. I live in a former stream drainage and have very mineral soil, but this applies even where soils are richer. It's a good idea to amend the soil at least annually or, with smaller amounts, spring and fall. I use a good quality organic fertilizer (don't put it on the week of a garden party as it smells a bit strongly for a bit) plus a mix of chopped green and brown—that is, clean non-weedy not-chemically-treated grass clippings plus the old leaves that I put on in the winter to keep the beds and perennials from dehydrating. For my fall mulch, I run a lawn mower over my pea and bean vines and include that. I also mulch further with this green/brown mix after plants are up enough to mulch around them, for water retention and weed suppression. This stays in place and gradually decomposes into the soil (thanks worms for your good work!) as more is added on top, and should help reduce compaction.

Because thinking on soil microbes has changed over recent years, it's no longer recommended to routinely dig a garden (and disturb them). Plants at the end of the season should be cut off rather than pulled, so that their beneficial microbe communities are there for the following year's new plants. New plantings should go in with as little disturbance as possible: just tiny holes to plant starts and gently brushing away the mulch to make a narrow row to sow seeds in minimal holes. I do still pull weeds, which I have rather few of after a few years of doing this, and of course some vegetables, like roots of the beet and carrot sort, still need to be pulled to harvest.

This is a gentle way of husbanding the soil, but I can say that my gardens, both flower and vegetable (and they all have some of both), get better every year.

[rafiwinters]

Oh, I didn't know that about the not-digging a garden! Thanks! We did a bit of digging the other day, but I'll let Neighbor V know what you said and we will rethink our strategy.

We did find plenty of earthworms, hurray!