Soil Proprietorship: The Plot Thickens
Southwest Yard & Garden by Dr.
Marisa Thompson
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| Tomato seedlings have just sprouted at the NMSU Agricultural Science Center at Los Lunas. We hope to compare covered and uncovered tomato plants to see if we can reduce curly top virus infection rates, conserve water, and increase yields. Photo credit M. Thompson. |
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Carol
B., Los Lunas
Answer:
I’ve gotten variations on this question from several friends through the years,
and have seen a huge increase in the number of questions about soil for
backyard gardening on local Facebook groups in the past few weeks. My guess is
that people are reluctant to plant directly into the ground because of three
major reasons: 1) weed pressure, 2) accessibility, and 3) they’ve tried digging
a few holes and the soil is so compacted they gave up.
If you don’t have accessibility concerns and you can stand to dig
a garden plot a few inches deep, keep it relatively weed-free by pulling weeds
regularly, and plant directly into the soil, that may be your best bet. Containers
and raised beds have benefits, but they also have some downfalls. For one, they
tend to dry out much more quickly. Drainage is necessary, but containers can
dry out so fast plants can wilt between waterings. They’re also more exposed to
the elements, so the soil and roots can get much hotter in the summer (and
colder in the winter) than they do in the ground. Consider painting pots white
or a pale color to reflect more sunlight so they stay a little cooler.
Whether you’re planting in the ground or in containers, mulching
on top with any fibrous organic material (straw, leaves, woodchips) will help
in multiple ways. Three to four inches of mulch helps suppress weed germination
and growth, holds moisture in the soil, keeps the rooting area cooler in summer
(and warmer in winter), prevents water and wind erosion, and prevents surface
crusting (which inhibits water penetration). Over time, mulching also provides
much-needed nutrients that feed beneficial soil organisms, increases organic
matter and improves soil texture, and eventually enhances the soil’s ability to
store nutrients for plant root uptake. Of course, if you’re direct-seeding your
garden beds or containers, adding a thick layer of mulch too soon can inhibit seed
sprouting. You can either transplant seedlings and add mulch around them or
scoot the mulch away in the spots where you’re planting seeds.
But back to the question of planting mix. To a large extent, it
really depends on two things: what are you trying to grow and what kind of
existing soil you have at home. Warning: If your yard is full of weeds, your
soil is likely full of weed seeds too. And the soil under the mulch will keep
that weed seed bank for many years to come.
I asked my farming friend, Dr. Willy Carleton, who grows chiles,
sweet potatoes, and all sorts of other vegetables outside of Española, what
advice he’d like to share. Willy stressed that soil texture is extremely
important. Think “fluffy with good drainage.” If you shovel soil from your yard
into containers or beds, the result may be anything but fluffy with good
drainage. If your yard soil is sandier, the plants theoretically would stand a
better chance because of better drainage.
I also reached out to longtime gardener and certified desert
landscaper, Tsu Dho Nihm, for sharable tips: “Do not use cardboard as a weed
blocker under a raised bed” because it restricts oxygen flow, which is harmful
to beneficial organisms like earthworms. And “don’t put rocks in the bottom [of
containers]. They don’t help with drainage. Don't worry about amending and
fertilizing until you have tried growing some things and see how they do. Don't
reach for a ‘fix’ until you are sure what the problem is. If you have a
problem, check your watering practices first.” Tsu Dho Nihm’s blog (http://lazygardens.blogspot.com)
offers great options for no-tool, cheap raised bed plans and frost shelters
(which can double as shade shelters), among other local gardening topics. For
more on the cardboard comment, visit http://gardenprofessors.com/the-cardboard-controversy/.
For more on why to skip putting rocks in the bottoms of pots, visit https://nmsudesertblooms.blogspot.com
and search “drainage” for my 2018 blog post about fungus gnats.
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| NMSU Extension Circular 457, “Home Vegetable Gardening in New Mexico” (https://aces.nmsu.edu/pubs/_circulars/CR457/welcome.html) |
According to NMSU Extension Circular 457, “Home Vegetable
Gardening in New Mexico” (https://aces.nmsu.edu/pubs/_circulars/CR457/welcome.html),
one of the easiest ways to improve soils is to add organic matter, such as
livestock manure. See Circular 457 for more info on how much organic matter to
apply and when--and when NOT!
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| Circular 694B “Soil Health—Importance, Assessment, and Management” (https://aces.nmsu.edu/pubs/_circulars/CR694B/welcome.html). |
Other helpful NMSU Extension publications include Circular 687, “Managing
Organic Matter in Farm and Garden Soils” (https://aces.nmsu.edu/pubs/_circulars/CR687/welcome.html),
and
Circular 694B “Soil Health—Importance, Assessment, and Management” (https://aces.nmsu.edu/pubs/_circulars/CR694B/welcome.html).
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Whatever you decide to use for your gardening needs, take lots of
pictures and let me know how it grows. I’d love to survey you all at the end of
the season to see what worked and what didn’t.
For more
gardening information, including
decades of archived Southwest Yard & Garden columns, visit the NMSU
Extension Horticulture page (http://desertblooms.nmsu.edu/),
follow us on social media (@NMDesertBlooms), or contact your County Extension
office (https://aces.nmsu.edu/county).
Marisa Thompson, PhD, is the Extension Horticulture Specialist for New
Mexico State University and is based at the Agricultural Science Center at Los
Lunas.
Edible New Mexico Magazine article crosslink -- GROWING YOUR FUTURE FAVORITE TREE
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