grow your own, nevada! spring 2012: raised bed gardening

Angela O’Callaghan, PhD

Social Horticulture Specialist

University of Nevada

Cooperative Extension

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Different definitions:

• Area of amended soil slightly

higher than surroundings

• Discrete structure containing

varied kinds of fill

Can be built to size, height

and mobility needs of gardener

Can be made of

brick, block, wood,

plastic, etc.

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• Plastic can

look like

almost

anything,

including

wood

• Control over plants’ environment:

–Fill, water, fertility management

• Varied bed height for convenience

• Few weed problems

• Discrete size, easier to work

• Smaller area to shade or protect from frost, when necessary

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• Can be

temporary or

permanent

• Must be filled

with fertile,

well-drained

mix

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May be:

•Unglazed clay (terra

cotta)

•Glazed clay

•Plastic

•Wood

•Biodegradable material

•Large

•Small

•Sitting

•Hanging 2/25/2013 14

Plastic –

Can look like almost any material

Holds water well

Low cost

Wood

Good drainage

Rustic appearance

Can be expensive

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• How much $$ do you want to

spend?

• How much space can you dedicate

to it

• How convenient will it be

• Who will build it

• http://www.cleanairgardening.com

/raised-bed-gardening.html

• Lumber ~ $1/linear foot

– Walls & uprights

– 2” x 10” x length of choice x height of choice

– 4” x 4” x height of choice

– May need more uprights for long, tall bed

• Hardware ~ $5 per upright

• A 20” high, 10’ long, 4’ wide bed ≈ $125

• ~ $1 per

• ~ 2” x 2” x 8”

• Need ~ 420 bricks for

–10’ long x 4’ wide x 20” high

• Mortar (2) ~ $20

• Cost ≈ $440

• Bed = 10’ long x 4’ wide x 18” high

• ~ $1.50/block (16” x 6” x 6”)

• ~ 68 blocks ~ $102

• Mortar 2 bags ~ $20

• ≈ $142

• Very wide price range

• May mimic wood or block

• Does not survive Nevada conditions

• Potting mix

• “Planter mix”

• Potting soil

• Other

• Peat moss, perlite, vermiculite, soluble fertilizer

• Chipped wood, composted manure

• Field soil, peat moss, perlite

• Varying amounts of organic matter in a matrix

• Potting mix

• “Planter mix”

• Potting soil

• Other

• Expensive, dries out quickly

• Materials may not be fully

composted, could burn roots

• May contain seedling pathogens

• Varying problems, poor water

holding, incomplete composting,

fertility may be questionable

• A raised bed is a confined space

• It makes sense to plant annuals (or

plants that we treat as annuals)

• We treat most of the vegetables

we grow as annuals, whether they

are or not

• Many of our common vegetables

are not

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• Vegetables are often grown as annuals,

although they may technically be something

else

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• Lettuce

• Spinach (not New Zealand or Malabar

spinach)

• Chard

Usually only want the

first years growth –

leaves, roots, stalks;

second year it

flowers

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Flowering broccoliFlowering carrots

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• Artichokes

• Jerusalem artichokes

• Sweet potatoes

• Tomatoes

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• Annuals will flower and produce seeds once

before dying

• Biennials will flower and produce seeds once,

and only if they have experienced a chilling

period with short days

• The desired part of many biennial vegetables

is produced only in the first year

• Perennials can produce for several years

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Express the gardener’s

taste

Sophisticated

Rustic

Urban

Antique

Eclectic

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A pot is a miniature garden plot

As long as there is sufficient room

for roots and drainage, it can

work

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Such as condensed

foam

• Can look like

decorative clay without

the weight or cost

• Can be thicker-walled

than plastic for better

insulation402/25/2013

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• Insulation

• Conserves water

• Moderates heat

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Material

• Brick

• Block

• Wood

• Plastic

Problem

• Expensive, may need

mortar

• May release salt

• Expensive, may not

withstand extreme

weather

• Expensive, will not

withstand extreme

weather

• From P. Allen Smith’s website

•Certain vegetables grow smaller if

planted close together

•This technique is best for leafy

vegetables

•Less for fruiting vegetables

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• Most herbs are grown either for leaves

(basil, oregano, mint) or flowers (dill)

• Many can grow as companion plants

• May be used as houseplants

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• Herbs can be

somewhat crowded

as long as there is

sufficient air

circulation

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Even if you have a large

space

Grow

aggressive

plants in pots

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• Each plant removes available

nutrients that it needs

• In a confined area like a raised bed

the soil or mix may become

depleted

• These need to be replaced

• Native desert soils are generally infertile

• Soils placed around construction are generally worse

• Gardeners need to increase fertility

• Soluble fertilizers are commonly used– May be organic or conventional

– Very convenient

– Concentrated levels of nutrients (conventional)

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• Commercial all-purpose fertilizers

have nitrogen, phosphorus and

potassium

• The % of each (in that order, always)

is listed on the package

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• In addition to NPK, several other micronutrients may be present in product.

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If you want to grow

organically, then

conventional

fertilizers are a no-no

If you want what is

usually most

convenient, then

organic methods

might be too much of

a bother

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Irrigation, hose, watering can

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• Ongoing fresh crop of plants

• Some plants are only used fresh

• For instance, leafy greens

• For continual supply, calculate:

– time from planting to mature plant

– amount that is planted at any one time

– How long plant(s) will stay usable

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• How long from seed to mature

plant?

• How long will a first crop last?

• How much of a variety does the

gardener (and family) eat?

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• Have salad green that takes 45 days from

seeding to maturity at 60 (early spring)

– Plant on February 1

– Plants mature about March 18, but can begin

eating on March 13

– If one planting yields 14 salad days, by March

27, first crop is finished.

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• Want to have continuous salad

• Need new crop by March 27

• At 75 plants grow faster, say 42 days to

maturity

• Count backwards six weeks from Mar 27

• Begin planting by February 13

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• Plant earlier in spring

• Grow later in fall

• Grow longer despite seasonal

changes

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• Right plant, right place

• Properly fertilized

• Properly watered

• Receives enough light

• Sheltered from excess light, wind, heat,

cold

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• Mulch

• Wall o’Water

• Floating row covers

• Cloches

• Shade cloth

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• Straw

• Pine needles

• Shredded

wood