Gardening Where You Are
All 50 States · Zone by Zone

The gardening advice that changes at your state line.

Most famous gardening books were written for one climate — usually a cool, mild, faraway one. This is a working handbook for the country you actually garden in: fifty states, every hardiness zone, every claim traced to your own state's university research.

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Written by L. H. Smith, PhD (Botany) · Sourced to Iowa State, Clemson, Penn State, Cornell, Colorado State & more

Hover the map you were never given: the 13 USDA hardiness zones, coldest to warmest.
Zone 1 · −60°FZone 13 · +65°F
The problem this book solves

A hydrangea that thrives in Portland can die three winters running in Minneapolis — and the book on your shelf won't tell you why.

The gardening classics are beautiful, and most of them are wrong for you. They were written for temperate, even, forgiving climates. They don't account for a Texas August, a Dakota January, a Georgia summer that never cools at night, or a Rocky Mountain season measured in weeks.

American gardeners have never lacked inspiration. What they've lacked is a single reference that starts from a different question — not "what's beautiful?" but "what actually works where you live?"

That's the whole book. Fifty states, organized the way the country really divides: by cold, by heat, by soil, by rainfall. Nothing borrowed from a climate you don't garden in.

What's inside

A complete reference, not a coffee-table book.

267 pages across eight parts and fifty chapters — built to be opened at the page that matches your yard.

Every hardiness zone covered

USDA zones 1–13, plus the heat-zone map most books ignore — the one that decides whether a plant survives August, not just January.

Region-by-region growing guides

The Southeast, the Mountain West, the Midwest, New England and more — each with its own soil story, calendar, and the mistakes gardeners make there.

Soil, tested and understood

How to read a soil report, correct pH, and build fertility — the invisible half of gardening that decides everything above ground.

Perennials that actually return

Which plants come back year after year in your conditions — chosen for survival first, and beauty a close second.

Traceable to the source

Load-bearing claims cite the university Cooperative Extension research behind them — the free public science your taxes already paid for.

Written to be used

A warm, plain-spoken voice that names the mistake before the method — so you understand why, not just what.

Why you can trust it

Every recommendation has a paper trail.

50
States covered
13
Hardiness zones
10+
Universities cited
267
Pages

Iowa State · Clemson · Penn State · University of Minnesota · University of Maryland
University of Missouri · Cornell · Rutgers · Colorado State · and more

Start free

Three things worth knowing before you plant anything.

A taste of the book's approach — genuinely useful on their own, no purchase required.

Climate & Zones

Your Hardiness Zone Is Only Half the Map

Everyone knows their cold zone. Almost no one knows their heat zone — and it's the one that kills plants in summer.

Read article →
Soil

The Soil Test That Prevents Most Failures

For about the price of two plants, your state lab will tell you why your last ones died. Almost no one does it.

Read article →
Technique

Water Deeply, Not Often

The most common watering habit is also the one that quietly guarantees shallow, fragile roots. Here's the fix.

Read article →

Get the complete handbook.

The full 267-page PDF — all fifty states, every zone, delivered instantly and yours to keep. Read it on any device, print the pages you need, and open it every season for the rest of your gardening life.

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LS
About the author

L. H. Smith, PhD

Botanist · Oregon

I spent a career studying how plants actually respond to the places they grow — and then wrote the reference I always wished American gardeners had.

PhD, Botany 41 international publications Based in Oregon Zones 1–13

The short version

I'm a botanist based in Oregon with a doctorate in botany and forty-one peer-reviewed papers published in international journals. For years my work lived in the technical literature — precise, rigorous, and almost entirely invisible to the people who spend their weekends actually growing things.

This book is an attempt to close that gap: to take the science that universities have quietly been publishing for a century and turn it into advice a gardener in any state can open, understand, and use that afternoon.

Why I wrote it

The gardening books people love most were, for the most part, written for someone else's weather. Their advice is real — for the climate it was written in. Carried across an ocean or a continent, it fails slowly and confusingly, and the gardener blames themselves.

Meanwhile, the best gardening information in America is already written, already free, and almost nobody reads it: the Cooperative Extension services at land-grant universities publish rigorous, region-specific guidance for their own states. It's scattered across hundreds of PDFs and buried under academic language. I gathered it, checked it, translated it into plain English, and organized it the way the country actually divides — by zone, by region, by soil.

The rule I wrote by
Every claim that a plant lives or dies on is traced back to a university's published research. If I couldn't source it, it didn't go in the book.

How the book sounds

Like a knowledgeable friend leaning on your fence, not a textbook. I tend to name the mistake before the method — because understanding why something failed is what stops it from failing again. It's warm, direct, and written in the second person, for you and your specific patch of ground.

Selected research & writing

A sample of my published work and general gardening writing. Replace the links below with your own — I've left the structure ready.

  • Peer-reviewed publication — journal title, yearRead →
  • Peer-reviewed publication — journal title, yearRead →
  • Peer-reviewed publication — journal title, yearRead →
  • General article — where it was publishedRead →
  • General article — where it was publishedRead →
Get the handbook Read the free articles
Free articles

Genuinely useful, whether or not you buy anything.

Each of these is drawn from the book's approach: start from the science, translate it into something you can do this weekend, and always point you back toward your own region.

Climate & Zones

Your Hardiness Zone Is Only Half the Map

Everyone knows their cold zone. Almost no one knows their heat zone — and it's the one that kills plants in summer.

Read article →
Soil

The Soil Test That Prevents Most Failures

For about the price of two plants, your state lab will tell you why your last ones died. Almost no one does it.

Read article →
Technique

Water Deeply, Not Often

The most common watering habit is also the one that quietly guarantees shallow, fragile roots. Here's the fix.

Read article →
← All articles
Climate & Zones

Your Hardiness Zone Is Only Half the Map

By L. H. Smith, PhD · About a 6-minute read

If you've ever bought a plant online, you've met the USDA hardiness zone. It's the number on the tag, the thing the nursery asks for, the reason a plant is labeled "hardy to zone 5." Most American gardeners can tell you their zone. Far fewer can tell you what it actually promises — and almost none know about the second map that matters just as much.

What the cold zone really tells you

The USDA Plant Hardiness Zone Map divides the country by one number: the average annual extreme minimum temperature — roughly, how cold a typical winter's coldest night gets. Each zone is a 10°F band, and each splits into an "a" and "b" half. Zone 5b is milder than 5a by about five degrees on that coldest night.

That's genuinely useful. It's also narrower than people think. Your hardiness zone is a statement about winter survival and nothing else. It says a plant can probably live through your coldest night. It says nothing about whether it can live through your summer.

1 2 3 4 5 6 7 8 9 10 11 12 13 −60°F +65°F COLDEST WINTER NIGHT, ON AVERAGE
The USDA map, in one strip: thirteen zones, each a 10°F step in how cold your worst night gets.

The map nobody hands you: heat

In 1997 the American Horticultural Society published a companion map that answers the opposite question. The AHS Plant Heat-Zone Map divides the country by the average number of days each year the temperature climbs above 86°F — the point at which many plants begin to suffer real cellular heat stress. It runs from Zone 1 (less than one hot day a year) to Zone 12 (more than 210).

This is the number that explains a mystery every Southern and desert gardener knows: a plant rated "hardy to zone 5" that survives winter effortlessly and then collapses in August. It didn't freeze. It cooked. Its cold-hardiness was never the problem.

The two-number habit
When a plant tag or catalog lists two ratings — say "USDA 5–9, AHS 9–2" — it's telling you both the coldest and the hottest place it can handle. In much of the South and Southwest, the second number is the one that decides survival.

Why this matters more in some places than others

In the upper Midwest and New England, cold is usually the limiting factor, and the USDA zone does most of the work. In the low desert and the Gulf South, heat does the killing, and the AHS zone matters more. A great deal of gardening disappointment comes from reading only the first map when you live in the country the second map was drawn for.

There's a third layer, too, that no national map can capture: your own yard. A south-facing brick wall, a low frost pocket, a windbreak, a patch of afternoon shade — these can move you half a zone in either direction within a single property. National maps give you the region. Your own observation gives you the garden.

What to do with this

  • Learn both your numbers. Look up your USDA hardiness zone and your AHS heat zone. Write them on the inside cover of whatever gardening book you use.
  • Read both ends of every plant rating before you buy — not just the cold end.
  • Trust your own yard over any map when they disagree. Maps describe averages across regions; your thermometer describes the place you actually plant.

Your region, in full

The handbook devotes a chapter to each major U.S. growing region — how cold and heat, soil and rainfall combine where you live, and exactly what thrives there. Both maps, applied to your ground.

See what's in the book

This article is general educational information. For guidance calibrated to your exact location, your state's Cooperative Extension service is free and excellent.

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Soil

The Soil Test That Prevents Most Failures

By L. H. Smith, PhD · About a 6-minute read

Here is the least glamorous, highest-return thing you can do as a gardener, and hardly anyone does it: send a cup of your dirt to a laboratory before you plant. For a small fee, a soil test turns the invisible half of your garden — the part doing most of the work — into a page of numbers you can actually act on.

Why guessing doesn't work

You can't see pH. You can't see a phosphorus surplus or a magnesium shortage. You can't see lead, which matters enormously if you're growing food near an older house or a former roadside. Soil looks like soil. Two beds that appear identical can behave completely differently, and no amount of experience lets you read those differences by eye.

So gardeners do the reasonable thing: they add a bit of everything. General fertilizer, some lime, some compost, a handful of whatever the garden center recommended. Sometimes it helps. Sometimes it makes a real problem worse — lime on soil that was already alkaline, nitrogen on soil that was short of something else entirely.

What the test actually tells you

4.05.5 6.57.59.0 ACIDIC ALKALINE Most garden plants: pH 6.0–7.0
pH controls which nutrients your plants can actually absorb. Most struggle outside the boxed range — even when the nutrients are physically present in the soil.

A basic report usually gives you pH (how acidic or alkaline the soil is), the levels of key nutrients like phosphorus and potassium, and your organic matter percentage. Better ones add tailored recommendations: exactly how much of what to add, for the specific crop you name.

pH is the one that quietly runs everything. It doesn't feed plants directly; it decides how much of the food already in your soil they can reach. Iron can be abundant and still locked away from the plant if the pH is wrong — which is why a plant can starve in soil that a lab report shows is full of nutrients.

Where to get one — and why the source matters

Skip the plastic probe from the hardware store; the cheap ones are notoriously unreliable. Instead, use your state's Cooperative Extension service, run through its land-grant university. Nearly every state has one. They'll tell you how to pull a representative sample, mail it in, and read the results — and their recommendations are calibrated to your region's actual soils, not a national average.

The cost is typically modest — often somewhere around the price of a couple of perennials, though it varies by state and by how detailed a test you request. Against a season of plants that fail for a reason you could have known in advance, it's the best money in gardening.

A quick test you can do today
Squeeze a handful of moist (not wet) soil and try to roll it into a ribbon between thumb and finger. Barely holds together? Sandy — drains fast, dries out. A short ribbon that cracks? A balanced loam. A long, bendy ribbon? Heavy clay — holds water and nutrients, but compacts. It won't give you pH, but it tells you how your soil handles water, which shapes nearly every other decision.

The habit worth building

Test a new bed before you plant it, and re-test an established one every few years — sooner if things start underperforming. Soil changes: it acidifies over time in rainy climates, drifts alkaline in dry ones, and shifts with everything you add. A test every two or three years keeps you working from facts instead of hope.

Read your report like a pro

An entire section of the handbook walks through a real soil report line by line — what each number means, how to correct pH safely, and how to build lasting fertility for your region's soil.

See what's in the book

General educational information. Your state's Cooperative Extension office offers soil testing and can interpret your specific results for free or at low cost.

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Technique

Water Deeply, Not Often

By L. H. Smith, PhD · About a 5-minute read

Most people water their gardens the way they'd want to be watered: a little, often, especially when it's hot. It feels caring. It's also, for established plants, close to the worst thing you can do — and the reason so many gardens wilt the moment someone goes away for a week.

Roots grow toward water

A plant builds its root system wherever it reliably finds moisture. Water lightly every evening and you keep the top inch or two of soil damp — so that's exactly where the roots stay. You've trained a shallow, surface-bound root system that depends entirely on you and can't survive a single missed day.

Water deeply and less often, and moisture penetrates well below the surface. The roots follow it down, building a deep network that reaches reserves the summer sun never touches. That plant can shrug off a hot, dry week — and a forgotten weekend.

Frequent & shallow Deep & infrequent
Same plant, two watering habits. The roots grow to match where the water is.

What "deeply" actually means

The goal is to moisten the soil to the depth of the plant's roots, then let the top few inches dry out before you water again. That drying period is not neglect — it pulls air into the soil and signals the roots to keep reaching. Constantly saturated soil, by contrast, suffocates roots and invites rot.

A rough starting point for many established gardens and lawns is about an inch of water a week, from rain or hose combined, delivered in one or two good soakings rather than seven light sprinkles. But "an inch a week" is a national average pretending to be a rule. Sandy soil drains fast and wants smaller, more frequent drinks; clay holds water and wants less. Your climate, your season, and your soil all move the number.

How to check depth
After watering, push a screwdriver or a wooden dowel into the soil. It slides easily through moist ground and stops where the soil is dry. That's a free, instant read on how deep your water actually went — far more reliable than guessing from the surface.

The exceptions worth knowing

Seedlings and brand-new transplants haven't built deep roots yet, so they genuinely do need lighter, more frequent watering until they establish — usually a few weeks. Container plants dry out fast and often need daily attention in summer heat. The deep-and-infrequent rule is about established plants in the ground, which is most of your garden most of the time.

Water in the early morning when you can, so leaves dry quickly and less is lost to evaporation. And water the soil, not the foliage — wet leaves overnight are an open invitation to disease.

Watering, by region and season

How much and how often depends heavily on where you garden. The handbook's regional chapters include watering guidance tuned to each part of the country — including the winter watering that keeps evergreens alive in dry-winter zones.

See what's in the book

General educational information. Local watering needs vary widely; your state's Cooperative Extension service can advise for your soil and climate.