What the map reads from a piece of land, and what you can do with it.
Draw a line around any property in the lower 48 states. Land Assay pulls the government's own surveys for exactly that ground (elevation, soil, weather records, aerial photos) and turns them into answers a homeowner can use.
Six things it reads
Each one comes from a public national dataset, fetched for the boundary you draw.
The lay of the land
Contours, slope, which way each part faces, and the keylineIn plain wordsWhere the ground is flat enough to build or garden, where it's steep, and which parts face the sun.
- Pick the spot for a garden, shed or driveway
- Know where mowing, digging or building gets hard
- Plan steps, terraces or paths across a slope
- Find the keyline: the contour through the point where a valley stops being steep, the line to lay water, paths and tree rows along
Water
Runoff paths, wet spots, where water gathers, mapped wetlandsIn plain wordsWhere rain runs across the property, where it collects first, and where it leaves; and which parts the National Wetlands Inventory maps as wetland (from aerial photos, so it can miss some).
- See why a yard or basement stays wet, and which way the water comes from
- Place downspout extensions, a rain garden or a rain barrel
- Keep new building out of the wettest ground
Soil
USDA soil survey: drainage, depth, pH, and its septic and house ratingsIn plain wordsWhat is under the grass, how fast it drains, how deep it goes before rock or water, and how it behaves in a freeze.
- Choose between raised beds and in-ground beds
- Know whether ground stays soggy in spring
- Expect frost heave under posts and footings
- See what the survey rates the soil for a septic field, a basement or a rain garden (a rating for the soil map unit, not a perc test)
The growing season
Frost dates, rain by month, hardiness zoneIn plain wordsWhen the last spring frost and first fall frost usually come, how long the season runs, and which months run short of water.
- Set a planting calendar for that address
- Know which months need watering
- Pick fruit trees that live through the winter
Sun and wind
Sun path by season, winter shade, prevailing windsIn plain wordsWhere the low winter sun reaches, where the high summer sun does, and which side the cold wind hits.
- Put the garden, patio or greenhouse in real sun
- Plant a windbreak on the right side
- Judge a spot for solar panels before calling an installer
What grows there
150 useful plants, matched to the site, Minnesota natives markedIn plain wordsTrees, berries and helper plants rated hardy in that zone and suited to the soil moisture the survey maps there. In Minnesota, the ones native to the state are marked (statewide: some grow wild only in part of it).
- Buy plants that survive the first winter
- Build a planting around one fruit tree that feeds and protects it
- Find what takes the wet corner
Three numbers worth knowing
Water that 1,000 square feet of roof sheds in a one-inch rain. The map shows where that water goes next.
An example hardiness zone: the average coldest night of the year falls between −25 and −20 °F. The map looks up the zone for your zip code.
About how much ground one pixel of the aerial photo covers when you zoom all the way in, from USDA's National Agriculture Imagery Program.
Who it helps
Homeowners
- A wet yard or basement: see which way water runs toward the house and where to send it away.
- A garden that works: the flat, sunny, well-drained ground, with frost dates for that address.
- Trees and shrubs that live: a plant list for your zone and your soil.
- Cold wind: which side needs a windbreak or a sheltered patio.
Buyers and real estate agents
- Before an offer: where water sits, how the soil drains and how long the season runs, on one screen.
- In a listing: a plain page about the land that answers a buyer's first questions, especially for acreage, hobby farms and big yards.
- Before building: which part of a lot is flat, dry and sunny.
- Several properties: write to hello@landassay.com.
How to use it
Find the property
Type the address on the map and zoom in, or, standing on the land, tap Use my location.
Draw the boundary
Press Draw it on the map and tap each corner of the lot, going around it; tap the first corner again to close it. A short guide on the Start tab walks you through it. In Minnesota, Tap your parcel instead and the county's parcel lines become the boundary.
Read the site
Press Analyze my site. Terrain, water, soil, season, sun and wind load in about a minute. Then open Plants for what grows there.
The free map and the written report
| Map · free | Report · $49 | |
|---|---|---|
| Same six readings | Live layers you turn on and off | Written up for the boundary you drew |
| Soil and wetlands | Each soil's share in acres, the survey's septic, house and rain-garden ratings, mapped wetlands | The same, on the soil and water pages |
| Format | On screen, with a quick printable summary | 8 to 13 designed pages with the aerial photo and your address on the cover |
| Your goals | A hint for each goal you tick | One page reading the land for every goal you tick, with this site's numbers |
| Design tools | Draw beds, trees, swales and paths; plant finder with a Minnesota natives filter; guild builder | Your drawn plan checked against the design principles (up to three pages), a starter planting, and first steps in order |
| Keeping it | Saved in your own browser, or sent as a view-only link with Share | A private link you can keep, print or save as a PDF |
Your goals, read for this land
Tick what the land is for on the map's Start tab: food, water, income, wildlife, a shared space, a place to heal and make things, low upkeep. The report reads the property again for each one, with its own numbers: how much ground will grow food, how long the season runs, where water gathers, which side the cold wind hits. Pick experienced and every goal starts ticked (untick what doesn't apply), and the report adds the technical figures.
Your plan, checked
Draw the plan on the Design tab first, and the report checks each piece against the same elevation, soil, sun and wind data: swales level across the slope, diversion drains with a gentle fall to a pond or a safe outlet, ponds on soil that holds water, garden beds near the house and out of wet or frosty low spots, trees hardy for the zone and suited to the soil, windbreaks on the side the winter wind comes from, compost and animal yards that don't drain toward the water, paths that don't run straight downhill. Each gets fix, check or placed well, with the measurement behind it. These are rules of thumb from permaculture and extension guides, not a site visit.
What it isn't
- A survey. The boundary is the line you draw, or in Minnesota the county's tax-map parcel lines; neither is a surveyed legal line.
- A perc test, septic design or well report.
- A zoning, flood-zone, easement or title check. The county answers those.
- An inspection of any building.
- A guarantee for one exact spot. The surveys are mapped at neighborhood scale; a shovel, a soil test and a walk in a hard rain still beat them.