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Sources

Where the facts come from

Every factual claim on this site links to its source. This is the full list.

How we checked

Each fact was written alongside its source. Our build script stores the source text and, for every fact, checks that the key words and figures really appear in it. 124 of 124 checks passed when this site was last built (checked 30 Oct 2026). Where we couldn’t read a source, we left the claim out. We quote short phrases only, and never reproduce anyone else’s images.

The court case

For Nix v. Hedden we went to the record: the page images of 149 U.S. 304 in the U.S. Reports at the Library of Congress, with the exact wording checked against the text on Justia and Cornell Law School’s Legal Information Institute (the Library of Congress text layer is scanned, so it has typing errors). The plaintiffs are named in the report only as “Nix et al.”, so we call them the importers.

Figures that change

Recommended variety lists and disease-resistance ratings can change. Facts like these are marked “checked 30 Oct 2026”.

What we leave out

This is a site about growing tomatoes and their history. We don’t give health, nutrition or diet advice, even where a source does. We don’t recommend pesticides or other chemicals. Our drawings are not identification guides: for a diagnosis, use the pages linked here. Where sources disagree, we show both rather than choose silently.

Royal Horticultural Society (RHS) (4)

Garden Organic (3)

University of Minnesota Extension (1)

Royal Botanic Gardens, Kew (1)

Encyclopaedia Britannica (1)

The US Supreme Court record: Nix v. Hedden (1893) (3)

When sources disagree

Where sources give different figures, we show all of them, with links, and say how we handle it.

How far apart?

How we handle it: The RHS gives 45–60cm (18–24in) in the ground, depending on how big the plants will grow; Garden Organic gives 30–45cm for outdoor plants; University of Minnesota Extension gives two to three feet in all directions for vining types, with bush types closer. The RHS also says to check the seed packet. We show all three.

When to sow?

How we handle it: The RHS says late February to mid-March for a greenhouse crop and late March to early April for outdoor plants; Garden Organic says March or April; Kew sows in April with some artificial heat; UMN counts back five to six weeks from planting out. They are written for different places and set-ups, so we give each.

How deep, and how warm, for seeds?

How we handle it: The RHS gives about 18°C (64°F) for germination; UMN says keep seeds at 75–85°F (about 24–29°C) on a heating mat. Garden Organic says sow 0.1cm deep; UMN says a quarter of an inch (about 0.6cm). We show both.

When to plant out?

How we handle it: The RHS goes by air temperature (reliably above 16°C, 60°F, in early summer); Garden Organic by the plant (when the first flowers open) and its calendar (late April to early June); UMN by frost and soil warmth. These are three ways of judging the moment, so we show all three.

How long before tomatoes go back in the same place?

How we handle it: The RHS says don’t grow tomatoes in the same bed in consecutive years; UMN says choose a spot where tomatoes and their close relatives haven’t grown for the past three or four years. UMN’s gap is longer.

How long until harvest?

How we handle it: Garden Organic’s cards give about 12–16 weeks indoors and about 16–20 weeks outdoors; the RHS says tomatoes start to ripen from midsummer, depending on variety, weather and fruit size. We quote each with its source.

Where did the tomato come from?

How we handle it: These don’t clash. Britannica and Kew both say the tomato came from the Andes; Britannica adds that it is thought to have been domesticated in Mexico. Where a wild plant grew and where it was first farmed can be different places.