Many of our estimates come from an extension page we’ve read that gets close without pinning the number down. Others are still our own best guess, and on some the sources disagree. Treat them all as a starting point.
Mature height — an estimate
Mature spread — an estimate
Soil pH — an estimate
Years the seed stays good — sources disagree
Rules that apply to New Zealand spinach
Don't sow or set out tender crops before your last frost date Well established
Don't sow or set out tender crops before your last frost date
Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself. Promising
Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself.
If you skip this, it still grows, just less well. The planner suggests it.
How it works: Cold hardiness. Hardy crops tolerate hard frost and half-hardy crops tolerate light frost, so they can occupy the ground weeks before frost-tender crops are allowed in. The offset is measured from the last spring frost.
Evidence: checked against 2 sources in the research-based literature.
Long-season warm crops are started indoors several weeks before the last frost and set out after it. Tomato and tomatillo go about six weeks ahead, pepper and eggplant about eight, basil six. Promising
Long-season warm crops are started indoors several weeks before the last frost and set out after it. Tomato and tomatillo go about six weeks ahead, pepper and eggplant about eight, basil six.
If you skip this, it still grows, just less well. The planner suggests it.
How it works: A frost-tender crop with a long days-to-maturity cannot mature if it is only direct-sown after the last frost, because the frost-free window is too short. A head start under cover buys the weeks the season lacks; the seedling is set out only once frost has passed, so the transplant date is still frost-gated.
Evidence: checked against 3 sources in the research-based literature.
If you skip this, the planting fails. The planner warns you.
How it works: On a clear, still night leaves lose heat to the open sky, so a leaf can fall to freezing and ice can form in it while the thermometer, a couple of meters up, still reads a few degrees above.
Evidence: checked against 7 sources in the research-based literature.
Frost occurs when air is warmer than 32°F but plant tissues drop to 32°F or below because plants radiate (lose) heat into the atmosphere, especially during cool, clear nights.
Radiation frosts occur on calm clear nights that lack cloud cover to hold in heat.
Remedy
The evening before, cover the crops at risk with a sheet or frost cloth, never plastic, reaching the ground and loose at the bottom so the soil's warmth can rise under it, and take it off in the morning. A cover helps least in a long, hard freeze.
If you skip this, it still grows, just less well. The planner suggests it.
How it works: Heat is what sends lettuce and spinach to seed. These four are warm-season leaf crops that grow best in the heat that ends a lettuce crop, so the same months are their season. Dry soil or a hungry plant sends them to flower too, and then the leaves turn bitter and growth stops.
Evidence: checked against 6 sources in the research-based literature.
Milpa Gardens. "New Zealand spinach (Tetragonia tetragonioides)." https://milpa.garden/plants/tetragonia-tetragonioides/
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