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.
How many vines it can carry — an estimate
Sowing depth — an estimate
Frost tolerance — an estimate
Days to maturity — an estimate
Spacing in row — an estimate
Mature height — an estimate
Mature spread — an estimate
Rules that apply to amaranth
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
If you skip this, the planting fails. The planner won’t allow it.
How it works: The season's accumulated growing degree days (a running total of its warmth) against the total the crop needs to mature, or the crop's days to maturity against the number of frost-free days.
Evidence: checked against 3 sources in the research-based literature.
Once you know the average dates of the last frost in spring and the first frost in fall, count the number of days between. If the “days to maturity” figure for a desired vegetable is a larger number of days and the “frost tolerance” column indicates “none,” the sad truth is that particular vegetable probably won’t grow to maturity.
… high elevation areas don’t accumulate enough “growing degree units” (GDUs, also called growing degree days and heat units) to support some of the most coveted warm season vegetables
Remedy
Start it indoors and transplant it, choose a variety with fewer days to maturity, or skip this crop at this site.
If you skip this, you lose real yield. The planner warns you.
How it works: Cercospora beticola, the leaf spot of beet, chard and spinach, survives on infested residue and in soil for up to three years and carries over on lambsquarters and pigweed; spinach downy mildew (Peronospora effusa) leaves oospores in the soil for a few years and rides on seed. A three-year break outlasts both.
Evidence: checked against 7 sources in the research-based literature.
Rotate out of land where spinach was grown for at least 2-3 years
Do Rotations Matter within Disease Management Programs? Cornell Vegetables
We summarise this source in our notes rather than quote a line from it.
Remedy
Plant them in different ground, or wait until 3 years have passed since this ground last held them. Bury or remove the old leaves, keep lambsquarters and pigweed out of the bed in between, and buy clean seed.
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.
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.
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
