The Seed Packet Instructions
A gardening guide gives these directions for a variety of tomato:
"Sow seeds indoors six to eight weeks before the last expected frost. Keep soil at 70–75°F for germination, which typically takes 7–14 days. Once seedlings have two true leaves, transplant them into larger pots. Harden off seedlings by setting them outdoors for one hour more each day over seven to ten days before planting in the garden. Do not set plants out until nighttime temperatures stay above 50°F. Plants set out too early often grow slowly and may not recover."
Priya lives where the last expected frost is May 10. She sows seeds indoors on March 20. Her seedlings sprout on April 2. By April 20 they have two true leaves. She wants to plant in the garden on May 1, when nighttime temperatures are forecast to be 46°F.
1. Is Priya's sowing date within the recommended window? Show the arithmetic.
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The guide says sow six to eight weeks before the last frost. Priya's last frost is May 10.
- Six weeks before May 10 is March 29.
- Eight weeks before May 10 is March 15.
So the window runs from March 15 to March 29. Priya sows on March 20, which falls inside that window. Her sowing date is fine.
The trap here is direction: "before" means counting backward from the frost date, not forward from the sowing date.
2. Priya wants to plant out on May 1. Using the temperature rule and the hardening-off rule, explain whether May 1 works and what she should do instead.
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Two rules block May 1.
- Temperature: the guide says do not set plants out until nighttime temperatures stay above 50°F. The forecast for May 1 is 46°F, which is below 50°F. So May 1 fails the temperature test.
- Hardening off: seedlings must be set outdoors for one hour more each day over seven to ten days before garden planting. If Priya has not started this, she cannot plant on May 1 regardless of temperature.
What she should do: wait until nighttime temperatures are reliably above 50°F (after May 10 is the natural target, since that is the last expected frost), and begin hardening off at least seven to ten days before that planting date. May 1 is too early on both counts.
3. The guide says early-set plants 'often grow slowly and may not recover.' What is the logical relationship of this sentence to the temperature rule, and how should it affect Priya's decision?
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The sentence states a consequence of violating the temperature rule; it is the cause-effect reason behind the instruction. The temperature rule is the directive, and this sentence explains why the directive exists: setting out too early causes slow growth and possible failure to recover.
For Priya, this raises the cost of planting on May 1. It is not merely a rule to follow but a warning that the outcome is likely poor and possibly permanent ("may not recover"). A careful reader treats the warning as strengthening the case for waiting past the cold nights rather than gambling on May 1.