Creates a zone-aware planting calendar based on USDA hardiness zone and frost dates, with planting windows for vegetables, herbs, and cool/warm-season crops. Includes succession planting schedules and seed-starting timelines.
A skill is a written procedure a bot loads when a job calls for it. This one is a single file, SKILL.md, and the whole file is on this page.
Creates a zone-aware planting calendar based on USDA hardiness zone and frost dates, with planting windows for vegetables, herbs, and cool/warm-season crops. Includes succession planting schedules and seed-starting timelines.
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A user wants to stagger plantings of lettuce, radishes, beans, or other short-season crops for continuous harvest
A user is planning a fall or winter garden and needs to count backward from their first fall frost
A user asks about soil temperature requirements before direct sowing warm-season crops
A user wants to know which crops they can still plant given a mid-season start
A user in a hot or tropical climate needs a planting framework not based on frost dates
Do NOT use when:
The user needs spatial layout, bed organization, companion planting pairings, or spacing decisions -- use vegetable-garden-planning
The user has a plant that is yellowing, wilting, showing disease symptoms, or failing to thrive -- use plant-care-troubleshooting
The user is asking about watering schedules, potting mix, or repotting for indoor plants -- use indoor-plant-care
The user needs a lawn aeration, overseeding, or fertilization schedule -- use lawn-care-schedule
The user is asking about perennial flower beds, bulb planting for ornamentals, or landscape shrub timing -- the frost-date framework still applies but the specific crop data in this skill is for edible gardens
The user wants pest identification or integrated pest management strategy -- use garden-pest-management
Process
Step 1: Gather Zone, Frost Dates, and Garden Context
Accurate planting calendars require three anchoring data points: USDA hardiness zone, last spring frost date (LFD), and first fall frost date (FFD). Never proceed with generic calendar months alone.
Ask the user for their USDA zone or ZIP code if they have not provided it. Zones are available from the USDA Plant Hardiness Zone Map, which was updated in 2023 and is significantly more granular than earlier versions.
Use the zone as a starting estimate only. Actual frost dates vary within a zone due to microclimates: low-lying areas, proximity to large bodies of water, urban heat islands, and slope orientation can shift local frost dates by 2-4 weeks from zone averages.
Always recommend that the user verify their specific frost dates with their state's cooperative extension service or NOAA's climate normals database (ask a local master gardener or county extension agent if unsure).
Collect secondary context: How large is the garden? Is it raised beds, containers, or in-ground? Do they have access to row covers, cold frames, or a greenhouse? These tools shift effective planting windows by 2-6 weeks and must factor into the calendar.
Ask which crops they want to grow. Do not build a 40-crop calendar for someone who only wants tomatoes, peppers, and lettuce -- tailor the output tightly to their stated goals.
Frost date reference by zone (NOAA 30-year climate normals, average dates):
Zone
Last Spring Frost (LFD)
First Fall Frost (FFD)
Avg Growing Season
3a
June 1-15
Aug 15-Sept 1
75-90 days
3b
May 15 - June 1
Sept 1-15
90-110 days
4a
May 15-25
Sept 15-25
105-130 days
4b
May 1-15
Sept 25 - Oct 5
120-140 days
5a
April 25 - May 5
Oct 5-15
140-155 days
5b
April 15-25
Oct 15-25
155-170 days
6a
April 5-15
Oct 25 - Nov 5
165-185 days
6b
March 25 - April 5
Nov 5-15
185-205 days
7a
March 15-25
Nov 10-20
200-220 days
7b
March 1-15
Nov 20 - Dec 1
220-240 days
8a
Feb 20 - March 5
Nov 28 - Dec 10
240-265 days
8b
Feb 10-20
Dec 8-20
265-285 days
9a
Jan 20 - Feb 10
Dec 15 - Jan 1
285-310 days
9b
Jan 10-20
Dec 20 - Jan 15
310+ days
10+
Frost rare or absent
Frost rare or absent
Year-round
Step 2: Classify All Requested Crops by Temperature Tolerance
Every planting decision flows from how a crop responds to cold air, cold soil, and heat. Misclassifying a crop is the most common source of planting errors.
Category 1 -- Hardy cool-season crops (survive hard frost to 26 degrees F, germinate in 40-degree-F soil):
Can be direct sown outdoors 4-6 weeks before LFD when soil is workable (not frozen or waterlogged)
Can be transplanted even earlier if using row covers
Peppers and eggplant will sit dormant or develop chilling injury if transplanted into soil below 60 degrees F -- warmer is always better
Sweet potatoes require soil above 65 degrees F for slips to establish; 70 degrees F is ideal
Soil temperature for germination: 65-95 degrees F (optimal 80-85)
Soil thermometer note: A $10-15 soil thermometer is one of the most useful tools in vegetable gardening. Check soil temperature at a 2-inch depth in the morning (the coldest reading of the day) before planting warm-season crops. Do not rely on air temperature or calendar dates alone for soil-temperature-sensitive crops.
Step 3: Calculate Indoor Seed-Starting Dates
Count backward from the outdoor transplant date, not from the last frost date directly. These are distinct dates for most crops.
The formula: Seed start date = Transplant date minus weeks-to-transplant-size
Indoor seed-starting reference table:
Crop
Weeks Indoors Before Transplanting
Transplant Timing Relative to LFD
Notes
Onions (from seed)
10-12 weeks
4-6 weeks before LFD
Slow-growing; need early start and strong light
Celery/Celeriac
10-12 weeks
2-3 weeks before LFD
Germinates slowly at 65-70 degrees F; needs consistent moisture
Peppers
8-10 weeks
On LFD or 1-2 weeks after
Start early; peppers are slow and need warmth (75-85 degrees F soil to germinate)
Eggplant
8-10 weeks
1-2 weeks after LFD
Similar needs to pepper; chilling injury risk if transplanted cold
Spring transplants; start 6 weeks for spring, 6 weeks before fall transplant date
Cabbage
6-8 weeks
3-4 weeks before LFD
Tolerates frost; transplant early with row cover protection
Brussels Sprouts
6-8 weeks
3-4 weeks before LFD
Long season crop; must get in ground early enough to mature before fall FFD
Basil
4-6 weeks
1-2 weeks after LFD
Very frost sensitive; harden off carefully
Lettuce
4-6 weeks
4-5 weeks before LFD
Fast-germinating; transplants extend the season by several weeks
Swiss chard
4-6 weeks
2-3 weeks before LFD
Easy to start; can also direct sow
Cucumbers
3-4 weeks
1-2 weeks after LFD
Do not start too early -- roots resent disturbance and leggy starts perform poorly
Summer squash/zucchini
3-4 weeks
1-2 weeks after LFD
Grows rapidly; long-started seedlings become pot-bound and stunted
Winter squash/pumpkins
3-4 weeks
1-2 weeks after LFD
Some varieties need 100+ days; starting indoors saves critical time in short-season zones
Melons/Watermelons
3-4 weeks
2-3 weeks after LFD
Need warm soil; Zone 5 and colder benefit from transplants and black plastic mulch
Germination conditions and equipment:
Use a heat mat set to 75-80 degrees F for peppers, eggplant, tomatoes, and basil. Germination rate for peppers drops dramatically below 70 degrees F.
Use grow lights positioned 2-3 inches above seedlings for 14-16 hours per day. Insufficient light is the primary cause of leggy, weak transplants.
Thin to one seedling per cell once true leaves appear. Crowded cells produce weak root systems.
Begin fertilizing with half-strength balanced liquid fertilizer (5-5-5 or similar) once seedlings have their first set of true leaves. Seed-starting mix contains no nutrients.
Hardening off (mandatory for all transplants):
Begin 7-10 days before planned transplant date
Day 1-2: 1-2 hours outdoors in shade, no wind exposure
Day 3-4: 2-3 hours with indirect sun
Day 5-6: 4-5 hours with morning sun
Day 7-8: 6-8 hours with full sun
Day 9-10: Overnight outdoors if temps allow (above 50 degrees F for warm-season crops)
Skip hardening off or rush it, and transplant shock will set crops back 2-3 weeks -- negating the benefit of starting early
Step 4: Build the Month-by-Month Planting Calendar
Calculate every date relative to the user's confirmed LFD and FFD. Never use absolute calendar months without anchoring them to the user's specific frost dates.
Calendar construction method:
Start with LFD as the reference zero point (call it Week 0)
Count backward in weeks for cool-season crops and seed starting
Count forward in weeks for warm-season and heat-loving crops
Count backward from FFD for fall planting windows
Overlay the two sequences (spring-forward and fall-backward) to identify the full-season calendar
Direct sow semi-hardy crops outdoors; transplant brassicas with row cover
LFD minus 2 weeks
Begin hardening off warm-season transplants
LFD (Week 0)
Monitor nighttime temps; transplant tomatoes when nights stay above 50 degrees F
LFD plus 1-2 weeks
Transplant peppers, eggplant, basil; direct sow beans, corn, cucumbers, squash
LFD plus 3-4 weeks
Plant heat-lovers: melons, sweet potatoes, okra
FFD minus 10 weeks
Start fall broccoli, cauliflower, cabbage seeds indoors
FFD minus 8 weeks
Transplant fall brassicas outdoors
FFD minus 8 weeks
Direct sow fall lettuce, spinach, arugula, kale
FFD minus 6 weeks
Last direct sow of fast crops (radishes, mache, spinach)
FFD minus 3-4 weeks
Plant garlic cloves (for next year's harvest)
FFD minus 2 weeks
Cover cold-hardy fall crops with row cover for frost extension
Step 5: Design the Succession Planting Schedule
Succession planting is the practice of making multiple small plantings of a single crop at staggered intervals to extend harvest over weeks or months rather than getting a single large glut. It is most valuable for crops that mature quickly, bolt in heat, or degrade rapidly after harvest.
How to calculate succession intervals:
Divide the total planting window by the days-to-maturity
For leaf crops: replant when the previous sowing reaches 4-6 inches tall (about 2-3 weeks after germination in spring)
For root crops and beans: replant when the previous sowing is clearly established (2-3 weeks after germination)
Stop succession planting with enough days remaining before the crop's limiting factor (heat bolting for cool-season crops, fall frost for warm-season crops)
Succession planting reference guide:
Crop
Days to Harvest
Succession Interval
Spring Window
Summer Window
Fall Window
Notes
Radishes
22-30 days
Every 10-14 days
LFD -6 to LFD -2
Avoid peak heat
FFD -8 to FFD -4
Skip planting in soil above 80 degrees F
Leaf lettuce
30-45 days
Every 2-3 weeks
LFD -6 to LFD +2
Shade extends window
FFD -8 to FFD -4
Switch to heat-tolerant varieties (Jericho, Nevada) in summer
Spinach
35-50 days
Every 2-3 weeks
LFD -6 to LFD -1
Bolts; avoid
FFD -8 to FFD -4
Bolts in day length over 14 hours; fall planting is more reliable
Bush beans
50-60 days
Every 2-3 weeks
LFD to LFD +2
LFD +4 to FFD -10
--
Stop planting 60 days before FFD to ensure harvest
Arugula
25-40 days
Every 2 weeks
LFD -5 to LFD
Bolts quickly
FFD -7 to FFD -3
Bolts and turns bitter above 75 degrees F
Cilantro
45-70 days (to seed)
Every 2-3 weeks
LFD -3 to LFD +1
Limited; use shade
FFD -8 to FFD -4
Slow-bolt varieties (Leisure, Santo) extend spring window
Dill
40-60 days
Every 3 weeks
LFD -2 to LFD +3
Limited
FFD -8
Self-seeds prolifically; allow some to bolt for natural succession
Peas (shell/snap)
60-75 days
One or two plantings
LFD -6 to LFD -4
Cannot tolerate summer heat
FFD -10 to FFD -8
Short planting window; fall planting needs at least 70 days before FFD
Scallions/Green onions
50-70 days
Every 3 weeks
LFD -5 to LFD
Yes
FFD -10
Slow germination; can direct sow or transplant
Kale
50-70 days (to harvest)
One or two plantings
LFD -6
--
FFD -8
Fall kale sweeter; frost improves flavor by converting starches to sugars
Step 6: Add Season-Extension Strategies
Season extension tools are often the difference between a 140-day growing season and an effective 180-day season. Include recommendations calibrated to the user's zone and stated goals.
Row covers (Reemay or spunbond fabric):
Lightweight (0.5 oz/sq yard): provides 2-4 degrees F of frost protection; allows 85-90% light transmission; extends season by 2-3 weeks
Medium weight (1.5 oz/sq yard): provides 4-6 degrees F of frost protection; 70% light transmission; extends season by 3-5 weeks
Heavy weight (2.0+ oz/sq yard): provides 6-10 degrees F of frost protection; reduces light significantly; primarily used for hard freeze protection, not active growing
Lay directly on crops or use wire hoops to keep fabric off foliage; anchor edges with soil, sandbags, or landscape staples
Cold frames:
Typically a bottomless box with a transparent lid (old storm windows, corrugated polycarbonate, or twin-wall polycarbonate)
Adds 4-8 weeks to both ends of the season depending on construction and location
Vent on warm days (above 40 degrees F outside) to prevent overheating; unvented cold frames can exceed 90 degrees F on sunny winter days
Orient south-facing for maximum solar gain
Black plastic mulch:
Raises soil temperature by 5-10 degrees F; critical for warm-season crops in Zone 5 and colder
Particularly useful for peppers, melons, eggplant, and sweet potatoes where soil temperature is the limiting factor
Lay 1-2 weeks before transplanting to pre-warm the soil
Wall-O-Waters and season starters:
Allow tomato transplants 3-4 weeks earlier than normal -- up to 6 weeks before LFD in Zone 5-6
Fill outer cells with water; thermal mass absorbs daytime heat and releases it overnight
Plants inside can withstand nights down to 16-20 degrees F when properly filled
Step 7: Format and Deliver the Calendar
Assemble all data into the output format below. Include:
A header with confirmed zone, LFD, and FFD
An indoor seed-starting table sorted chronologically
Spring planting table with direct sow vs. transplant column
A succession planting schedule for all applicable crops
Fall planting table counting backward from FFD
A monthly at-a-glance summary for quick reference
Any zone-specific notes or season-extension recommendations
Output Format
## Planting Calendar: Zone [X] (LFD: [Month Day], FFD: [Month Day], Growing Season: ~[N] days)
> **Important:** All dates are calculated from LFD = [date] and FFD = [date].
> Verify your local frost dates at your county cooperative extension or NOAA's
> climate data portal. Microclimates can shift these dates by 1-3 weeks.
---
### Indoor Seed Starting
| Start Date | Crop | Variety Notes | Weeks Indoors | Transplant Date | Germination Temp |
|------------|------|---------------|---------------|-----------------|-----------------|
| [Date] | [Crop] | [e.g., determinate tomato for short seasons] | [N] weeks | [Date] | [N] degrees F |
---
### Spring Outdoor Planting
| Date Range | Crop | Method | Soil Temp Required | Notes |
|------------|------|--------|--------------------|-------|
| [Date range] | [Crop] | Direct sow / Transplant | [N] degrees F | [Specific note] |
---
### Succession Planting Schedule
| Crop | First Planting | Replant Every | Last Planting Date | # of Plantings | Bolting / Stop Trigger |
|------|---------------|---------------|--------------------|---------------|----------------------|
| [Crop] | [Date] | [N] weeks | [Date] | [N] | [Heat bolt / FFD -N weeks] |
---
### Summer Maintenance Calendar
| Date Range | Action | Purpose |
|------------|--------|---------|
| [Date] | [Task] | [Why it matters] |
---
### Fall Planting Calendar (Counting Backward from FFD: [date])
| Plant By Date | Crop | Days to Maturity | Method | Notes |
|--------------|------|-----------------|--------|-------|
| [Date] | [Crop] | [N] days | Direct sow / Transplant | [Note] |
---
### Season Extension Options
| Tool | Protection Level | Effective Date Shift | Best Used For |
|------|-----------------|---------------------|---------------|
| Row cover (lightweight) | +3-4 degrees F | +2-3 weeks | Cool-season crops, frost protection |
| Row cover (medium) | +5-6 degrees F | +3-4 weeks | Brassicas, fall extension |
| Cold frame | +4-8 degrees F | +4-6 weeks | Starting/ending season |
| Black plastic mulch | Soil +8-10 degrees F | Enables earlier transplant | Tomatoes, peppers, melons |
| Wall-O-Waters | Down to 16-20 degrees F | +3-6 weeks (spring) | Tomatoes only |
---
### Monthly At-a-Glance
| Month | Priority Actions | What to Watch For |
|-------|-----------------|------------------|
| [Month] | [1-3 key tasks] | [Timing trigger or risk] |
---
### Crop-Specific Notes
[Any additional notes about specific varieties, regional considerations,
soil temperature warnings, or timing nuances for the crops requested]
Rules
Always anchor to frost dates, never to calendar months alone. A Zone 4 gardener and a Zone 8 gardener follow the same sequence of steps but months apart. Presenting dates without the zone and frost date context they derive from will cause real planting failures.
Distinguish between soil temperature and air temperature for every warm-season crop. Soil temperature lags air temperature by 2-4 weeks in spring. A warm April week does not mean the soil at 2-inch depth has crossed 60 degrees F. This is the most common cause of poor germination and transplant shock in spring.
Always specify direct sow vs. transplant for every crop. Cucumbers, squash, beans, corn, peas, and root crops do best from direct sow and resent root disturbance. Starting them indoors longer than 3-4 weeks will produce root-bound, stunted transplants that underperform direct-sown seedlings.
Include hardening off time in all transplant date calculations. If the transplant target date is May 10, the hardening off window starts May 1-3. Failing to account for this means transplants hit the garden without acclimatization and suffer a 2-3 week setback.
Never omit the fall planting calendar. Fall is the most overlooked and often most productive season for cool-season crops. Kale, spinach, lettuce, broccoli, and carrots planted in late summer produce harvests through October or November in most zones. Presenting only a spring calendar is an incomplete service.
Flag bolting risk for all cool-season crops. Spinach, cilantro, arugula, and lettuce bolt (go to seed) when day length exceeds 14 hours and temperatures regularly exceed 80 degrees F. Include the expected bolting window and recommend heat-tolerant varieties or shade cloth for summer succession.
Specify days-to-maturity when recommending varieties for short-season zones. In Zone 3-4, the difference between an 85-day tomato and a 70-day tomato can mean the difference between a full harvest and a crop killed by early frost. Always recommend short-season varieties (65-75 day tomatoes, 65-day cucumbers, etc.) for zones with growing seasons under 130 days.
Do not present frost dates as exact. They are 30-year statistical averages with a 50% probability of frost on that date. There is a 10% probability of frost up to 2-3 weeks after the "last frost date." For frost-sensitive crops like basil, peppers, and transplanted tomatoes, recommend using season-extension tools or waiting for more reliable warmth rather than transplanting exactly on the LFD.
Flag the soil workability constraint for early spring direct sowing. Many gardeners in Zones 4-5 can technically sow peas or spinach 6 weeks before LFD by the calendar, but late snow, frozen ground, or saturated soil makes this impossible. Include a note that soil must be friable (crumbles rather than smears when squeezed) before any direct sowing.
Include garlic planting timing in every calendar for Zone 5 and colder. Fall-planted hardneck garlic is one of the most rewarding crops a gardener in a cold climate can grow, and most novice gardeners do not know about it. Plant cloves 4-6 weeks before hard freeze (FFD minus 3-5 weeks) at 2-3 inches deep with 6 inches of straw mulch on top. Harvest the following July when lower leaves begin to yellow.
Edge Cases
Zone 3-4 (Under 120-Day Growing Season): The Short-Season Override
The standard timing tables do not work without modification for Zone 3b and colder. Apply these adjustments:
Nearly everything except radishes, peas, and direct-sown spinach should be started indoors
Wall-O-Waters allow tomato transplants in Zone 4 as early as late April -- 5-6 weeks before the LFD
High tunnels (unheated plastic-covered structures) effectively shift a Zone 4 garden to Zone 6 conditions inside
Avoid warm-season crops with days-to-maturity exceeding 85 days unless using season extension tools; melons and sweet potatoes are marginal without black plastic mulch and row cover
Fall planting window is very narrow (FFD minus 6 weeks maximum); prioritize kale, spinach, and radishes, which are the most frost-tolerant
Zone 9-10 (Frost-Rare or Frost-Free): Inverse Season Planning
The frost-date framework must be entirely replaced with a cool season/warm season framework:
Cool season (October-March): This is peak growing season. Plant all brassicas, lettuces, root vegetables, peas, cilantro, and parsley during this window. These crops fail in summer heat regardless of zone.
Warm season (March-October): Tomatoes, peppers, cucumbers, squash, and beans are planted in late winter (February-March) and harvested by June-July before the most intense heat arrives. A second planting in August-September for fall harvest is common.
Summer temperatures in Zone 9-10 are the primary limiting factor, not frost. Many crops go dormant, bolt, or develop fungal disease under prolonged summer heat and humidity.
Provide a bimodal calendar with two peak planting seasons rather than the spring-summer-fall linear structure.
Garlic should be planted in November-December; pre-chill garlic cloves in the refrigerator for 4-6 weeks before planting in very warm zones (9b, 10) to simulate the cold stratification they require.
Mid-Season Start (User Missed the Spring Window): Rapid Reassessment
If a user contacts you in June, July, or August having missed the spring planting window, reframe the conversation around what is still achievable:
Calculate remaining growing days to FFD
If 90+ days remain: direct sow beans, cucumbers, summer squash, and fast-maturing tomato varieties (but transplants only if available; starting tomatoes from seed in June will not produce before frost in Zone 5 or colder)
If 70-90 days remain: focus on fall crops -- plant lettuce, kale, arugula, broccoli transplants, and radishes for fall harvests
If 50-70 days remain: spinach, arugula, lettuce, and radishes are the only viable crops; plant immediately
Frame the response positively: "You have a great fall garden window" rather than "you missed spring"
Provide the succession planting table starting from the current date, truncated to what fits the remaining season
Raised Beds vs. In-Ground Gardens: Soil Temperature Difference
Raised beds warm 2-4 weeks faster than in-ground soil in spring and cool 2-4 weeks faster in fall. This shifts the planting calendar meaningfully:
In Zones 5-6, raised bed gardeners can often transplant tomatoes and peppers 1-2 weeks earlier than in-ground gardeners in the same location
Raised beds are more vulnerable to early fall frost because the soil has less thermal mass
Recommend black plastic mulch for in-ground warm-season crops in Zones 4-5; it is less necessary in raised beds where the soil warms faster
Container and Balcony Gardens: Modified Timing
Container gardeners face unique constraints that alter the standard timing:
Containers dry out rapidly and can freeze solid in winter, killing roots -- this matters for container-grown perennial herbs (thyme, sage, rosemary)
Small containers (under 5 gallons) have very little thermal mass and experience more extreme temperature swings than in-ground soil
Tomatoes need a minimum 5-gallon container (10-15 gallon preferred for full-size varieties); underpotted tomatoes stall in growth regardless of planting timing
Succession planting works especially well in containers because spent crops can be removed and replaced individually without disturbing adjacent plantings
Lightweight row cover draped over container plants on frost nights provides adequate protection without permanent infrastructure
Regional Anomalies: Fog, Coastal, and High Altitude Zones
USDA zones are based solely on minimum winter temperature. They do not account for:
Pacific Coast marine climates (Zone 9-10 coastal California): Summer temperatures are cool (55-65 degrees F highs), which is too cold for tomatoes and peppers to set fruit well despite the frost-free classification. Warm-season crops must be timed to the inland heat, or cold-tolerant varieties ("Stupice," "Legend") must be used.
High elevation Zone 5 (Colorado Front Range, Intermountain West): Strong UV radiation accelerates plant growth but afternoon thunderstorms can cause hail damage. Short-season varieties are mandatory. Plant in sheltered locations and be prepared for late spring snowstorms even after LFD.
Gulf Coast Zone 8-9: High summer humidity drives fungal disease pressure. Timing tomatoes to finish production before June heat and humidity is critical. Consider planting tomatoes in February-March (as transplants from fall-started seeds) for a spring-only harvest cycle.
User Has No Zone Information: Estimation from City or Region
If the user cannot identify their USDA zone or does not know their frost dates:
Ask for their nearest large city or general region (e.g., "suburban Chicago" or "central Virginia")
Provide an estimated zone with the caveat that this is approximate
Recommend they confirm with their state's cooperative extension service
Chicago area: Zone 5b-6a, LFD around April 25 - May 5, FFD around October 15-25
Atlanta area: Zone 7b-8a, LFD around March 5-15, FFD around November 15-25
Denver area: Zone 5b-6a but with significant microclimate variation, LFD May 1-15
Seattle area: Zone 8b, LFD March 1-15 but cool summers limit heat-loving crops
Houston area: Zone 9a, LFD January 20 - February 10; summer heat stops warm-season crops by June
Do not build a detailed calendar until frost dates are confirmed -- flag this explicitly
Example
Input: "I'm in Zone 6a, last frost around April 10, first fall frost around November 1. I want to grow tomatoes (2 varieties), peppers, lettuce, basil, cilantro, and zucchini. This is a raised bed garden. What's my full-season planting calendar?"
Output:
Planting Calendar: Zone 6a (LFD: April 10, FFD: November 1, Growing Season: ~205 days)
Important: All dates are calculated from LFD = April 10 and FFD = November 1. Verify your local frost dates at your county cooperative extension service. As a raised bed garden, your soil will warm 2-3 weeks faster than in-ground plots -- you can often transplant tomatoes and peppers 1 week earlier than Zone 6a in-ground gardeners. A 50% frost probability exists on April 10; for best results transplant warm-season crops when nighttime lows are consistently above 50 degrees F (typically April 15-20 in your zone).
Indoor Seed Starting
Start Date
Crop
Variety Notes
Weeks Indoors
Transplant Date
Germination Temp
Jan 13
Peppers
Choose 1 sweet bell and 1 frying/snack type (faster maturing than bells)
10-12 weeks
April 20-28
78-85 degrees F; use heat mat
Feb 3
Tomatoes
Choose 1 indeterminate slicer (75-80 days) and 1 determinate paste or cherry (65-70 days) for extended harvest
8-10 weeks
April 18-25
70-75 degrees F
Feb 10
Eggplant (optional add-on)
If desired -- same timeline as pepper
8-10 weeks
April 20-28
78-85 degrees F; heat mat
March 10
Basil
Genovese or Italian Large Leaf; very frost sensitive
4-6 weeks
April 22-30
70-75 degrees F
March 15
Lettuce transplants
Oakleaf, Buttercrunch, or Jericho (heat-tolerant for extended spring window)
4 weeks
April 1-8
60-65 degrees F; cool germination
Spring Outdoor Planting
Date Range
Crop
Method
Soil Temp Required
Notes
March 1-10
Lettuce (seed)
Direct sow 1/8 inch deep
45 degrees F (germinates down to 40)
Sow thinly; thin to 6 inches for leaf types; raised bed soil may be workable early March
March 1-10
Cilantro (first succession)
Direct sow 1/4 inch deep, 3 inches apart
50 degrees F
Bolt-resistant varieties: Leisure, Santo; this planting will bolt by late May
March 10-20
Spinach
Direct sow 1/2 inch deep, 3 inches apart
40 degrees F
Spring spinach is short-lived; expect 4-6 harvests before bolting in late May
March 20-April 1
Arugula
Direct sow thinly
40 degrees F
Cut-and-come-again; bolts when temps exceed 75 degrees F consistently
April 1-10
Lettuce transplants (from indoor starts)
Transplant to 8-inch spacing
45 degrees F
From March 15 starts; plant out 1 week before LFD; cover with lightweight row cover if frost threatens
April 1-10
Peas (snap or shell)
Direct sow 1 inch deep, 2 inches apart
45 degrees F
This is late for Zone 6a spring peas; plant as soon as possible for harvest before summer heat arrives
April 10
Begin monitoring overnight temperatures for transplant window
--
--
Wait until 3+ consecutive nights above 50 degrees F before transplanting tomatoes; peppers prefer 55 degrees F nights
April 18-25
Tomatoes
Transplant (from Feb 3 starts)
60 degrees F at 2-inch depth
Raised bed soil should reach 60 degrees F by mid-April; confirm with soil thermometer before planting
April 20-28
Peppers
Transplant (from Jan 13 starts)
65 degrees F at 2-inch depth
Peppers suffer chilling injury below 55 degrees F; raised beds warm faster than in-ground, but verify soil temp
April 22-30
Basil
Transplant (from March 10 starts)
60 degrees F
Basil dies at 32 degrees F and is damaged at prolonged temps below 50 degrees F; harden thoroughly
April 25 - May 1
Zucchini
Direct sow OR transplant from 3-week-old starts
65 degrees F
Sow 2 seeds per hill, 1 inch deep; thin to 1 plant when 4 inches tall; raised beds will have adequate soil temp by late April
May 1-10
Cilantro (second succession)
Direct sow
55 degrees F
Partial shade will extend this planting's life into June; expect bolting by mid-June
Hardening off schedule: Begin hardening off tomatoes, peppers, and basil starting April 8-10.
April 8-10: 1-2 hours outdoor shade only
April 11-14: 3-4 hours indirect/morning sun
April 15-18: Full day outdoors, bring in if frost forecast
April 18-20: Overnight outdoors if nights above 50 degrees F (tomatoes); nights above 55 degrees F (peppers, basil)
April 18-25: Transplant tomatoes; April 20-28: Transplant peppers and basil
Succession Planting Schedule
Crop
First Planting
Replant Every
Last Planting Date
# of Plantings
Bolting / Stop Trigger
Lettuce (leaf)
March 1
2-3 weeks
Aug 15
7-8 total
Spring bolt when temps exceed 80 degrees F; use Jericho or Nevada varieties for summer plantings; direct sow summer in light shade
Arugula
March 1
2 weeks
Sept 1
8-9 total
Bolts when temps consistently exceed 75 degrees F; summer succession in shade only
Cilantro
March 1
2-3 weeks
Sept 15
7-8 total
Spring successions bolt by mid-May; resumeplanting in mid-August for productive fall window
Zucchini
April 25
Not needed (plant only 1-2 plants)
--
1-2 plants total
1 zucchini plant is usually sufficient; succession not needed; plants become powdery mildew-prone by August in Zone 6 -- second succession planting in late June extends fresh production
Basil
April 22
Can start second round indoors June 1 for fresh late-summer plant
July 1 transplant
2 generations
Basil peaks and then declines after first flowering; pinch flowers constantly; replace plant in July for vigorous late-summer harvest
Cilantro summer gap strategy: Cilantro bolts too quickly for productive summer harvests in Zone 6 heat. Skip succession plantings from approximately June 15 to August 1. Resume planting in mid-August for a productive fall window (August-October). The fall cilantro crop in Zone 6 is often the best of the year.
Summer Maintenance Calendar
Date Range
Action
Purpose
Late May - June
Mulch tomatoes and peppers with 3-inch layer of straw or wood chips after soil reaches 70 degrees F
Retain moisture, suppress weeds, prevent soil splash on lower leaves (reduces early blight)
June
Pinch basil flower buds as soon as they appear weekly
Delays bolting by 4-6 weeks and maintains leaf production
June 15 - July 1
Stop cool-season succession plantings (arugula, spring cilantro window closes)
Prevent wasted effort on crops that will bolt immediately
June 15
Begin supporting tomatoes: cage, stake, or trellis all plants; remove any suckers from indeterminate varieties if using single-stake method
Unsupported indeterminate tomatoes become unmanageable by July
July 1-10
Start second-generation basil indoors or purchase transplant for mid-July installation
Replaces the spring basil plant which begins declining after repeated flowering
July 10-20
Start fall broccoli and cauliflower seeds indoors for August transplant (if adding to plan)
Requires 6-7 weeks indoors; transplants go out FFD minus 10 weeks = ~Aug 20
July 15 - Aug 1
Begin succession-planting lettuce again after summer peak heat
Direct sow in partial shade (east-facing bed side, under taller crops) for fall harvest
July 20
Evaluate zucchini for powdery mildew; consider replacing with second planting if first plant is declining
Zone 6 late July heat and humidity creates prime conditions for powdery mildew
Aug 1-15
Restart cilantro successions in earnest for fall harvest
Prime fall cilantro window begins; weather cools and bolting slows dramatically
Aug 1-15
Direct sow spinach, arugula, lettuce for fall harvest
Count back 50 days from FFD (Nov 1) plus 14-day buffer for slowed autumn growth = plant by Aug 10-20
Fall Planting Calendar (Counting Backward from FFD: November 1)
Plant By Date
Crop
Days to Maturity
Method
Notes
Aug 10
Spinach
35-45 days
Direct sow 1/2 inch deep
Fall spinach is excellent in Zone 6; frost improves sweetness; overwintered spinach may survive under row cover
Aug 10-20
Lettuce (leaf)
30-45 days
Direct sow or transplant
Plant heat-tolerant varieties in August heat (Jericho, Nevada); switch to Buttercrunch and Oakleaf in September
Aug 15-20
Arugula
30-40 days
Direct sow thinly
Fall arugula is ideal -- no bolting risk in cooling temps; peppery flavor intensifies with cool nights
Aug 20-30
Kale (fall planting)
50-60 days
Transplant from late-July indoor starts OR direct sow
Kale is at its best in fall; light frost (28-30 degrees F) converts starches to sugars; flavor peaks in October-November
Aug 20 - Sept 1
Radishes
25-28 days
Direct sow 1/2 inch deep, 2 inches apart
3-4 succession plantings possible in fall window; radishes are one of the easiest crops for September production
Sept 1-10
Cilantro (final fall successions)
45-70 days to leaf harvest
Direct sow thickly
This window produces the best cilantro of the year in Zone 6; harvest leaves until hard freeze
Sept 15 - Oct 1
Garlic (hardneck)
Overwinter (harvest July next year)
Plant cloves 2-3 inches deep, 6 inches apart
Choose Rocambole or Porcelain types for Zone 6; mulch with 6 inches of straw after planting; remove scapes in June
Oct 1-10
Cover fall crops with row cover (medium weight)
--
Drape over wire hoops
Extends harvest 3-4 weeks past first frost; lettuce, spinach, and kale survive to late November in Zone 6 with protection
Season Extension Options
Tool
Protection Level
Effective Date Shift
Best Used For
Lightweight row cover (0.5 oz)
+2-4 degrees F
+2-3 weeks
Early spring lettuce, fall harvest extension for cool-season crops
Medium row cover (1.5 oz)
+4-6 degrees F
+3-4 weeks
Fall kale/spinach/arugula through November
Wall-O-Waters
Down to 18 degrees F overnight
+3-5 weeks for tomatoes
Spring tomato transplants; remove when temps stabilize above 60 degrees F nights
Black plastic mulch
Soil +8-10 degrees F
Enables 1-2 weeks earlier transplant
Tomatoes, peppers in Zone 6 raised beds -- less critical but useful for peppers
Cold frame
+4-8 degrees F
+5-7 weeks total
Overwinter spinach and mache; start spring lettuce in January-February
Raised bed specific note: Your raised beds should reach 60 degrees F soil temperature approximately April 12-15, roughly 5-7 days earlier than in-ground soil in the same location. You can likely transplant tomatoes a week earlier than Zone 6a in-ground averages suggest. Use a soil thermometer to confirm before planting.
Monthly At-a-Glance
Month
Priority Actions
What to Watch For
January
Start pepper seeds indoors under grow lights (Jan 13); set up heat mat at 80 degrees F
Leggy seedlings indicate insufficient light; raise lights or add more hours
February
Start tomato seeds Feb 3 (8-9 weeks before LFD)
Check for damping off (stem rot at soil line); ensure good airflow around seedlings