seasonal-planting-calendar

# Seasonal Planting Calendar ## When to Use **Use this skill when:** - A user asks when to plant a specific vegetable, herb, or flower and mentions their location, ZIP code, or USDA zone - A user wants a complete planting schedule for an upcoming season and needs it anchored to their actual frost dates - A user asks when to start seeds indoors and wants specific dates relative to transplanting outdoors - 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 - Examples: kale, spinach, turnips, kohlrabi, mache, claytonia, arugula, overwintered onions - Fall planting is often more productive than spring for these crops -- bolting is not a risk in cooling fall temperatures - Soil temperature for germination: 40-85 degrees F (optimal 60-65) **Category 2 -- Semi-hardy cool-season crops (survive light frost to 28-30 degrees F, thrive 45-75 degrees F):** - Direct sow 2-4 weeks before LFD; transplant 3-5 weeks before LFD with some frost protection - Examples: lettuce, peas, Swiss chard, beets, carrots, parsnips, broccoli, cauliflower, cabbage, Brussels sprouts, cilantro, dill, parsley - Soil temperature for germination: 45-85 degrees F (optimal 65-70) **Category 3 -- Tender warm-season crops (killed by frost, need soil above 60 degrees F, prefer air temperatures 65-85 degrees F):** - Transplant outdoors at or 1-2 weeks after LFD when nighttime lows consistently exceed 50 degrees F - Direct sow 1-2 weeks after LFD when soil temperature at 2-inch depth exceeds 60 degrees F - Examples: tomatoes, cucumbers, summer squash, zucchini, beans (pole and bush), basil, corn, tomatillos - Soil temperature for germination: 60-95 degrees F (optimal 70-85) **Category 4 -- Heat-loving crops (stunted or fail below 65 degrees F soil, thrive in 80-95 degree F air temperatures):** - Plant 2-4 weeks after LFD, not before - Examples: peppers, eggplant, sweet potatoes, melons, watermelon, okra, lima beans, southern peas, lemongrass, ginger - 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 | | Leeks | 8-10 weeks | 4 weeks before LFD | Start same time as onions; slow establishment | | Tomatoes | 6-8 weeks | On LFD or 1 week after | 8 weeks produces stocky transplants; avoid leggy seedlings | | Broccoli/Cauliflower | 6-8 weeks | 3-4 weeks before LFD | 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 **Key timing anchors:** | Timing | Action | |--------|--------| | LFD minus 12 weeks | Start onion, celery, leek seeds indoors | | LFD minus 10 weeks | Start pepper and eggplant seeds indoors | | LFD minus 8 weeks | Start tomato, broccoli, cabbage seeds indoors | | LFD minus 6 weeks | Start lettuce, chard transplants indoors; direct sow hardy cool-season crops outdoors | | LFD minus 4 weeks | 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 |