Garden Calendar Planner

Region{{ resultsReady ? computation.normalizedInputs.zone : '—' }} Frost-free span{{ resultsReady ? `${computation.values.frost_free_days} days` : '—' }} Succession{{ resultsReady ? successionBadge : '—' }}

Climate zone or region:

Examples: USDA 8b, coastal allotment, or north garden.

Planning season:

Choose the season that best describes the work you are organizing.

Plan start date:

Earlier crop checkpoints stay visible and are marked as before the plan window.

Average last spring frost:

Use a local long-term average, then watch current soil and weather conditions.

Average first fall frost:

The fall frost must be later than the spring frost.

Plan emphasis:

All artifacts remain available; this changes the planning emphasis, not the crop constants.

Planning horizon:

Choose 4 to 24 whole weeks.

weeks

Succession interval:

Fourteen days is a common starting point for quick crops.

days

Succession waves:

Long-season crops remain visible but are marked as weak repeat-sowing candidates.

waves

Crops:

Known crops use local planning profiles; unmatched names use a clearly labelled generic profile.

Bed notes:

Examples: Bed A · morning sun; Bed B · drip irrigation.

Extra fall safety buffer:

The neutral default is 0 days. Add a buffer for conservative fall planning.

days

Planning season{{ resultsReady ? seasonDisplay : '—' }}

Spring frost anchor{{ resultsReady ? formatDate(computation.normalizedInputs.last_spring_frost) : '—' }}

Fall frost anchor{{ resultsReady ? formatDate(computation.normalizedInputs.first_fall_frost) : '—' }}

Plan emphasis{{ resultsReady ? emphasisDisplay : '—' }}

Date	Crop	Action	Bed	Window	Planning note	Copy
{{ formatDate(row.date) }}	{{ row.crop }}	{{ row.action }}	{{ row.bed }}	{{ row.period }}	{{ row.note }}

Crop	Start method	Indoor start	Harden off	Plant outdoors	Last feasible sow	Profile	Copy
{{ row.crop }}	{{ row.method }}	{{ formatOptionalDate(row.indoor_start) }}	{{ formatOptionalDate(row.harden_start) }}	{{ row.plant_outdoors }}	{{ formatDate(row.last_feasible_sow) }}	{{ row.profile_note }}

Crop	Wave	Sow/start	Plant outdoors	Harvest window	Fall cutoff	Feasibility	Copy
{{ row.crop }}	{{ row.wave }}	{{ formatDate(row.sow_date) }}	{{ formatDate(row.plant_date) }}	{{ formatDateRange(row.harvest_start, row.harvest_end) }}	{{ formatDate(row.last_feasible_sow) }}	{{ row.feasibility }}

Crop	Bed slot	First outdoor date	Season task	Rotation note	Copy
{{ row.crop }}	{{ row.bed }}	{{ formatDate(row.first_outdoor_date) }}	{{ row.season_task }}	{{ row.rotation_note }}

Due date	Crop	Focus	Cadence	Action	Copy
{{ formatDate(row.date) }}	{{ row.crop }}	{{ row.focus }}	{{ row.cadence }}	{{ row.action }}

A vegetable calendar connects three clocks that rarely agree perfectly: the local frost season, the crop’s development time, and the gardener’s available weeks. A seed packet may say “55 days,” but that number does not account for the time spent raising a transplant, cool soil, heat, cultivar differences, or a late start.

Average frost dates are planning anchors, not guaranteed safe dates. The last spring frost marks a typical end to freezing conditions, and the first fall frost marks a typical return. Their difference is the expected growing season between frosts. Actual frost can arrive on either side of those averages, while protected beds and local microclimates may shift what is practical.

Indoor start: The date seed is started under protection before transplanting outdoors.
Direct sow: The date seed is placed in its final outdoor bed.
Hardening off: A gradual adjustment period before indoor-grown plants move outside.
Succession planting: Repeated small sowings or replacement crops used to extend harvest rather than planting everything at once.

Cool-season vegetables such as spinach, peas, and lettuce can often begin before the last spring frost. Tender crops such as basil, beans, cucumbers, and tomatoes normally need warmer conditions. The planting method matters too: a tomato’s indoor-start date may be weeks before its outdoor date, while a radish schedule begins with direct sowing.

Repeated sowings work best for crops with short maturity times and limited harvest windows. Long-season fruiting crops may remain productive from one planting, so extra waves can consume space without adding useful harvest. The final sowing also needs enough time to establish and mature before the first fall frost, plus a crop-specific margin.

Calendar dates should be checked against the seed packet, soil temperature, current forecast, and local Extension guidance. A dated plan organizes work; it cannot predict germination, yield, pests, or the exact day a crop will mature.

How to Use This Tool:

Begin with local long-term frost averages, then describe the crops and time window you actually intend to manage.

Enter a Climate zone or region, Plan start date, Average last spring frost, and Average first fall frost. The fall date must be later than the spring date.
Choose a 4–24 week Planning horizon and the plan emphasis. The emphasis changes which part deserves attention; it does not change crop constants or remove other results.
Add one crop per line, up to 12. Known crop names use specific planning profiles; an unmatched name remains in the plan with a clearly marked generic profile.
Set the Succession interval, number of waves, and any Extra fall safety buffer. Use bed notes when you want crop rows assigned across named beds.
Review the dated rows and warnings. Move or remove waves marked past the fall cutoff, then compare every important date with local conditions and cultivar instructions.

Interpreting Results:

The most useful distinction is whether a task falls before the plan start, inside the selected week range, or beyond it. Earlier checkpoints are not errors: they show work that should already have happened or dates that may need to be revised.

A succession row marked Within fall cutoff has a sow date on or before the calculated final feasible date. Past fall cutoff means the entered frost assumptions and crop profile do not leave the modeled maturity margin.
Weekly workload counts summarize generated preparation, planting, establishment, and harvest-opening tasks. They indicate calendar congestion, not labor hours.
A generic-profile warning means the crop name did not match a local profile. Verify its start method, maturity days, and frost tolerance before acting on the date.
Harvest dates are estimates. Use plant condition and cultivar-specific maturity signs rather than treating the calendar as a guarantee.

Technical Details:

The schedule is built with civil calendar-day arithmetic, so every result is a date rather than an elapsed-hour timestamp. Each crop name selects a stored profile containing its start method, indoor lead, outdoor offset from spring frost, maturity time, harvest window, succession suitability, and fall buffer.

Formula Core

The visible planning window converts whole weeks to days and includes both its first and last date:

H = 7 W, D_{end} = D_{start} + H - 1

W is the 4–24 week horizon. Days between the average frost dates equal first fall frost minus last spring frost; the boundary dates themselves are not both added to that difference.

For a direct-sown crop, the final feasible sow date subtracts maturity, the crop’s frost buffer, and the optional extra safety buffer from the first fall frost. An indoor-started crop also subtracts its indoor lead:

D_{last} = D_{fall} - (M + B + S + L)

M is maturity days, B is the crop-profile frost buffer, S is the selected 0–28 day extra buffer, and L is indoor weeks multiplied by seven for the transplant path or zero for direct sowing.

Lookup Core

Stored profiles cover tomato, basil, lettuce, broccoli, cabbage, cauliflower, kale, spinach, Swiss chard, radish, carrot, beet, pea, bean, cucumber, summer and winter squash, melon, pepper, eggplant, onion, and corn. The table shows representative profile differences rather than every row.

Representative vegetable crop planning profiles
Crop	Method	Outdoor offset from spring frost	Maturity	Fall buffer	Repeat sowing
Spinach	Direct	−35 days	40 days	0 days	Suitable
Lettuce	Either	−28 days direct	45 days	7 days	Suitable
Tomato	Indoor, 7 weeks	+10 days	75 days	14 days	Weak fit
Bean	Direct	+7 days	55 days	14 days	Suitable
Generic crop	Either, 6 weeks	+14 days	65 days	14 days	Assumed suitable

Rule Core

The first wave begins on the later of the plan start and the profile’s recommended sow date. Every later wave adds the chosen 7–45 day interval. A wave is inside the fall cutoff when its sow date is less than or equal to the final feasible sow date; equality is accepted. Indoor profiles add their indoor lead again to find the outdoor planting date.

Preparation is scheduled seven days before outdoor planting. Establishment checks occur seven days after the first planting, and the harvest window opens at planting plus maturity days. Events outside the chosen horizon remain in the dated plan but do not add to the weekly workload chart.

Accuracy Notes:

The crop profiles are planning heuristics, not local forecasts or cultivar guarantees. Before using a date, check:

the seed packet’s start method and days-to-maturity basis;
local frost probability, soil temperature, and the current forecast;
protection such as row cover, greenhouse space, or a warm microclimate; and
whether heat, daylight, pests, or slow establishment could delay maturity.

Worked Examples:

Four lettuce sowings

With a 14-day interval, four lettuce waves are spaced six weeks from the first sow date to the last. Each row is still checked against the calculated fall cutoff, so a late fourth wave can be marked past the cutoff even though the earlier three remain usable.

An unmatched cultivar name

A crop line that does not match the stored names uses the generic 65-day profile, six-week indoor lead, and 14-day frost buffer. Keep the generated row as a placeholder, then replace its dates with cultivar and local guidance rather than treating the generic result as verified.

References:

When to Plant Vegetables, University of Maryland Extension, updated August 3, 2026.
Vegetable Succession and Companion Planting, University of Maryland Extension, updated July 30, 2026.
Planting the Vegetable Garden, University of Minnesota Extension.