Use our free Grow a Garden Calculator to plan your perfect garden with comprehensive tools. Calculate garden size, plant spacing, soil needed, watering requirements, and harvest yields — all in one place.
| Plant | Spacing | Row Spacing | Days to Harvest | Avg Yield/Plant |
|---|---|---|---|---|
| 🍅 Tomatoes | 18-24" | 36-48" | 60-85 | 10-15 lbs |
| 🌶️ Peppers | 12-18" | 18-24" | 60-90 | 5-10 lbs |
| 🥒 Cucumbers | 12" | 36-60" | 50-70 | 10 lbs |
| 🥬 Lettuce | 6-12" | 12-18" | 45-55 | 0.5 lbs |
| 🥕 Carrots | 2-4" | 12-18" | 70-80 | 0.5 lbs |
| 🥔 Potatoes | 10-12" | 30-36" | 90-120 | 5-10 lbs |
| 🧅 Onions | 4-6" | 12-18" | 100-175 | 0.5-1 lbs |
| 🌽 Corn | 8-12" | 30-36" | 60-100 | 1-2 ears |
| 🫛 Beans (Bush) | 3-4" | 18-24" | 50-60 | 0.5 lbs |
| 🫑 Zucchini | 24-36" | 36-48" | 45-55 | 6-10 lbs |
| 🥦 Broccoli | 18" | 24-36" | 55-70 | 1-2 lbs |
| 🥬 Spinach | 3-6" | 12-18" | 37-45 | 0.25 lbs |
What Is This Tool?
Whether you’re planning a backyard vegetable patch, designing a raised-bed layout, or maximizing
crop values inside the Roblox game Grow a Garden, our free Grow a Garden
Calculator gives you instant, accurate answers — no spreadsheets, no guesswork.
The tool suite covers five core needs: plant spacing, soil and mulch
volumes, watering requirements, harvest yield estimation,
and fertilizer planning. For Roblox players, dedicated sub-calculators handle
mutation probabilities, item values, and
trade fairness — all cross-referenced against the latest in-game price data.
Every formula in this calculator is grounded in published horticultural guidelines from the
USDA, University Cooperative Extension programs, and the
Grow a Garden community wiki. We update values weekly so you always have current data.
Five Calculators in One
Select any tab in the calculator above to switch tools. Here is what each one
does and why it matters for your garden or game.
Enter your garden dimensions and choose a crop. Instantly see how many plants
fit, row count, planting density per square foot, and a visual grid — for
rectangular, circular, or triangular beds. Supports square and offset
planting patterns.
Stop over-ordering expensive soil. Enter your bed length, width, and depth
to get cubic yards, cubic feet, exact bag counts, and an estimated cost at
your local price per yard. Works for topsoil, compost, and mulch.
Input your garden area, plant type, and climate zone. Get weekly, per-session,
monthly, and annual water needs in gallons plus recommended watering run-time.
Adjusts for humid, average, and hot/dry climates.
Select a crop, enter plant count and growing-season length to get total
harvest weight, per-plant yield, weekly average, estimated market value,
and servings count. Based on Cooperative Extension average yield data.
Enter your garden area, NPK ratio, and application frequency. Get exact
pounds to apply per session and an auto-generated seasonal schedule —
preventing both deficiency and toxic over-application.
Garden Layout Planning
One of the most common beginner mistakes is building a garden that is either too large
to manage or too small to be productive. Our vegetable garden size calculator
removes all the guesswork.
Quick benchmark: A 100 sq ft plot (10 ft × 10 ft) comfortably supplies
salad greens and herbs for 2–3 people. To feed a family of four year-round with varied
vegetables, plan for 600–800 sq ft — or cut that in half using intensive square-foot
gardening techniques.
The vegetable garden size calculator supports three garden shapes:
rectangular, circular, and triangular —
making it perfect for irregular lots and corner beds. Enter your measurements, choose a
crop and planting pattern, and the tool instantly returns:
For raised beds, the 4 ft × 8 ft format (32 sq ft) is the gold standard —
wide enough to reach the centre without stepping on soil, yet compact for beginners.
The tool accepts any custom dimensions you enter.
Roblox Game Tools
Grow a Garden is one of Roblox’s fastest-growing simulation games.
These three dedicated sub-calculators help players maximise earnings and
trade with confidence.
Mutations are rare crop variants — such as
Golden
Rainbow
Shocked
Frozen
Disco
— that can multiply an item’s value many times over. The
Grow a Garden Mutation Calculator computes the probability
of obtaining each mutation type based on your seed rarity, gear level, and
active environmental conditions (night cycle, rain, special events).
💡 How to use it:
Select your seed type and rarity tier, input your current gear level,
and toggle any active conditions. The calculator returns the mutation
probability as a percentage and an expected-value score — so you can
decide whether to wait for a mutation or sell at base value now.
Item prices in Grow a Garden shift constantly with supply, demand, and game
updates. The Grow a Garden Value Calculator provides up-to-date
Sheckle values for every crop, mutation, and item — sourced from the
community wiki and verified against active marketplace listings, updated every week.
💡 How to use it:
Choose your item from the dropdown, select its mutation tier (if any), and enter
the quantity. The tool returns the total current market value and
the average per-unit price — so you always know exactly what your
inventory is worth before entering any trade.
Getting scammed in a trade is frustrating and costly. The
Grow a Garden Trade Calculator calculates the total value of
both sides of a proposed trade and delivers a clear verdict:
✅ Fair
⚠️ Overpaying
🎉 Great Deal
Your Side
Add your items & mutation tiers
Their Side
Add their items & mutation tiers
💡 How to use it:
Add each item and its mutation tier to “Your Side” and
“Their Side.” The calculator totals both sides using live
market values and displays a fairness percentage, a
Sheckle value gap, and a plain-language verdict — giving
you the confidence to negotiate or walk away.
Quick Start
Get accurate results in under 60 seconds — no account, no download, no fee.
Select the tab that matches your goal — Plant Spacing, Soil, Watering,
Harvest, Fertilizer, Mutation, Value, or Trade.
Fill in your garden dimensions, crop type, and conditions. Smart
defaults help you get started in seconds.
Instant calculations appear below your inputs, with primary numbers
and supporting breakdowns so you understand the reasoning.
Change any value and results update instantly. Experiment with
spacing, depths, or trade combinations to find your optimal plan.
Full Sun: 6+ hours (tomatoes, peppers, cucumbers)
Partial Sun: 4-6 hours (lettuce, kale, root vegetables)
Shade: 2-4 hours (herbs, leafy greens)
Never plant the same botanical family in the same spot two seasons in a row. Rotation disrupts pest cycles and reduces soil-borne disease pressure by up to 60%.
Pair compatible crops to boost yield and deter pests naturally. Tomatoes + basil, carrots + onions, and the Three Sisters (corn + beans + squash) are proven combinations.
Succession plant quick crops every 2–3 weeks for continuous harvest. Works best for lettuce, radishes, beans, and cilantro — preventing gluts and harvest gaps.
Look up your USDA Plant Hardiness Zone and local frost dates. Plant cool-season crops in early spring and autumn; warm-season crops only after last frost.
TMost vegetables prefer a soil pH of 6.0–7.0. A basic test kit reveals pH and nutrient levels. Add lime to raise pH or elemental sulfur to lower it.
Select one of the five calculator tabs at the top — Plant Spacing, Soil & Mulch, Watering, Harvest Yield, or Fertilizer. Each tab opens a dedicated tool designed for a specific garden planning task. You can switch between tabs at any time without losing your inputs in the other sections.
In the Plant Spacing and Soil & Mulch calculators, start by entering your garden’s length and width. Choose your preferred unit — feet, meters, inches, or centimetres — from the dropdown next to each field. For circular garden beds, switch to the Circle shape and enter the diameter instead. All unit conversions are handled automatically.
Use the Quick Select dropdown in the Plant Spacing calculator to auto-fill recommended spacing for common vegetables, herbs, and flowers. In the Soil calculator, choose between Topsoil, Compost, or Mulch to get material-specific weight and bag estimates. In the Harvest Yield calculator, pick your crop from the list to load typical yield data automatically.
In the Plant Spacing calculator, select either Square or Offset (staggered) planting pattern. The offset pattern increases planting density by approximately 15% compared to square grid planting — useful when maximising yield in a small raised bed. The visual layout grid updates instantly to show you exactly how your plants will be arranged.
In the Watering calculator, select your climate condition — Humid, Average, or Hot/Dry — to apply an automatic multiplier to your water requirement. Then choose how often you plan to water. The calculator divides your weekly water need by your chosen frequency to give you the exact volume per watering session, so you can calibrate your hose, drip system, or watering can precisely.
Every calculator displays a primary result card at the top of the results panel — plants needed, cubic yards of soil, gallons per week, total harvest weight, or fertilizer quantity — followed by a breakdown of supporting statistics. Use these numbers to create your shopping list, schedule your watering, and plan your planting day with complete confidence in the quantities involved.
The table below summarises the most important planning numbers for common garden types. Use these as starting points when entering values into the calculator above. Actual requirements vary by climate, soil quality, and plant variety — always adjust based on local conditions and your specific soil test results.
| Garden Type | Recommended Soil Depth | Water per Week | Typical Fertilizer Rate | Best For |
|---|---|---|---|---|
| 🌱 Raised Bed | 8 – 12 inches | 1 – 1.5 inches | 1 lb N per 1000 sq ft | Vegetables, herbs |
| 🥗 Vegetable Garden | 6 – 8 inches | 1 inch | 1 – 1.5 lbs N per 1000 sq ft | All food crops |
| 🌸 Flower Bed | 6 inches | 0.5 – 1 inch | 0.5 lb N per 1000 sq ft | Annuals, perennials |
| 🌿 Herb Garden | 6 – 8 inches | 0.5 – 0.75 inch | 0.5 lb N per 1000 sq ft | Culinary herbs |
| 🌳 Tree/Shrub Border | Mulch 2 – 4 inches | 0.5 – 1 inch (established) | Slow-release only | Woody plants |
| 🪴 Container Garden | Full container depth | 2 inches (daily in heat) | Half-strength, weekly | Patios, balconies |
| 🌾 Cover Crop | 4 – 6 inches | 0.5 inch | None (fixes nitrogen) | Soil improvement |
| 🥬 Salad/Cut & Come Again | 6 inches | 1 inch | Light nitrogen top-dress | Lettuce, spinach, kale |
Note: Water requirements increase by 20–30% in hot, dry climates and decrease by 15–20% in humid regions. Use the Watering Calculator above with the appropriate climate multiplier for your location.
Whether you are planting your first raised bed or expanding an established kitchen garden, the plant spacing and soil calculators eliminate guesswork entirely. Know exactly how many tomato plants fit in your 4×8 bed and precisely how many bags of compost to buy before you drive to the garden centre — not after you get there.
The Harvest Yield calculator gives small-scale market gardeners a data-driven forecast of total seasonal production by crop. Enter your plant count and growing season length to estimate total weight, weekly output, and approximate market value. Use this to plan CSA box quantities, farmers market inventory, and crop succession planting schedules weeks in advance.
School garden programmes and community plots need accurate material budgets before applying for grants or purchasing supplies. Use the Soil & Mulch calculator with the cost estimator to generate a precise materials budget — cubic yards, bag counts, weight, and total cost — that can go directly into a grant application or committee proposal without additional calculation.
Professional landscapers can use the Soil & Mulch and Fertilizer calculators to generate accurate material quantities for client quotes in seconds. Enter the bed dimensions and depth, select the material type, and read off cubic yards, bag count, approximate weight, and estimated cost. The entire quoting calculation takes under 60 seconds per garden bed.
The Watering calculator tells you exactly how many gallons per week your garden requires under your specific climate conditions and plant types. Use the gallons-per-session figure to size drip emitters, soaker hose flow rates, or irrigation zone timer settings accurately. Oversized irrigation systems waste water and cause root rot; undersized ones stress plants — this calculator helps you get the specification right from the start.
The Fertilizer calculator works equally well for organic and synthetic fertilizers. Enter the NPK ratio of your chosen organic fertilizer — blood meal (12-0-0), bone meal (3-15-0), or a balanced organic blend — and the calculator tells you exactly how many pounds to apply per session. Avoid the common organic gardening mistake of over-applying nitrogen-rich amendments by calculating the correct rate before you spread.
Sarah wants to build a 4×8 ft raised bed for tomatoes. Plant Spacing: At 18″ spacing (square pattern) she fits 8 plants. Soil: At 10″ depth: 4×8×(10/12) = 26.7 cu ft = 0.99 cubic yards ≈ 14 bags of 2 cu ft topsoil. Water: 32 sq ft × 1.5 in × 0.623 = 29.9 gallons/week. Yield: 8 tomato plants × 12 lbs/plant = approximately 96 lbs over the season. All four of these numbers come from the four calculator tabs above in under two minutes.
James runs a small market stall and wants to know if 50 zucchini plants will meet his weekly demand. Harvest Yield calculator: 50 zucchini plants × estimated 8 lbs/plant over a 10-week season = 400 lbs total, or 40 lbs per week. At a typical market price of $1.50/lb, his estimated revenue is $600 for the season. He can now decide whether to expand his planting or diversify into a second crop to fill the remaining market stall space.
A community garden committee needs to mulch 12 individual plots, each 10×12 ft, to a depth of 3 inches. Total area: 12 × 120 sq ft = 1,440 sq ft. Soil calculator: 1,440 × 0.25 ft (3 inches) = 360 cu ft = 13.3 cubic yards. At $25/yd³ for bulk mulch delivery, total cost = $333. The committee submits this precise figure in their grant application rather than a rough estimate — and gets approved first time.
The offset (staggered) planting pattern fits approximately 15% more plants into the same area compared to a square grid. For a 60 sq ft bed planted with lettuce at 6″ spacing, that is the difference between 120 and 138 plants — nearly an extra 18 heads of lettuce from the same bed, with no additional soil, water, or fertilizer cost. Switch to offset in the Plant Spacing calculator and watch the plant count increase instantly.
The soil calculator gives you the precise mathematical volume your bed requires. In practice, always order 10% more than the calculated figure. Bagged soil compresses during transport and settles after watering — a bed that appears full on planting day will typically settle 1–2 inches over the first month. The extra 10% covers settling, spillage, and the top-dress you will want to add in year two.
The watering calculator gives you the volume your garden needs. When you deliver that water matters almost as much as how much you use. Morning watering reduces surface evaporation losses by up to 30% compared to midday watering, and eliminates the fungal disease risk that comes with evening watering on wet foliage overnight. Apply the calculated volume in one session before 10am for maximum efficiency.
Adding compost to an existing bed fundamentally changes your soil’s water retention and fertilizer needs. A bed amended with 2 inches of compost (calculate the volume in the Soil calculator) retains moisture 20–30% longer, meaning you can reduce your calculated weekly water volume by that proportion. Recalculate your watering schedule in the Watering calculator after any significant soil amendment to avoid overwatering.
The Harvest Yield calculator shows you when your crops will be ready. Use this to plan succession planting — sowing a second batch of fast-maturing crops like lettuce or radish 3–4 weeks after the first, so your second harvest begins just as the first one ends. A continuous harvest from the same bed requires no additional space, just careful timing that the harvest timeline makes visible.
The Fertilizer calculator lets you choose how many applications to split your seasonal total across. Research consistently shows that three smaller applications — at planting, mid-season, and post-first-harvest — produce better plant health outcomes than one large application, even when the total nitrogen delivered is identical. Split feeding reduces leaching losses, prevents nitrogen burn, and delivers nutrients when plants actually need them most.
Every formula in this grow a garden calculator — plant spacing, soil volume, water requirements, harvest yield, and fertilizer rates — is based on published horticultural guidelines from the RHS, University Cooperative Extension programmes, and the American Horticultural Society. Results match the figures produced by professional landscape design software within rounding tolerance.
Every calculation runs locally in your browser. No garden dimensions, plant counts, or yield estimates ever leave your device. There is no account to create, no email address to provide, and no data stored on any server. Your garden planning data is private by default.
This tool is fully responsive and loads in under one second on any device. Use it on your phone while standing in the garden, on a tablet at the potting bench, or on a desktop while planning next season. No app download, no software installation, no account — just open the page and start planning your garden instantly.
Most dedicated garden planning apps charge a subscription for features that are split across these five calculator tabs. This tool gives you plant spacing, soil volume, water requirements, harvest yield forecasting, and fertilizer rate calculation in a single free page with no usage limits, no premium tier, and no advertisements that distort the results. Everything you need to plan a productive garden, at no cost.
Plant spacing depends on the mature size of the plant. Check seed packets or plant tags for specific recommendations. Crowded plants compete for nutrients, water, and sunlight, leading to poor growth and disease. Our calculator uses optimal spacing for maximum yield.
Most vegetable gardens need 1–1.5 inches of water per week. For a 100 sq ft garden at 1 inch per week, that equals roughly 62 gallons. Water deeply 2–3 times per week rather than shallow watering daily — this promotes deeper roots and drought resilience. Our Watering Calculator adjusts automatically for your climate, plant type, and preferred frequency.
NPK represents the percentage of Nitrogen (N), Phosphorus (P), and Potassium (K). For example, 10-10-10 contains 10% of each. Nitrogen promotes leafy growth, phosphorus helps roots and flowers, potassium improves overall plant health. Enter those numbers into our Fertilizer Calculator along with your garden area and desired nitrogen rate. The tool calculates exactly how many pounds to apply per session and generates a full seasonal application schedule to prevent nutrient burn.
Square-foot gardening maximises space efficiency — ideal for small plots, raised beds, and beginners. Traditional row spacing suits large in-ground gardens where you need access for equipment. Both methods work well; choose based on your garden size and how much maintenance effort you prefer. Our Plant Spacing Calculator supports both square and offset patterns.
A 4 ft × 8 ft raised bed that is 12 inches deep requires approximately 1.2 cubic yards (32 cubic feet) — roughly 16 bags of 2 cu ft each. The recommended mix is one-third compost, one-third peat moss or coconut coir, and one-third coarse vermiculite. Our Soil & Mulch Calculator handles any custom dimensions and provides exact bag counts plus a cost estimate.
Fertilize at planting with a balanced fertilizer, then side-dress every 4-6 weeks during the growing season. Heavy feeders (tomatoes, corn, squash) need more frequent feeding. Always water after fertilizing to prevent root burn.
Yields vary based on variety, growing conditions, and care. Our calculator uses average yields per plant. Expect higher yields with optimal conditions (good soil, adequate water, proper spacing) and lower yields with stress or disease.
Apply 2-4 inches of organic mulch around plants. Too thin won’t suppress weeds or retain moisture; too thick can prevent water penetration and harbor pests. Keep mulch 2-3 inches away from plant stems to prevent rot.