Plant Database: Spacing, Depth, Sun & Harvest Data

This plant database gives you the planting numbers that matter for common vegetables, herbs and fruit in a single chart: how far apart to space plants, how far apart to space rows, how many fit in a square foot, how deep to sow, how long until harvest, and whether to start seeds indoors or sow them directly. Search for a plant by name or filter by type and season. The same data powers the spacing, square foot and timing calculators across Garden Voila, so the numbers you see here match the numbers those tools use.

How to read the plant database

Each column answers a specific planting question. Here is what each one means and how to use it.

Type and season

Type groups plants into vegetables, herbs and fruit. Season is more useful for planning. Cool-season crops grow best in spring and fall and tolerate light frost. Warm-season crops need warm soil and air and are damaged by frost. Perennials such as strawberries come back year after year from the same planting.

Sun

“Full sun” means at least six hours of direct sunlight a day, and most fruiting crops do noticeably better with eight. “Full sun to part shade” means the plant still grows well with around four to six hours, which is true of most leafy greens and several herbs. In hot southern summers, lettuce, spinach and cilantro often appreciate afternoon shade because heat pushes them to bolt (flower and turn bitter) sooner.

Spacing and row spacing

Spacing is the distance between plants within a row or bed, measured center to center. Row spacing is the distance between rows in a traditional row garden. Wide row spacing gives room to walk and hoe between rows. In raised beds and intensive plantings, where you never walk on the soil, you can usually ignore row spacing and plant on a grid using the in-row spacing in both directions.

Per square foot

This is the number of plants that fit in one 12-by-12-inch square, as used in square foot gardening. Large sprawling plants such as zucchini and winter squash need more than one square each, so they are shown as “1 per 9 sq ft,” meaning one plant per 3-by-3-foot area.

Sow depth

Sow depth is how deep to plant the seed, in inches. Tiny seeds such as lettuce and carrots go in at about a quarter inch or less. Larger seeds such as beans, peas and squash go in at about an inch. Garlic cloves, potatoes and sweet potato slips go deeper, and strawberry crowns are set level with the soil surface.

Days to maturity

Days to maturity is the typical time until first harvest. Pay attention to the starting point shown in the chart. For crops usually grown from transplants, such as tomatoes, peppers, eggplant and the cabbage family, the count starts on the day you set the transplant in the garden, not the day you sowed the seed. For direct-sown crops, it starts when the seed goes in the ground.

How to start

This column tells you whether to start seeds indoors ahead of time, sow directly in the garden, or plant cloves, tubers, slips or crowns, along with timing relative to your average last spring frost date.

Warm-season and cool-season crops

Sorting crops by season is the single most useful planning step for a vegetable garden, because it tells you when each crop goes in and which crops can share a bed across the year.

Cool-season crops include lettuce, spinach, kale, Swiss chard, broccoli, cabbage, cauliflower, carrots, radishes, beets, onions, garlic, peas, potatoes, parsley and cilantro. They germinate in cool soil, grow well in temperatures roughly between the 40s and 70s °F, and many tolerate light frost. Several, including kale and carrots, taste sweeter after a frost. Most are planted a few weeks before the last spring frost and again in late summer for a fall harvest.

Warm-season crops include tomatoes, peppers, eggplant, cucumbers, zucchini, winter squash, beans, sweet corn, sweet potatoes, okra, basil and dill. They need warm soil to germinate and grow, stall in cool weather, and are damaged or killed by frost. They go in after the last frost date, once nights stay reliably above about 50°F.

Because the two groups occupy the garden at different times, you can often use the same bed twice: spring peas or lettuce, followed by summer beans or squash, followed by fall greens. This is called succession planting, and it is one of the easiest ways to get more food from the same space.

Spacing explained

Spacing numbers can look contradictory between sources, because they are written for different growing methods. Here is how they relate.

In a row garden, plants are set at the in-row spacing within each row, and rows are set at the row spacing. A row of bush beans might have plants 4 inches apart in rows 18 inches apart. The wide gap between rows is mostly path.

In a raised bed or wide bed, there are no paths inside the bed, so plants are set at roughly the in-row spacing in every direction. The same bush beans might be planted 4 to 6 inches apart on a grid, which fits far more plants in the same area.

In square foot gardening, the bed is divided into one-foot squares, and the plant count per square follows a simple rule. Divide 12 by the spacing in inches and square the result. Plants spaced 6 inches apart give (12 ÷ 6)² = 4 per square. Plants spaced 4 inches apart give 9 per square, and plants spaced 3 inches apart give 16. That is why carrots and radishes show 16 per square foot, spinach and beets show 9, and lettuce shows 4.

Some crops break the rule because they are trained upward. A tomato needs about 2 feet of space when sprawling, but a single staked or caged indeterminate tomato can be grown in one square foot, because it grows up rather than out. Vining cucumbers and pole beans are similar when grown on a trellis.

To turn spacing into plant counts for a whole bed, use the plant spacing calculator or the square foot gardening calculator.

Planting depth rule of thumb

When you have a seed that is not in the database and the packet is lost, a reliable rule is to plant seeds at a depth of two to three times their diameter. A bean seed about a third of an inch across goes in about an inch deep. A lettuce seed barely a sixteenth of an inch wide is pressed onto the surface and covered with a dusting of soil.

Planting too deep is a more common mistake than planting too shallow. Small seeds hold little stored energy, and if they are buried too deeply the seedling can run out before it reaches light. Some seeds, including many lettuces, need light to germinate and should barely be covered.

Soil type shifts the right depth a little. In light, sandy soil that dries quickly, plant slightly deeper so the seed stays moist. In heavy clay that crusts, plant slightly shallower and cover with fine compost rather than clay. The planting depth calculator gives crop-specific depths.

Days to maturity: what the number really means

Days to maturity is an average from good growing conditions, not a promise. It is best used to compare varieties and to judge whether a crop has time to finish before your first fall frost.

• Check where the count starts. For transplanted crops, add the six to ten weeks of indoor growing to get the full time from seed. A tomato listed at 70 days takes closer to four months from sowing.
• Weather changes the count. Cool springs slow warm-season crops, and heat waves push cool-season crops to bolt early. Expect real dates to vary by a week or two in either direction.
• Fall plantings take longer. As days shorten and temperatures fall, growth slows. Many gardeners add about two weeks to days to maturity for crops planted in late summer for fall harvest.
• Harvest windows vary. Some crops, such as radishes and sweet corn, have a short peak and should be picked promptly. Others, such as kale, chard and herbs, can be harvested over many weeks.

To turn a planting date into a harvest date, use the harvest date calculator.

Starting indoors or sowing directly

Some crops are best started indoors and transplanted, and others are best sown where they will grow. The difference comes down to season length and how well the roots tolerate disturbance.

Start indoors for crops that need a long warm season to produce, especially in northern states where the frost-free season is short. Tomatoes, peppers and eggplant are the classic examples, typically started six to ten weeks before the last frost. Broccoli, cabbage and cauliflower are often started indoors too, so they can mature before summer heat. Onions are frequently started indoors in late winter or planted as sets.

Sow directly for crops with taproots or sensitive roots that do not transplant well. Carrots, radishes, beets and other root crops should always be direct sown, because transplanting can fork or stunt the root. Beans, peas and corn germinate quickly in the right soil and gain little from an indoor start. Cucumbers and squash can be started indoors, but only a few weeks ahead, in individual pots, and planted out gently.

Your seed-starting dates count backward from your average last spring frost date. The seed starting calculator does the date math once you know your frost date.

Succession planting with the database

The season and days-to-maturity columns together make it easy to plan two or even three crops in the same space in one year. Start with a quick cool-season crop in spring, follow it with a warm-season crop once frost danger has passed, and finish with another cool-season crop for fall. Radishes, at around a month to harvest, can fit almost anywhere. Spring lettuce can be followed by bush beans, which in turn can be followed by fall spinach or kale. To check that a fall crop has time to finish, count back from your average first fall frost date by the crop’s days to maturity, plus about two weeks for slower growth in shortening days.

Fast crops are also ideal for staggered sowing. Instead of planting all your lettuce or beans at once and getting a glut, sow a smaller amount every two to three weeks for a steady harvest.

Using this data with the calculators

The plant database is the foundation for several other tools. The plant spacing calculator and square foot gardening calculator use its spacing figures. The seed quantity calculator uses spacing to estimate seed counts, and the garden watering calculator uses weekly water needs. As the database grows, the plant finder and garden planner will draw on it to suggest crops and layouts for your conditions.

Where the numbers come from

The values in this database are typical ranges for home gardens, consistent with common seed catalog listings and US university extension planting guides. They are a reliable starting point, but varieties within a crop can differ a lot. A compact patio tomato and a vigorous heirloom need very different space, and an early cabbage can mature a month or more before a storage variety. When your seed packet or plant tag gives a figure for the exact variety you are growing, use it. For crop choices suited to your region, your state’s Cooperative Extension service publishes recommended variety lists and planting calendars.

Frequently asked questions