Full Sun vs Partial Sun vs Partial Shade: Hours That Count

Updated September 2026 · Garden Advice Guide

The difference in full sun vs partial sun vs partial shade is a count of direct sun hours, plus when those hours arrive. Full sun means 6 or more hours of direct sun a day during the growing season. Partial sun means 4 to 6 hours, and the plant can take some of that in the heat of the afternoon. Partial shade means roughly 3 to 6 hours, with the sunny end of that overlapping partial sun, but the plant wants those hours in the morning and needs protection after about 1 p.m. Full shade means under 3 hours of direct sun, or bright dappled light all day under a high canopy. The labels sound vague because the tags never tell you the part that matters most: a morning hour and a 3 p.m. hour are not the same hour.

Your zone changes how hard afternoon sun hits. Look up your USDA hardiness zone before you read the rules below, because "full sun" in zone 4 and "full sun" in zone 9 are different experiences for the same plant.

Updated September 2026

Full sun vs partial sun vs partial shade, defined

Most plant references use the same four bands. The trouble is that partial sun and partial shade overlap on the clock, so the time of day and the plant's tolerance are what separate them.

"Part sun" and "part shade" are used interchangeably on a lot of nursery tags, so treat them as one band of 3 to 6 hours and let the rest of the tag tell you which end of it the plant likes. Our shrubs by zone and perennials by zone tables use exactly these bands in their light columns, so once you have hours for a spot, those lists become a filter you can actually apply.

What counts as a sun hour

A sun hour is an hour when direct sunlight lands on the spot, meaning the sun itself is visible from where the plant sits and it casts a crisp shadow. Bright sky is not sun. The north side of a white house can be glowing with light all afternoon and still count as zero sun hours.

Three rules make the count honest.

Count only the strong hours. In midsummer, the sun at 6:30 a.m. or 7:45 p.m. is so low that it delivers a small fraction of the energy of the noon sun. A practical cutoff is to count direct sun between about 8 a.m. and 6 p.m. daylight saving time and ignore what falls outside that window. A spot that catches sun only from 6 to 8 a.m. is a shade spot, whatever the hour count says.

Know where solar noon actually is. Because of daylight saving time, the sun is highest around 1 p.m. on the clock across most of the country, and later still on the western edge of a time zone. That shifts "afternoon sun" later than people expect. The hottest, harshest sun on a plant runs from about 1 p.m. to 5 p.m. daylight time, because the air temperature keeps climbing for hours after the sun peaks.

Count in the season the plant grows. Mapping sun in March tells you almost nothing about July. The sun is far higher in summer, so shadows are shorter, and deciduous trees have not leafed out yet in early spring. A bed that gets 7 hours of sun on April 1 can drop to 3 hours once the neighbor's maple fills in.

Shadow length through the year

The sun's height at noon changes a lot between seasons, and that decides how far a fence, a house or a tree throws shade. This table gives the length of a noon shadow as a multiple of the object's height.

Read it this way: at 40°N, a 6 foot privacy fence throws a noon shadow of about 2 feet in late June, 5 feet at the equinoxes and 12 feet in late December. That is why a bed along the north side of a fence can be a full sun bed in summer and a shade bed from October to March. For summer flowers and vegetables, the June column is the one that matters. For anything that grows in fall, winter or early spring, such as garlic, overwintered greens or a cold frame, the December column decides.

One more summer detail catches people out. Between the spring and fall equinoxes, the sun rises north of due east and sets north of due west. So a bed on the north side of a house picks up a little direct sun early in the morning and again in the evening in June and July. Those hours are low and weak, and they vanish entirely by fall.

How to map sun hours across your yard

Guessing sun hours is the most common reason a plant sulks for three years and never settles. Mapping takes one clear day and a pencil.

1. Pick a clear day between late May and early August. Near the summer solstice gives you the maximum, which is the number plant tags assume. If you can repeat the map once in September, even better, since that shows how quickly shade creeps in.
2. Sketch the yard to rough scale. House, fences, trees, beds and paths. Grid paper makes it faster, with each square worth 2 or 5 feet.
3. Pick the spots you care about and number them. Every existing bed, every place you want to plant, and the corners of the lawn.
4. Walk the yard every hour from 8 a.m. to 6 p.m. At each spot, write S for direct sun, D for dappled light or P for full shade.
5. Total each spot. Count S as a full hour, count D as half an hour, and note whether most of the S hours fell before or after 1 p.m.
6. Label each spot with the band from the definitions table, plus "AM" or "PM" for when the sun arrives.

If you cannot be home all day, set a phone on a windowsill or a fence post pointed at the yard and use a time lapse, or take a photo from the same upstairs window every hour. Sun path apps that overlay the sun's track on a camera view are a good shortcut for planning, but they do not know about your neighbor's tree, so confirm with a real walk before you plant anything woody.

Worked example: four spots in one back yard

Here is a map from a zone 6 yard at about 40°N, mapped on a clear day in late June. The back of the house faces south, a 6 foot fence runs along the west side with a mature maple just past it, and a neighbor's honey locust overhangs the east side of the yard.

Spots A and C have the same 5 hours on paper, and they are opposite sites. Spot A gets its sun during the cool part of the day and goes into shade before the heat peaks, which is exactly what a partial shade plant wants. Spot C sits in dappled light all morning and then takes the full force of the afternoon. A bigleaf hydrangea in spot A thrives. The same hydrangea in spot C wilts every afternoon in July. That single difference is why the hour count alone is not enough.

Morning sun vs afternoon sun

Morning sun and afternoon sun deliver similar light, but they arrive in very different conditions.

• Air temperature. At 10 a.m. the air is still cool from the night. By 3 or 4 p.m. it is near the high for the day. A leaf in afternoon sun is taking in light and heat at the same time.
• Leaf temperature. A sunlit leaf in still afternoon air can run well above air temperature. Plants cool themselves by moving water out through the leaves, and when roots cannot keep up, the leaf edges scorch.
• Soil moisture. Morning sun lands on soil that is still damp from the night. Afternoon sun lands on soil the morning already dried out.
• Dew. Morning sun burns off dew quickly, which cuts leaf disease. A shade spot that only gets late sun stays wet for hours longer, which is why powdery mildew and black spot favor beds with no morning light.

That gives two practical rules. First, a partial shade plant should get its hours in the morning, full stop. Second, a full sun plant is happiest with its hours centered on midday, and the farther south you garden, the more it benefits from a little relief in late afternoon.

How your zone shifts the rules

The same label behaves differently across the country, and plant tags are written for the middle of it.

This is also why the same shrub carries different sun advice in different catalogs. A catalog printed in Oregon and one printed in Georgia are both telling the truth for their own summers.

Dappled light, filtered light and bright shade

Dappled light is sun broken into moving spots by a tree canopy. It is the best light many shade plants ever get, and it is the hardest to count.

Count dappled hours at about half value. Four hours of dappled light under a thin canopy delivers roughly what two hours of direct sun would. That is a planning estimate, not a measurement, but it keeps you from calling a woodland edge "partial sun."

The tree decides how dappled. Honey locust, birch, serviceberry and most oaks cast light, open shade, and lawn grass will grow beneath them, though even there a lawn needs the right seed, which our guide on why grass seed is not growing sorts out by sun hours. Norway maple, sugar maple, beech, southern magnolia and any spruce or hemlock cast dense shade where little grows. Our evergreen trees by zone guide flags hemlock as the conifer that grows in that kind of shade, and our fast growing shade trees guide notes which canopy trees let light through, which is worth checking before you plant a tree that will reshape the light for the next forty years.

High shade is brighter than low shade. A canopy that starts 30 feet up lets in sky light from the sides all day. The same leaf cover at 8 feet blocks it. Removing the lowest limbs of a mature deciduous tree, a job called limbing up, can turn full shade into good partial shade without taking the tree down.

Bright shade is real. A spot with no direct sun but open sky overhead, such as the north side of a house with nothing across the lawn, grows a much wider range of plants than the same spot under a deck. If you can read a newspaper there comfortably at noon, it counts as bright shade.

If you like numbers, a basic light meter or a free phone light meter app gives a rough check. Direct summer sun reads somewhere around 80,000 to 100,000 lux. Open bright shade tends to fall in the 10,000 to 25,000 range, and deep shade under dense trees can drop to a few thousand. Phone sensors are not precise, so use the readings to compare spots in your own yard rather than to classify a single spot.

How to read the sun symbols and wording on plant tags

Tags compress all of this into a symbol and three words, and both follow a pattern.

The first word is the preference. "Sun to part shade" and "part shade to sun" describe different plants. The first word is where the plant performs best, and the second is how far it will stretch.

Two icons means a range. A sun icon next to a half filled circle means the plant grows across both bands, and the first icon is still the one it prefers.

Foliage color is a clue the tag skips. Gold and chartreuse leaves usually need some sun to keep their color and burn in hot afternoon sun. Blue leaves, such as blue hosta, need shade to hold their waxy coating. Purple and burgundy leaves fade to muddy green in too much shade. Variegated leaves have less green tissue and usually want less sun than the plain green form of the same plant.

Flowering and fruiting need more sun than foliage. A plant grown for its leaves tolerates the low end of its range. A plant grown for its flowers or its crop needs the high end. Once you have hours for a wall or fence, our flowering vines by zone guide shows which climbers bloom on a shady north wall and which need a sunny arbor.

Sun hours for vegetables and herbs

Vegetables follow a simple rule: the more of the plant you eat that is a fruit, the more sun it needs.

A tomato with 5 hours of sun will grow, but it sets far fewer fruit and the fruit tastes flat. Lettuce with 4 hours of morning sun is often better than lettuce in full sun, because afternoon heat is what pushes it to bolt, which our guide on how to grow lettuce covers in detail. In a yard with limited sun, give the sunniest patch to fruiting crops, put greens in the partial shade spots, and skip corn and melons entirely. Our raised bed garden layout ideas page shows how to orient beds north to south and put tall crops on the north end so they do not shade the rest.

Signs a plant has the wrong light

Plants tell you within a season when the light is wrong, and the symptoms are different in each direction.

Some afternoon wilting on a hot day is normal for big leaved plants such as hydrangea, squash and ligularia. The test is the evening. If the plant perks back up by 8 p.m. with no scorch, it is managing. If it is still limp, or the leaf edges are browning, it has too much sun for the moisture it has. More water can buy some tolerance in partial sun, but it does not turn a shade plant into a sun plant.

Changing the light you have

You cannot move the sun, but you can adjust how much of it reaches a bed.

• Limb up or thin a deciduous tree. Removing the lowest branches and thinning the crown lets in side light and turns dense shade into dappled light. Hire a certified arborist for anything big, and do not do this to spruce, fir or other conifers, which do not regrow from bare wood.
• Add afternoon shade in hot zones. A 30 to 40 percent shade cloth on a simple frame over the west side of a vegetable bed makes a real difference to lettuce, peppers and tomatoes in zones 8 and up during the hottest weeks.
• Use reflected light. A white or light painted wall or fence bounces a surprising amount of light into a shady bed. It does not add sun hours, but it brightens the shade.
• Grow in containers. Pots can follow the sun. That is the simplest way to grow tomatoes or herbs in a yard with no 6 hour spot, and our container gardening guide covers the pot sizes that keep them watered.
• Choose for the site instead of fighting it. A shade bed full of plants that want shade looks better than a shade bed full of struggling sun plants. For shade gardens where browsing animals are also a problem, our deer resistant shade plants list sorts the options by light level and dry or moist soil.

One caution when you do plant in full sun: seedlings and nursery plants grown under cover need a week or two of gradual exposure before they can take it. A plant that came straight from a greenhouse will scorch in its first full day outdoors, which is what hardening off seedlings is designed to prevent.

Frequently asked questions

How many hours of sun is full sun?

Six hours or more of direct sun per day during the growing season. The hours between about 8 a.m. and 6 p.m. daylight time are the ones that count, because very early and very late sun is too low to deliver much energy. Fruiting vegetables and most flowering perennials do best with 8 hours or more.

What is the difference between partial sun and partial shade?

Both sit in the same 3 to 6 hour band, with partial sun at the sunny end of it, about 4 to 6 hours, and many tags use the terms interchangeably. The practical difference is tolerance and timing. A partial sun plant prefers the sunny end of that range and can take afternoon sun. A partial shade plant prefers the shady end and wants its sun in the morning, with shade from early afternoon onward.

Is morning sun better than afternoon sun?

For shade loving and partial shade plants, yes. Morning sun arrives when the air is cool and the soil is moist, so the plant gets the light without heat stress. Afternoon sun comes with the day's highest temperatures. Four hours of afternoon sun stresses a plant far more than four hours of morning sun, especially in zones 7 and warmer.

Does dappled shade count as partial shade?

Roughly. Count dappled light at about half value, so four hours of dappled light works out to around two hours of direct sun. Light dappled shade under a high, open canopy suits most partial shade plants. Dense dappled shade under a low maple or beech behaves more like full shade.

How do I measure how much sun my garden gets?

Choose a clear day between late May and early August and check each spot once an hour from 8 a.m. to 6 p.m., marking direct sun, dappled light or shade. Total the direct hours, count dappled hours at half, and note whether the sun came in the morning or afternoon. A time lapse from a window works if you cannot be home all day.

Can a full sun plant grow in partial shade?

It will usually survive, but it will not perform. Expect fewer flowers or fruit, weaker and leaning stems, and more leaf disease. Flowering and fruiting plants suffer most. Plants grown for foliage handle the move better. Some full sun plants do benefit from a little afternoon shade in the hottest parts of the South and West.

What does a half filled circle mean on a plant tag?

It means partial sun or partial shade, about 3 to 6 hours of direct sun. Read the wording next to it to decide where the plant goes. "Part shade to sun" prefers some shade but can stretch into more sun, while "part shade to shade" leans shady and should get only morning sun.

Does the amount of sun change during the year?

Yes, a lot. The sun is much higher in summer, so shadows are short, and much lower in winter, when a fence or house can throw a shadow two or three times its own height at noon. Deciduous trees also change the picture when they leaf out in spring and drop leaves in fall. Map summer beds in June or July and winter growing spots in late fall.