Early Spring Sun Exposure: How It Really Works (And Why Your PNW Garden Timing Depends on It)

It looks like spring is here. The daffodils are blooming, the cherries are putting on a show, and that first warm afternoon has you standing in the yard thinking it's time to plant. But that warmth is deceiving you. The air might feel like 60 degrees, but your garden is telling a completely different story.

Early Spring Sun Exposure Isn't What You Think

At our latitude in the Pacific Northwest (around 47°N for Seattle, 45°N for Portland), the sun's position changes dramatically between March and June. In mid-March, the sun peaks at roughly 38 degrees above the horizon at solar noon. By late June, it climbs to about 65 degrees. That 27-degree difference changes everything about what your garden beds actually receive.

A lower sun means longer shadows. Your house, your fence, your neighbor's trees, all of those cast shadows that stretch two to three times further in March than they will in summer. A bed that gets eight hours of direct sun in July might only see three or four hours right now, and the light hitting it is less intense because it's arriving at a steeper angle through more atmosphere.

Sun height in the Pacific Northwest at 47.6°N latitude. In summer, the sun arcs high overhead at about 66 degrees, rising in the northeast and setting in the northwest. In spring and fall, it drops to around 42 degrees on a moderate path from east to west. In winter, it barely climbs to 19 degrees, hugging the horizon from southeast to southwest. The lower the path, the longer the shadows across your garden beds.

We're also working with less daylight. March gives us roughly 12 hours from sunrise to sunset. By the summer solstice, we're up near 16 hours. That's four extra hours of photosynthesis your plants aren't getting yet. And then there's the PNW wildcard: cloud cover. Even on what feels like a bright March day, a lot of that light is diffused through clouds, scattered and weaker than the direct sun your warm-season crops need.

PNW spring vs. summer light, side by side. In March, the sun sits at about 42 degrees with 12 hours of weak, diffused light. By June, it climbs to 66 degrees with 16 hours of strong, direct sun. Same garden, very different growing conditions.

Soil Temperature Is the Number That Matters

Here's what most people get wrong. They check the weather forecast, see 58°F, and think that's what their garden is working with. It's not. Your soil is running 10 to 15 degrees cooler than the air temperature in early spring, and soil temperature is what controls germination and root growth. A $5 soil thermometer pushed four inches into the bed at 8 a.m. (before the sun warms things up) gives you the real number. In March, most PNW beds sit between 42 and 50 degrees at root depth.

What to Plant Now vs. What to Wait On

Cool-season crops are built for this. Lettuce, spinach, kale, peas, radishes, and arugula all germinate in soil as cool as 40°F and grow well with just three to five hours of direct light. They actually prefer the cooler temperatures and bolt (go to seed) when it gets too hot. Early spring in the PNW is exactly what these plants want.

Cool-season crops that thrive in early spring PNW light. Three to five hours of sun and soil temps as low as 35°F is all they need.

Tomatoes, peppers, squash, cucumbers, beans, and corn are a different story. These need soil temperatures consistently above 60°F, eight or more hours of strong direct sun, and warm nights. Putting them out in March is basically setting money on fire. They'll sit there, stressed and stunted, until conditions catch up in late May or June.

Full sun crops need six to eight-plus hours of direct light. Hold off on these until late May or June.

Use Your Microclimates

Every yard has warm spots and cool spots, and knowing which is which is how you get ahead. Your south-facing bed against the house wall absorbs and reflects heat, making it your warmest, earliest-to-plant zone. An east-facing bed gets gentle morning light, perfect for leafy greens that scorch in hot afternoon sun. The north side of your house? That's your shade garden. Ideal for spinach and kale, even into summer when other spots get too hot.

Pay attention to fences, tree canopy (especially deciduous trees that haven't leafed out yet but will shade everything by May), and hard surfaces like concrete or stone that hold and radiate heat.

Match your crops to your yard's microclimates. South-facing beds get the most sun and warmth; north side stays shady and cool.

Map It Once, Use It All Season

Here's the single most useful thing you can do to understand your early spring sun exposure: pick a clear day and check your beds every two hours from 8 a.m. to 6 p.m. Write down which spots get direct light and which sit in shadow. Do it once in March and once in June. You'll have a sun map that takes the guesswork out of every planting decision.

This is exactly what I help my Executive Kitchen Garden clients figure out. Designing a garden that works with your actual light patterns, your actual soil conditions, your actual space, not some generic planting calendar that doesn't know your yard.

Not sure how this applies to your garden? Let's talk about it. Book a Kitchen Garden Consultation Session and we'll look at your space together.

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March bookings are open for both the Executive Blueprint and one-on-one consultation sessions.

→ The Blueprint is the full design phase - soil assessment, crop selection, succession plan, and layout - everything covered in this post, done for your specific space. Book here.

→ Consultation sessions are a good fit if you want to work through one piece of it yourself with guidance. Either way, the spring planting window sets the deadline, and spots fill before it arrives. Book here.