What to Plant in April in Pennsylvania

April is the biggest planting month in Pennsylvania for most gardeners. The soil is finally warming up, daylight is stretching past 13 hours, and — depending on where you are — the frost risk is dropping fast. If you’ve been starting seeds under grow lights since February, this is the month your patience starts paying off.

That said, April in PA is a tale of two states. Gardeners in the Philadelphia suburbs can transplant cool-season crops by early April, while folks in Pittsburgh, the mountains, and the northern tier are still watching frost advisories. Knowing your zone and frost date makes the difference between a great April and a frustrating one.

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What to Direct Sow Outdoors in April

April opens the door for direct sowing across most of PA — but stick to crops that can handle cool soil and the occasional frost. These are the cold-tolerant workhorses of spring gardening.

Peas

If you didn’t get peas in the ground in March, early April is your window. Peas actually prefer cool weather — once summer heat hits, they’re done. Sow them 1 inch deep, 2 inches apart, and give climbing varieties a trellis or some twine to grab onto. I put mine along a section of chicken wire and they climb it beautifully.

Peas germinate in soil as cool as 40°F, so even zone 5b gardeners can get them in by mid-April.

Carrots

Carrots are an April staple across all PA zones. They’re slow to germinate (10–21 days is normal, so don’t panic) and need loose, rock-free soil to grow straight. If you’re dealing with PA’s typical heavy clay, consider a raised bed or at least work in plenty of compost to loosen the top 8–10 inches.

Sow carrot seeds ¼ inch deep in rows 12 inches apart. Thin to 2 inches apart once seedlings are a couple inches tall. The thinning step matters — crowded carrots end up stunted and forked.

Beets

Beets handle cool soil well and can go in the ground as soon as soil temps hit 40°F. That means early-to-mid April for zones 6a–7a, and late April for zones 5a–5b. Plant seeds 1 inch apart, ½ inch deep. Each beet “seed” is actually a cluster of seeds, so you’ll need to thin to 3 inches apart once they sprout.

Beet greens are edible and delicious — don’t throw away your thinnings.

Potatoes

The old folk wisdom says plant potatoes on St. Patrick’s Day, but that’s too early for most of PA. A better rule: plant when soil temperature hits 45°F consistently. For zones 6a–6b, that’s usually mid-to-late April. For zone 7a, early April works. Zone 5b gardeners should wait until the last week of April or even early May.

Cut seed potatoes into pieces with at least two eyes each, let the cut sides dry for a day or two, and plant 4 inches deep, 12 inches apart, in trenches. You’ll hill soil around the stems as they grow — this is what gives you more potatoes per plant.

Spinach, Lettuce, and Other Greens

If you started these in March, keep succession planting through April for a longer harvest window. If you haven’t planted any yet, you’re not late — April is prime time for greens across all PA zones.

Direct sow spinach ½ inch deep. Scatter lettuce seed on the surface and press it lightly into the soil — lettuce needs light to germinate, so don’t bury it. Arugula and kale can also go in now. All of these handle frost with no issues.

Radishes

Radishes are the fastest reward in the garden — 25–30 days from seed to plate. Sow ½ inch deep, thin to 1 inch apart, and succession plant every 10 days through April for a steady supply. They’re a perfect “morale booster” crop when you’re waiting for everything else to grow.

Swiss Chard>

Chard is one of the most underrated spring crops. It handles frost, grows in partial shade, and produces all season long — from April through first hard frost in fall. Sow seeds 1 inch apart, ½ inch deep, and thin to 6 inches. The colorful stems (Rainbow chard especially) look good enough to plant in a flower bed.

Onion Sets

If you started onion seeds indoors back in January, April is when those transplants go outside. If you didn’t start from seed, onion sets are the shortcut — small bulbs you plant directly in the ground in April. Push them in 1 inch deep, 4 inches apart, with the pointy end up.

Penn State Extension’s onion guide recommends long-day onion varieties for PA — they need the 14–16 hours of daylight we get in summer to form full bulbs. Short-day varieties (common in the South) won’t size up properly here.

What to Transplant Outdoors in April

If you’ve been growing seedlings indoors since February or March, April is when several of them are ready to move outside — but only the cold-tolerant ones. Tomatoes and peppers stay inside for now.

Broccoli, Cabbage, and Cauliflower

These brassicas are tough. They handle light frost and actually prefer cool weather for heading. Transplant them outdoors 4–6 weeks before your last frost date — that means early-to-mid April for zones 6b–7a, and late April for zone 6a.

Harden off your seedlings first — set them outside for a few hours each day for a week before transplanting. Going straight from grow lights to full sun shocks them, and shocked brassicas bolt instead of forming heads.

Lettuce and Kale Transplants

Lettuce and kale seedlings started indoors can go outside by early-to-mid April in zones 6a–7a. They’re frost-hardy and will establish faster than direct-sown seed, giving you an earlier harvest. Space lettuce transplants 8 inches apart, kale 12–18 inches.

What to Keep Indoors in April (Not Ready Yet)

I know it’s tempting — those first few 70°F days in April feel like summer. But the soil is still in the 50s in most of PA, and a hard frost can show up through mid-April in zones 6a–6b and through late April or early May in zones 5a–5b.

Keep these indoors until May:

• Tomatoes — need soil temps above 60°F and zero frost risk. Even zone 7a gardeners should wait until late April at the earliest, and a May transplant is safer.
• Peppers and eggplant — even less cold-tolerant than tomatoes. These want nighttime temps consistently above 50°F before they go outside.
• Cucumbers, squash, and melons — warm-season crops that rot in cold, wet soil. Wait for May or even June.
• Basil — dies at the first hint of frost. Keep it under lights until all frost risk has passed.
• Beans and corn — need warm soil (60°F+). Planting in cold soil means slow germination and higher risk of seed rot.

April Trees and Shrubs

April is the ideal month to plant trees and shrubs across all PA zones. The soil is thawed, consistently moist from spring rain, and warming up — perfect conditions for root establishment.

Fruit Trees

If you missed the bare-root window in March, you can still plant container fruit trees throughout April. Apples, pears, cherries, and plums all do well planted in April. Peaches are great in zones 6a–7a — they need that moderate winter cold for proper dormancy but can struggle in zone 5a’s extreme lows.

Dig the hole twice as wide as the root ball but no deeper — planting too deep is one of the most common mistakes with trees. The root flare (where the trunk meets the roots) should be visible at or just above soil level.

Berry Bushes

April is prime time for planting blueberries, raspberries, and blackberries. Blueberries need acidic soil (pH 4.5–5.5), which is a challenge in parts of PA where the clay runs more neutral. A soil test tells you exactly where you stand — and the Arbor Day Foundation’s planting guide has solid general advice for getting trees and shrubs established.

Raspberries and blackberries are less fussy about soil pH and spread aggressively. Plant them where you want a permanent patch — they’re hard to remove once established.

April Lawn Care

April is a critical month for cool-season lawns in PA (tall fescue, Kentucky bluegrass, perennial ryegrass — the grasses that actually grow well here).

Pre-Emergent Crabgrass Control

This is the single most time-sensitive lawn task of the year. Apply pre-emergent herbicide before soil temps hit 55°F consistently, which is when crabgrass seeds germinate. In most of PA, that window is early-to-mid April. Zone 7a gardeners should apply in late March or the first week of April.

The trick: if you see forsythia blooming in your neighborhood, you’re in the right window. Forsythia bloom timing roughly tracks crabgrass germination timing — it’s an old landscaper’s rule of thumb that actually works.

Don’t Overseed in April

If your lawn needs overseeding, wait until late August or early September. Spring-seeded grass faces too much competition from weeds and summer heat stress. April is for feeding established grass and stopping weeds, not starting new seed.

First Mowing

Start mowing once grass hits 3.5–4 inches and cut it to about 3 inches. Never remove more than one-third of the blade height in a single mow. PA cool-season grasses do best mowed high — shorter cuts stress the grass and let weeds take over.

April Prep Tasks (All Zones)

Soil Prep

• Don’t work wet soil. This bears repeating because it’s the #1 April mistake in PA. Grab a handful of soil and squeeze — if it forms a sticky ball, wait a few more days. Working wet clay destroys the soil structure and creates concrete-like clumps that last all season.
• Add compost to any beds you’re planting this month. Work it into the top 6–8 inches.
• If you haven’t tested your soil in the last 2–3 years, send a sample to Penn State Extension — it’s about $10 and tells you your pH, nutrient levels, and exactly what amendments you need.

Hardening Off Seedlings

Any seedlings heading outside this month need to be hardened off first. Start by setting them outside in a sheltered, shady spot for 2–3 hours. Each day, increase the time and sun exposure over 7–10 days. This transition prevents transplant shock and sunburn on leaves that have never seen real sunlight.

Pest Watch

• Cabbage worms appear as soon as you transplant brassicas. Watch for small white butterflies hovering around your plants — they’re laying eggs. Floating row covers keep them off without pesticides.
• Slugs love the cool, wet conditions of PA’s April. If you’re finding holes in lettuce and greens, check under boards or mulch in the morning — that’s where they hide during the day.

April Planting Calendar at a Glance

FAQ