How to Grow Kale in Pennsylvania: Step-by-Step for PA Zones 5a-7a

You have a flat of kale seedlings on the kitchen counter, the last frost date is creeping closer, and you are wondering whether to set them out this weekend or wait another week. Maybe you have never grown kale before and the seed packet instructions feel generic — they say nothing about Pennsylvania’s clay soil, our humid summers, or the fact that fall kale tastes completely different from spring kale. The gap between seed packet advice and what actually works in a PA garden is exactly what trips up first-time growers.

This guide walks you through every step of growing kale in Pennsylvania, from preparing your soil to pulling your last frost-sweetened harvest in December. Every recommendation is tuned to PA zones 5a through 7a, with specific dates, soil temperatures, and techniques that account for our clay soils, wet springs, and long fall growing window. If you can follow a recipe, you can grow kale here.

Below you will find site selection, soil prep, indoor seed starting, direct sowing, transplanting, watering and feeding schedules, mulching, pest prevention, succession planting, season extension, and harvesting techniques. Each section builds on the one before it, so reading straight through gives you the full picture — or jump to any section using the guide below.

Choosing the Right Spot for Kale in Pennsylvania

Kale needs at least 6 hours of direct sunlight per day for strong, compact growth. In spring and fall — the two main growing seasons in PA — sun angle is lower than summer, so a spot that gets full sun from April through November is ideal. South-facing garden beds, open lawn edges, and any area without tree shade during the morning hours will work well.

That said, kale is more shade-tolerant than most vegetables. If your only option gets 4 to 5 hours of direct sun, kale will still grow. The leaves will be slightly thinner and the plants will spread more laterally, but you will still get a usable harvest. This makes kale a good candidate for partially shaded yards, north-facing properties, and the edges of tree lines that get dappled afternoon light.

Drainage Matters More Than You Think

Pennsylvania’s clay-heavy soils hold water after rain, and kale roots sitting in saturated ground for more than 24 hours start to suffer. Root rot and stunted growth are the most common problems in poorly drained beds. Before planting, check drainage by digging a hole 8 inches deep, filling it with water, and timing how long it takes to drain. If the water is gone within 1 to 2 hours, drainage is fine. If it takes 4 or more hours, you need to amend the soil or switch to a raised bed.

If your site drains slowly, consider growing kale in raised beds, which solves the drainage problem entirely by elevating the root zone above the native clay. Even a bed just 8 to 10 inches tall makes a significant difference in how fast excess water moves away from kale roots after a spring downpour.

Soil Preparation for PA Clay

Getting the soil right before planting saves you months of problems later. Kale is a heavy feeder that grows best in loose, fertile soil with a pH between 6.0 and 7.0. Most Pennsylvania soils test slightly acidic (5.5 to 6.5) and tend toward heavy clay, which means you will likely need both organic matter for structure and lime for pH adjustment.

Step-by-Step Soil Prep

1. Test your soil. Send a sample to your county extension office or use a home kit. You need to know your pH, nitrogen, phosphorus, and potassium levels before adding anything. Guessing leads to over-liming or under-fertilizing, both of which hurt kale production.

2. Add compost. Spread 3 to 4 inches of aged compost over the planting area. This is the single most important amendment for PA clay. Compost breaks up compaction, improves drainage, feeds soil biology, and adds slow-release nutrients. Work it into the top 8 to 10 inches with a garden fork or broadfork. Do this in fall if possible — freeze-thaw cycles over winter will further loosen the soil.

3. Adjust pH if needed. If your test shows pH below 6.0, apply dolomitic garden lime at the rate recommended by your soil test. Dolomitic lime also supplies calcium and magnesium, both of which kale needs for healthy leaf development. Apply lime in fall — it takes 2 to 3 months to adjust pH. Spring applications work but take longer to take effect.

4. Add a balanced fertilizer. At planting time, work in 2 to 3 pounds of 10-10-10 granular fertilizer per 100 square feet. This gives kale a baseline of nitrogen, phosphorus, and potassium to get started. Organic growers can substitute an equal volume of composted manure plus a cup of bone meal per 50 square feet.

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Starting Kale Seeds Indoors

Indoor seed starting gives you a 4 to 6 week head start on the growing season and produces stronger transplants than direct-sown seedlings. This is the preferred method for spring kale in Pennsylvania because it lets you have plants ready to go into the ground as soon as the soil is workable — often 2 to 3 weeks before the last frost.

Indoor Starting Schedule by Zone

How to Start Kale Seeds Indoors

1. Fill cell trays or small pots with seed-starting mix (not garden soil). Moisten the mix until it feels like a wrung-out sponge. Standard 6-cell or 12-cell nursery trays work well.

2. Sow 2 seeds per cell at 1/4 inch depth. Press the seeds gently into the surface and cover with a thin layer of mix. Kale seeds are small — about 1/16 inch — so do not bury them deeply.

3. Keep soil temperature at 65 to 75 degrees for germination. A warm spot on top of the refrigerator or near a heating vent works. A seed-starting heat mat provides the most consistent temperatures. Expect sprouts in 5 to 7 days.

4. Move to bright light immediately after germination. Kale seedlings need 14 to 16 hours of light per day. A south-facing window in February provides only 10 to 11 hours of weak winter light, which produces leggy, weak seedlings. A shop light with full-spectrum bulbs hung 2 to 3 inches above the seedling tops is the reliable solution.

5. Thin to 1 seedling per cell once the first true leaves appear (the second pair of leaves, not the initial rounded cotyledons). Snip the weaker seedling at the soil line rather than pulling it — pulling disturbs the roots of the keeper.

6. Keep seedlings cool after germination. Daytime temperatures of 60 to 65 degrees and nighttime temperatures of 50 to 55 degrees produce the stockiest, hardiest transplants. Kale seedlings grown in warm rooms (70+) tend to be tall and floppy.

Direct Sowing Kale Outdoors

Direct sowing works well for fall kale and for spring plantings after the soil reaches 45 degrees Fahrenheit. The biggest advantage of direct sowing is simplicity — no indoor setup, no hardening off, no transplant shock. The trade-off is a later start in spring and the need to manage weeds around tiny seedlings during the first few weeks.

When Soil Temperature Matters

Kale seeds germinate across a wide range of soil temperatures (45 to 85 degrees), but the rate changes dramatically. At 60 to 65 degrees, seeds sprout in 5 to 7 days. At 45 degrees, the same seeds take 10 to 14 days, and germination rates drop. Above 85 degrees, many seeds will not germinate at all — which is why direct sowing fall kale into hot August soil often fails. The solution for fall plantings is to start seeds in cell trays in a shaded spot and transplant, rather than direct-sowing into sun-baked ground.

How to Direct Sow Kale

1. Prepare the bed as described in the soil prep section above. Rake the surface smooth so small seeds make good contact with the soil.

2. Create shallow furrows 1/4 to 1/2 inch deep, spaced 18 to 24 inches apart. Use the edge of a hoe or a stick pressed into the soil.

3. Sow seeds 1 inch apart along the furrow. Kale seeds are small, so taking a pinch and sprinkling them works better than placing them individually. You will thin later, so slight over-seeding is fine.

4. Cover with 1/4 inch of fine soil or seed-starting mix and press gently. Water with a gentle spray — a hard blast from a hose will wash seeds out of the furrow or bury them too deeply.

5. Keep the seedbed consistently moist for the first 10 to 14 days until germination is complete. In spring, PA’s natural rainfall usually handles this. In summer (for fall plantings), you may need to water lightly every day or every other day.

6. Thin seedlings to 12 to 18 inches apart once they have 3 to 4 true leaves. Use scissors to snip at the soil line. The thinnings make excellent baby kale for salads — do not throw them away.

Transplanting Kale Seedlings

Transplanting is the moment where weeks of indoor preparation either pay off or fall apart. Kale handles transplanting better than most brassicas, but skipping the hardening-off step or planting into unprepared soil will set your plants back by weeks.

Hardening Off: The 7-Day Process

Indoor-grown seedlings need to adjust to outdoor conditions gradually. Cold wind, direct sun, and temperature swings can shock seedlings that have only known the stable environment of your kitchen. Start the hardening-off process 7 days before your target transplant date.

Transplanting Step by Step

1. Water seedlings thoroughly 2 to 3 hours before transplanting. Moist root balls slide out of cells cleanly; dry ones crumble and damage fine feeder roots.

2. Dig holes slightly larger than the root ball — about 3 to 4 inches deep and 3 inches wide. Space holes 12 to 18 inches apart in rows 18 to 24 inches apart. Closer spacing (12 inches) works in fertile raised beds; wider spacing (18 inches) is better in native clay where plants need more room to access nutrients.

3. Set the seedling at the same depth it grew in the tray. Kale does not benefit from deep planting the way tomatoes do. Burying the stem invites rot, especially in PA’s wet spring soil.

4. Backfill, press firmly, and water deeply. Give each transplant at least one pint of water at the base right after planting. This collapses air pockets around the roots and ensures immediate soil-to-root contact.

5. Transplant on a cloudy day or in the evening. Full midday sun on freshly transplanted seedlings causes wilting even if the soil is wet. Overcast skies or late-afternoon planting gives roots several hours to start anchoring before the next day’s sun hits.

Watering Schedule and Technique

Consistent moisture is the key to tender, mild-tasting kale. Drought stress makes leaves tough and bitter. Overwatering in PA’s clay soil causes root rot and fungal problems. The target is 1 to 1.5 inches of water per week, delivered deeply and evenly.

Watering Method Comparison

Water in the early morning whenever possible. Morning watering gives leaf surfaces time to dry before evening, which reduces fungal disease pressure. Avoid watering in the evening, especially during PA’s humid June and July — wet foliage overnight is the fastest path to downy mildew on kale.

Seasonal Watering Adjustments

Spring kale in PA often needs minimal supplemental watering because April and May typically bring adequate rainfall. Check soil moisture by pushing your finger 2 inches into the ground — if it feels dry at that depth, water. During the summer months (June through August), kale needs more attention. Hot days with temperatures above 85 degrees can dry out the top few inches of soil in a single afternoon, especially in raised beds and containers. Increase watering frequency to every 2 to 3 days during heat waves.

Fall kale (September through November) needs less water as temperatures cool and evaporation slows. Reduce to watering every 4 to 5 days unless conditions are unusually dry. Once nighttime temperatures drop below freezing regularly, water only on days when the air temperature is above 40 degrees and the soil has thawed enough to absorb moisture.

Fertilizing for Continuous Leaf Growth

Every time you harvest kale leaves, the plant needs nitrogen to push out replacements. Without regular feeding, leaf production slows and remaining leaves turn tough and bitter. Kale is a heavy nitrogen feeder, and PA soils — even well-composted ones — cannot supply enough nitrogen to sustain continuous harvesting over a 4 to 6 month season without supplemental feeding.

Fertilizing Schedule

Mulching and Weed Management

Mulching is one of the most underused techniques in PA vegetable gardens, and research confirms that organic mulches improve both soil health and vegetable yields. Kale responds to mulching dramatically. A 2 to 3 inch layer of organic mulch around kale plants keeps soil moisture even, suppresses weeds, moderates root zone temperature through our daily temperature swings, and adds organic matter as it breaks down over the season.

Best Mulch Materials for PA Kale

Apply mulch after transplants are established (about 1 week after planting) or after direct-sown seedlings reach 4 to 6 inches tall. Pull mulch 1 to 2 inches away from the base of each plant stem to prevent moisture from collecting against the stalk, which can lead to stem rot in PA’s humid conditions.

For weed management, the mulch layer handles most of the work. Any weeds that push through should be hand-pulled while small. Avoid cultivating or hoeing within 6 inches of kale plants — their shallow feeder roots extend outward from the stem and are easily damaged by tools.

Pest Prevention Without Heavy Spraying

The most effective pest control for kale in Pennsylvania is prevention, not treatment. If you can stop pests from reaching your plants in the first place, you will never need to spray. The three pests that cause the most damage to PA kale are imported cabbageworms, aphids, and flea beetles — and all three can be managed with physical barriers and cultural practices.

Row Cover: The Single Best Defense

Draping a lightweight floating row cover over your kale immediately after transplanting is the most effective organic pest prevention method available. The fabric allows light and water through but blocks the white cabbage moths from landing and laying eggs on your plants. It also stops flea beetles from reaching seedlings and reduces aphid colonization by making the plants harder to find.

Since kale does not need pollination (you are harvesting leaves, not fruit), the row cover can stay on all season long. Support it on wire hoops at 12 to 18 inches above the plant tops so leaves do not press against the fabric and create landing spots for moths on the outside. Anchor the edges with stones, soil, or landscape staples to prevent wind from lifting it.

If Pests Get Through

For a complete guide to identifying and treating every kale pest and disease in Pennsylvania, including spray schedules, severity ladders, and prevention calendars, see our kale pests and diseases guide.

Succession Planting for Year-Round Kale

Succession planting means sowing new seeds or transplanting new seedlings at regular intervals so you always have kale at different stages of growth. Instead of one big planting that produces a glut and then fades, succession planting gives you a steady, moderate harvest from April through December.

Three-Sowing Succession Plan for PA

Running all three sowings gives you kale from May through February — about 10 months of the year. The spring planting carries you through early summer. The early fall planting handles September through December. The late fall planting, protected with row cover or a cold frame, produces small harvests through the coldest months and then bolts in spring, giving you edible flower buds (kale raab) before you pull the plants and replace with new spring transplants.

Extending the Harvest into Winter

Kale is one of the very few vegetables that lets you keep harvesting through a Pennsylvania winter without a heated structure. The key is getting plants to full size before the first hard freeze and then protecting them with simple, low-cost covers that trap enough warmth to keep the growing point alive.

Protection Methods Ranked by Effectiveness

The combination that works for most PA gardeners is straw mulch plus a single row cover on hoops. This setup costs under $30 for a 50-foot row, takes 30 minutes to install, and extends harvests through December in zones 6a through 7a. In zones 5a and 5b, add a second layer of row cover or upgrade to a low tunnel for the coldest months. For more details on overwintering and spring regrowth, see our kale growing hub.

Harvesting Techniques

How you harvest determines how long your kale plants keep producing. The cut-and-come-again method is the standard approach, and when done correctly, a single kale plant can yield 2 to 3 pounds of leaves over a full season.

Cut-and-Come-Again: The Right Way

1. Wait until plants have 8 to 10 full-sized leaves before your first harvest. Picking too early weakens the plant and delays future production.

2. Pick from the outside in. Always remove the lowest, oldest leaves first by snapping or cutting the stem where it meets the main stalk. New growth pushes from the center top, so leaving the inner leaves intact keeps the growth engine running.

3. Leave at least 5 to 6 leaves on the plant. This is the minimum foliage needed to sustain photosynthesis and root growth. Taking more than this forces the plant to recover from a deficit, slowing the next harvest cycle.

4. Harvest 3 to 5 leaves per plant every 5 to 7 days during active growth. This pace matches the plant’s ability to replace leaves and keeps your harvest continuous rather than feast-or-famine.

5. Harvest in the morning after dew dries but before the heat of the day. Morning-picked kale has the highest water content and crispest texture. Afternoon-picked leaves during summer can be limp and slightly bitter.

Full-Plant Harvest

If you are done with a planting (pulling spring kale before summer, for example), you can harvest the entire plant by cutting the main stem 2 inches above the soil line. The stump may resprout a small secondary crop of side shoots within 2 to 3 weeks. These side shoots produce smaller leaves but are very tender and perfect for salads.

Full-Season Task Timeline

Use this month-by-month reference to stay on track. Dates assume central PA (zone 6a); adjust 2 weeks earlier for zone 7a and 2 weeks later for zone 5a.

Plan your full season: See our monthly planting guide for a month-by-month schedule, or browse all crops in our Pennsylvania vegetables hub. For frost timing, check our PA frost dates by region.

Frequently Asked Questions About Growing Kale in Pennsylvania