Swiss Chard in Zone 5A — Great Plains

Swiss chard is a workhorse in the Great Plains garden. It shrugs off the summer heat better than spinach, gives you gorgeous, colorful leaves, and keeps producing from early summer right up until those first frosts threaten. Plus, that slightly earthy flavor is fantastic sauteed, in soups, or even raw in salads.

Our extreme weather can be a challenge, but Swiss chard is surprisingly resilient. With a little planning, you can easily fit in a couple of harvests during our 168-day growing season, even with those unpredictable temperature swings we're known for.

Starting Swiss chard indoors isn't essential, but it can give you a head start, especially if you're eager for an early harvest. Start your seeds indoors from late March through mid April, about four weeks before you plan to transplant them outside. Use seed trays with a good seed-starting mix and keep them warm, around 70°F, until germination.

A simple setup with a grow light will ensure strong seedlings. Make sure to bottom water to avoid damping off. Given our variable spring weather, indoor starting can be a good insurance policy against a late cold snap.

Transplant your Swiss chard seedlings outdoors from late April through late May, once the danger of hard frost has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the wind and sun.

Space the plants 8-12 inches apart in well-drained soil. Keep an eye on the forecast; an unexpected cold snap can still happen this time of year, so be prepared to cover your young plants if needed.

Direct sowing Swiss chard is a simple and effective way to grow it in the Great Plains. Sow seeds mid April through early August for a continuous harvest. Prepare a bed with well-draining soil and make sure the soil temperature is at least 50°F.

Plant seeds about ½ inch deep, spacing them 8-12 inches apart. Direct sowing is less work than starting indoors, but remember that germination can be slower if the soil is too cold or dry, especially during those early spring temperature swings.

Swiss chard needs consistent moisture, but it doesn't like to be waterlogged. In the Great Plains, with our hot summers and variable rainfall, getting watering right is key. During the hotter months, you'll likely need to water deeply about 1-2 times per week, providing about 1 inch of water each time.

Stick your finger about 2 inches into the soil near the base of the plant. If it feels dry, it's time to water. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our low-to-moderate humidity.

Wilting leaves are a sign of underwatering, while yellowing leaves can indicate overwatering. A layer of mulch around your plants helps retain moisture and regulate soil temperature, which is especially helpful during our extreme temperature swings.

You can expect your first Swiss chard harvest in early June through mid October, about 55 days after planting. Look for outer stalks that are 8-12 inches tall. The colorful stems – red, yellow, or white – are perfectly edible and add a nice visual touch to your dishes.

To harvest, simply cut the outer stalks near the base of the plant with a sharp knife, leaving the inner leaves to continue growing. This encourages continuous production throughout the season. As the first frost approaches in early October, harvest any remaining mature leaves to enjoy before the cold sets in.

Here are some common problems you might encounter with Swiss chard in the Great Plains:

Leaf Miners

• What it looks like: Squiggly, pale tunnels inside the leaves.
• What causes it: Small flies lay eggs on the leaves, and the larvae tunnel inside to feed. Hot weather can accelerate their life cycle.
• How to fix/prevent it: Cover plants with row covers to prevent the flies from laying eggs. Remove and destroy affected leaves. Encourage beneficial insects like parasitic wasps.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects. Populations explode in warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer (it attracts them).

Cercospora Leaf Spot

• What it looks like: Small, circular spots on leaves that eventually enlarge and turn gray or brown.
• What causes it: A fungal disease that thrives in warm, humid conditions. While our humidity is generally low, prolonged wet periods can create favorable conditions.
• How to fix/prevent it: Remove and destroy affected leaves. Improve air circulation around plants. Avoid overhead watering. Apply a copper-based fungicide if necessary.

Slugs

• What it looks like: Irregular holes in leaves, especially low-growing plants. Silvery slime trails on leaves and soil. Damage worse at night and in wet weather.
• What causes it: Gastropods that feed at night in moist conditions. Hide under mulch, boards, and debris during the day.
• How to fix/prevent it: Beer traps (shallow dish of beer sunk into soil). Iron phosphate bait (pet-safe). Remove hiding spots. Water in morning so soil surface dries by evening. Copper tape around beds. Diatomaceous earth around plants.

Great Plains Specific Challenges: Our combination of hot heat, low-to-moderate humidity, and variable rainfall can stress Swiss chard. Consistent watering is crucial to prevent bolting (going to seed prematurely). Wind protection is also essential to prevent leaf damage and dehydration.

Companion planting can help your Swiss chard thrive. Lettuce is a good companion because it provides ground cover, helping to keep the soil cool and moist. Onions and garlic deter pests like aphids. Green beans fix nitrogen in the soil, benefiting the chard. Cabbage family members also do well planted alongside Swiss chard.

Avoid planting Swiss chard near corn or potatoes. Corn competes for nutrients and water, while potatoes are susceptible to similar diseases that can affect Swiss chard.