What to Plant in June: Your Summer Microgreens Growing Guide

Quick answer: June heat doesn't have to slow down your microgreens growing — you just need the right varieties. Sunflower, amaranth, buckwheat, and basil microgreens all thrive in summer temperatures between 75-85°F, with sunflowers ready to harvest in as little as 7-9 days. Skip pea shoots and cilantro until fall, since they turn bitter and stringy once temps climb above 75°F.

June in Milton brings 85°F days and humidity that can make your growing trays feel like a greenhouse — even indoors.

Most microgreen varieties struggle when temperatures climb above 75°F, but some actually prefer the warmth. The trick is matching your seed choices to summer conditions while managing the extra moisture in the air.

Heat-Tolerant Varieties for June Planting

Sunflower microgreens handle summer heat better than almost any other variety. They germinate reliably at temperatures up to 80°F and actually grow faster in warm conditions — usually ready to harvest in 7-9 days versus 10-12 in cooler weather.

Amaranth thrives in June heat. The seeds germinate at 75-85°F, making them perfect for our Georgia summers. Their deep red stems and leaves add color to summer salads when other greens might wilt.

Buckwheat offers another heat-friendly option. These triangular-leaved microgreens prefer temperatures between 70-80°F and maintain their crisp texture even when grown in warm conditions.

Basil microgreens love summer warmth. While regular basil takes weeks to mature, microgreen basil delivers intense flavor in just 14-16 days when grown at 75-80°F.

Varieties to Avoid in Summer Heat

Pea shoots become stringy and bitter when grown above 75°F. Save these for fall and winter growing when you can maintain cooler temperatures.

Cilantro bolts quickly in heat, turning bitter before you can harvest the tender leaves. The seeds also have poor germination rates when temperatures exceed 75°F.

Most brassicas — including broccoli, kale, and cabbage microgreens — struggle in summer heat. They prefer temperatures between 60-70°F and often develop a sharp, unpleasant flavor when grown warmer.

Managing Summer Growing Conditions

Your biggest challenge in June isn't just temperature — it's humidity. North Georgia's summer humidity can push indoor levels above 70%, creating perfect conditions for mold and damping-off disease.

Run a dehumidifier in your growing space to keep humidity below 60%. This single change prevents more crop failures than any other summer adjustment.

Position your growing trays away from south-facing windows. Even indirect sunlight through glass can push tray temperatures into the 90s, killing seeds before they germinate.

Water less frequently but more thoroughly. Summer heat makes soil dry faster, but higher humidity means water doesn't evaporate as quickly from the surface. Check soil moisture with your finger before watering.

Use a small fan to improve air circulation around your trays. Moving air helps prevent fungal issues and keeps leaf temperatures closer to ambient room temperature.

Step 1: Adjust Your Seed Density

Plant summer varieties 25% less densely than winter crops. Heat-stressed plants need more space for air circulation. For sunflower microgreens, use about 1 ounce of seeds per 10×20 inch tray instead of the typical 1.3 ounces.

Step 2: Modify Your Germination Setup

Skip the blackout period for heat-sensitive varieties. While most microgreens benefit from 2-3 days in darkness, summer heat can turn a covered tray into an oven. Check your trays daily and remove covers as soon as you see green shoots.

Step 3: Time Your Harvests Earlier

Harvest summer microgreens 1-2 days earlier than usual. Heat accelerates growth but can also trigger early flowering or bitter flavors. Amaranth microgreens are particularly prone to this — harvest them as soon as the first true leaves appear.

Seasonal Advantages of June Growing

Summer's longer daylight hours actually benefit microgreen growth once you manage the heat. Most varieties develop more intense flavors when grown with 14+ hours of natural light.

The warm soil temperatures that challenge some varieties help others germinate faster. Sunflower seeds that might take 3-4 days to sprout in winter often germinate in just 24-48 hours during June.

Planning Your Summer Succession

Plant new trays every 5-7 days instead of the typical weekly schedule. Summer's faster growth means you'll harvest more frequently, and the shorter growth cycle helps you avoid the worst heat waves.

Keep notes on which varieties perform best in your specific growing space. Every setup handles summer heat differently — what works in a basement growing room won't necessarily work in a spare bedroom.

By August, you can start planning your fall transition back to cool-weather varieties like pea shoots and brassicas. But for now, embrace the summer heat and grow what thrives in these conditions.

June's challenges teach you more about microgreen growing than any other month. Once you master summer production, you'll handle every other season with confidence.

Keep Reading

• Microgreens 101: Everything You Need to Know
• Explore All Microgreen Varieties (Plant Database)
• Recipe: Sunflower Microgreen Salad
• Recipe: Microgreen Pesto

Timing Your Plantings Around June's Heat Curve

June in North Georgia doesn't stay at a steady 85°F all day. Temperatures typically climb from the mid-60s overnight to peak heat between 2–5 PM, then drop again after sunset. You can use that daily rhythm to your advantage.

Start germination in the evening. Seeds placed under a blackout dome at 7 or 8 PM will spend their first 10–12 hours in cooler, more humid air — conditions that encourage even germination without the stress of midday heat. By the time temperatures climb the next afternoon, your seeds are already anchored and pushing down roots.

Harvest in the morning. Microgreens cut before 10 AM have lower internal temperatures and higher water content than those harvested at noon. They store better, wilt slower on the plate, and taste crisper. This isn't a small difference — a sunflower flat harvested at 8 AM versus 2 PM can have noticeably different shelf life, sometimes by a full day.

For succession planting, stagger your trays every 2–3 days rather than weekly. June's warmth speeds up growth cycles, so a 7-day interval that worked fine in April will leave you with either a glut or a gap by mid-June. Two to three days between plantings keeps supply steadier.

A Simple June Planting Schedule

• Days 1, 4, 7: Sunflower (harvest at days 8–10 from each planting)
• Days 1, 7: Buckwheat (harvest at days 9–11)
• Day 1: Basil (harvest at days 14–16 — slower, so one planting per week is enough)
• Days 1, 5, 9: Amaranth (harvest at days 10–14, depending on how large you let it run)

This rotation gives you something ready to cut almost every other day through the month without overwhelming your growing space.

Variety-Specific Notes for Summer Growing

The broad categories — sunflower, amaranth, buckwheat, basil — are a good starting point, but within each there are details worth knowing before you fill your trays.

Sunflower

Black oil sunflower seed (BOSS) is what most growers use, and for good reason: it germinates uniformly, has a high hull-release rate, and handles heat without getting leggy. Striped sunflower seed is available but tends to produce thicker, more fibrous stems and a slightly lower germination rate — fine for home growing, but not ideal if you're trying to sell a consistent product.

Soak sunflower seeds for 8–12 hours before planting in summer. The hull softens enough that the seedling can shed it more easily, which matters more in warm weather when growth is faster. A seed that can't shed its hull in time becomes a stuck, bent seedling — edible but ugly. Soaking cuts that problem significantly.

Seed density matters more in June than in cooler months. If you pack trays too tightly, the canopy closes before stems can dry between waterings, and you'll see mold start at the base. Pull back to about 1.5–2 oz of seed per standard 10×20 tray rather than the 2–2.5 oz you might use in winter.

Amaranth

Amaranth is a genuine summer crop — it evolved in hot climates and behaves accordingly. The seeds are extremely fine, almost like dust, which catches new growers off guard. Mix them with a small amount of dry sand or vermiculite before spreading to get more even distribution across the tray.

Don't expect amaranth to look like sunflower or buckwheat. The seedlings are small and delicate, and they grow more slowly in their first few days before accelerating. At day 5, you might think something went wrong. By day 10–12, you'll have a dense, jewel-toned flat with deep magenta and green leaves.

Amaranth also holds in the tray longer than most summer varieties. If you're not ready to harvest at day 10, it can comfortably go to day 14 without getting bitter or tough — useful when you have a busy week and need some scheduling flexibility.

Buckwheat

Use unhulled buckwheat groats — the ones with the dark, angular hull still on. Hulled buckwheat won't germinate. This is one of the most common mistakes beginners make when ordering buckwheat seed for the first time. The hull is part of what anchors the seedling as it pushes up.

Buckwheat is also one of the few microgreens that benefits from bottom watering almost exclusively in summer. Top watering in humid conditions increases the chance of the wide, flat leaves staying wet long enough to develop gray mold. Set the tray into a shallow container with an inch of water and let the growing medium wick it up from below. Takes about 20 minutes, then remove and let drain.

Basil

Basil microgreens are slower than the others on this list and need a little more attention to moisture during germination — the seeds form a mucilaginous coating when wet, which helps them stay in place on the growing medium but can also cause them to clump if you're not careful when spreading. Sprinkle, don't pour.

Genovese basil is the standard variety and works well as a microgreen. Lemon basil and Thai basil also grow reasonably well at the microgreen stage and produce distinctly different flavors — lemon basil has a citrus brightness, Thai basil brings anise notes. If you're growing for your own kitchen, they're worth experimenting with alongside the standard Genovese.

Keep basil under the blackout dome a day longer than you think necessary. Rushing it into light too early in summer, when ambient temps are high and the dome is trapping heat, can cause the seedlings to stretch and flop. A full 4–5 days under cover, even if you can see green through the dome, produces sturdier plants.

Honest Caveats About Summer Growing

Summer microgreens aren't harder to grow, but they're less forgiving. A mistake that costs you a tray in February — overwatering, poor air circulation, seeds planted too densely — costs you two or three trays in June because problems compound faster in the heat.

Mold is the main issue. It's not a sign that you're doing something fundamentally wrong; it's a sign that one variable tipped out of balance. When you see it, don't throw the whole tray and give up — identify what happened. Was the humidity in the room above 65%? Did you water from the top two days in a row? Were the seeds too crowded? Fix the one thing and your next tray will likely be fine.

Some crops genuinely aren't worth fighting in June. Radish microgreens — one of the easiest crops in cooler months — can get a hot, harsh bite in summer heat that most people don't enjoy. You can grow them, and they'll germinate fine, but the flavor often isn't what you're expecting. If you're growing for customers or farmers market sales, save radish for September.

Indoor temperature control matters more than any single technique. If your growing space consistently runs above 82°F, even heat-tolerant varieties will underperform. A window AC unit or a growing space that stays naturally cooler — a basement, an interior room — makes more difference than any seed-soaking trick or watering method. Get the environment right first, then fine-tune everything else.

Notes from a Working Farm: What June Actually Looks Like

At Wind River Greens, June means reconfiguring our growing space. We move trays away from the east-facing wall where morning sun comes in strong after 7 AM. We run our dehumidifier on a timer — on from 6 AM to 6 PM, off overnight when outdoor humidity drops and the unit would just be cycling unnecessarily.

We cut sunflower volume back slightly in June, not because demand drops but because turnaround is faster and we've learned that trying to maintain the same number of active trays as winter leads to bottlenecks at harvest. Faster growth sounds like a benefit, and it is — until you have four trays all peaking on the same Tuesday morning.

We also lean into amaranth more heavily in June than any other month. It photographs well, it holds up in summer heat on a farmers market table better than most varieties, and customers who've never tried it are always curious about the color. A flat of red amaranth next to a flat of sunflower makes for a visually interesting table display that practically explains itself.

The most useful thing we've figured out over a few summers of doing this: check your trays in the evening, not just in the morning. Evening checks catch problems — a tray that's too wet, a patch of mold just starting, seeds that need the blackout dome removed — before they have all night to get worse. Five minutes of looking at your trays after dinner has saved us more crops than any product or technique we've tried.