BLog

August is the month of transition. Summer is waning. Fall is waiting in the wings. The garden is at peak production — tomatoes ripening daily, herbs flourishing, flowers blooming their hearts out. But August is also the moment to start preparing for what’s coming next.

The heat is still intense, which makes timing crucial. Some things must happen now — dividing iris, planting fall vegetables, preparing for autumn. Other things should wait until cooler weather arrives. August is about knowing the difference.

Here’s everything you need to do this month to keep your garden thriving through summer’s end and set yourself up for a spectacular fall.

GARDEN: Peak Production & Fall Preparation

Direct Sow Fall Vegetables By Mid-August

The window for direct sowing fall vegetables closes fast. By mid-August, soil is still warm enough for seeds to germinate, but you need enough time for crops to mature before the first frost (typically around October 10 in the Twin Cities).

Direct sow these now:

• Radishes: fastest, 25 days to harvest
• Arugula: 40 days
• Spinach: 40 days
• Lettuce: 45 days
• Beets: 55 days
• Kale: 55 days
• Carrots: 70 days

Before you plant: Pull out plants that are done producing — exhausted tomato plants, finished peas, anything that’s stopped producing. This opens space for fall crops and reduces pest habitat.

Plant Late-Season Perennials for Pollinator Support

August is a good time to plant perennials that bloom late summer through fall. These are critical for pollinators preparing for migration and for extending your garden’s blooming season.

Late bloomers to plant now:

• Sedum: blooms late summer through fall, drought-tolerant
• Turtlehead: blooms late summer, loves shady moisture, native varieties
• Aster: fall bloomer, pollinator magnet, native varieties
• Anemone: late summer to fall blooms, native varieties
• Goldenrod: late summer blooms, often blamed for allergies it doesn’t cause, native varieties

Water new plantings regularly during establishment. Mulch to retain moisture and keep soil cool.

Deadhead for Another Wave of Blooms

Salvia, rudbeckia, and coneflowers are still blooming, but you need to deadhead to keep the show going. Removing spent blooms signals the plant to produce more flowers instead of setting seed.

Deadhead every few days for maximum bloom production through September.

Fertilize Heavy Feeders Early August

Early in August, give tomatoes, peppers, and other heavy feeders a dose of fertilizer to support late-season growth. They’re still producing, and they’re hungry. Use a balanced or vegetable-specific fertilizer. Feed once early August, then let them finish the season on their own.

Transition Container Gardens to Fall

Many of your spring and summer annuals are tired or done blooming by late August. This is the time to refresh containers for fall. Replace crispy, spent, or struggling annuals with fall-blooming plants — ornamental grasses, celosia, colorful foliage plants, mums.

Add seasonal accents — branches, fall-colored foliage. Think about color schemes that transition into autumn. Late August container redesigns give you fresh, beautiful displays for fall entertaining and outdoor living.

Harvest Vegetables Regularly

Harvest tomatoes, peppers, and cucumbers every 1–2 days. Regular harvesting keeps production high. The more you pick, the more the plant produces.

Leaving ripe fruit on the plant exhausts it and invites pests. 

Best Time to Divide Bearded Iris & Peonies

August is the prime window for dividing these perennials.

Bearded Iris: Divide in early August after blooms fade. The plant needs time to establish before winter. Divide every 3–4 years to keep plants vigorous.

Peonies: Divide in late August (after mid-month). Peonies are finicky — they prefer to be divided every 5–7 years, and they need a few weeks to establish before frost.

Perennials That Are Done Blooming: As other perennials finish blooming for the year, they can be divided. Spring bloomers especially benefit from division in late summer — they’ll establish before winter and return stronger next year. Hostas, daylilies, and other summer bloomers can also be divided now.

Watch for Pests and Act Quickly

August is peak pest season. Tomato hornworms, Japanese beetles, and aphids are all active.

Scout your garden every few days. If you spot pests, address them immediately. Handpick (tomato hornworms), spray with insecticidal soap (aphids), or use targeted treatments. Early intervention prevents infestations from exploding.

Start Thinking About Spring Bulbs

Fall is bulb planting season (October–November), so start thinking now about what you want to plant. Tulips, daffodils, crocus, hyacinths — what will make your spring garden sing?

Make a list, note varieties you like, and plan where they’ll go. This gives you time to visualize your spring before planting starts.

HOME: Bringing Plants In

Watch for 50°F Overnight Lows

Even though it’s still August, Minnesota nights can dip to 50°F — the threshold where tropical houseplants start to suffer cold stress. When the forecast shows overnight lows at 50°F or below, bring houseplants inside. You can move them back outside during warm days, but nighttime temperature matters. This is usually a mid-to-late August concern, but check the forecast regularly.

Fertilize Houseplants Before Winter Slows Them Down

August is a great window to fertilize houseplants before you need to slow down feeding for winter (most houseplants need minimal feeding November–February). Give them a balanced fertilizer to support their final growth push before the shorter days slow their metabolism.

After September, hold off on fertilizing until spring.

LANDSCAPE: Planting & Lawn Care

Start Applying Lawn Seed Late Month

Late August is the start of the best time of year for lawn care. Soil is still warm, nights are cooling, and fall moisture helps seed germinate. If you’re overseeding or starting new lawn, late August through September is prime time. Water newly seeded areas regularly until grass is established.

Great Time to Plant Shrubs and Trees

August and September are excellent for planting shrubs and trees. The soil is warm (helping roots establish), and fall moisture supports growth.

Plant new shrubs and trees with: Good soil preparation, proper planting depth, and thorough mulching (2–3 inches around the base, away from the trunk). Mulch is especially important with late-season heat still present. Water newly planted shrubs and trees regularly through fall.

The August Mindset

August is productive and transitional. Peak summer production is happening — harvest it. But also prepare for what’s coming.

Plant fall crops. Divide iris and peonies. Plant shrubs and trees. Refresh containers. Fertilize houseplants. Transition to fall colors and designs.

August is about honoring summer’s end while building momentum for autumn. Embrace it!