What to Do in Your Garden in Late August | Late Summer Gardening Tips

Late August is an important time in the garden. The summer heat is still with us, but cooler weather is on the way. For gardeners in zone 7, this is the point where preparation meets transition—wrapping up the summer season while setting the stage for fall and even next spring.

If you’re in a warmer zone, you may have more time to complete these tasks. Cooler zones may need to move faster. Either way, most of these ideas can be adapted to your growing conditions.

Here are five key things to focus on in the garden at the end of August:

1. Take Cuttings of Perennials and Annuals

Late summer is still a good time to root cuttings. Many plants are actively growing, and propagating them now gives you a head start for next year.

• Perennials like salvia and rosemary can be rooted in a sand and coir mix. Rosemary benefits from well-drained but slightly moisture-retentive soil.
• Annuals such as coleus, basil, and lantana can be overwintered indoors by taking cuttings. This saves plants that won’t survive frost in zone 7.
• Remove lower leaves, trim back any blooms, and place cuttings into a moist rooting medium. Keep the container well-drained.

This is also a good time to take “insurance cuttings” of plants you don’t want to lose, like the rosemary, which can be temperamental in cold winters with damp locations.

2. Collect Seeds from Healthy Plants

Seed saving allows you to preserve plants that perform well in your garden and adapt them over time to your local conditions.

• Black-eyed Susans (Rudbeckia), basil, and other flowering plants can be collected once seed heads have dried.
• Choose plants that were disease-resistant or particularly productive to pass on those traits.
• Store seeds in a cool, dry place until spring planting.

By collecting seed from your strongest plants, you gradually develop a selection of varieties well-suited to your specific microclimate.

3. Divide Irises and Daylilies

Both irises and daylilies benefit from division every few years. Crowded clumps reduce flowering and overall plant health.

• Dig and divide now while the soil is still warm.
• Replant healthy divisions promptly so roots have time to establish before winter.
• Remove and discard any diseased or spotted foliage and avoid adding this material to your compost.

Dividing at this time of year ensures better flowering and stronger plants next spring.

4. Harvest and Preserve the Vegetable Garden

Preserving your harvest now ensures you can enjoy summer produce throughout the colder months.

• Peppers: Dry them in a dehydrator and grind into powder. Hot peppers should be dehydrated outdoors or in a well-ventilated space.
• Cucumbers: Pickling is an excellent way to extend the harvest.
• Tomatoes and other produce: Consider canning or freezing to store them long-term.

This is also a good time to begin planting a fall vegetable garden. Cool-season crops such as bok choy, kale, parsley, cilantro, mustard greens, and lettuces can be started now. They may slow down during the coldest part of winter but often resume growth in early spring.

For a more detailed list, see this article: 15 Plants to Start in August for Fall in Tennessee.

5. Plan for Fall Tree and Shrub Planting

Fall is the best time to plant most trees and shrubs. Cooler temperatures reduce stress on new plants, and roots continue to grow in the still-warm soil.

• Create a list now of the trees and shrubs you’d like to add, so you’ll be ready to plant in a few weeks.
• Protect young trees from deer damage, as bucks often rub their antlers on trunks in fall. Simple tree guards or fencing can prevent permanent injury.

Planting in fall allows trees and shrubs to establish strong root systems before spring growth begins.

Ongoing Care

Even though the weather begins to cool, plants still need regular attention:

• Watering: Monitor rainfall. Fall dry spells can stress perennials, vegetables, and young trees.
• Weeding: Stay on top of weeds so they don’t set seed and carry problems into next year.

Final Thoughts

Late August bridges summer and fall. By taking cuttings, saving seed, dividing perennials, preserving your harvest, and preparing for fall planting, you set your garden up for continued success. Small tasks now make a big difference in the health and productivity of your garden in the seasons ahead!