Essential Gardening Tasks for August

As August unfolds, gardens become vibrant with a continuous supply of fresh produce. This month is ripe for harvesting tomatoes, cucumbers, beans, and zucchini. Fruits like plums and early apples also reach maturity, while blackberries darken on the vine. Summer flowers remain lively, showing no signs of autumn just yet. However, as the days gradually shorten, the garden begins to shift, with morning dew becoming a common sight and some plants starting their preparations for fall. While the focus remains on watering, harvesting, and tidying, some tasks for the upcoming season can also be initiated without overwhelming effort.

Weather – Heat, Thunderstorms, and Cooler Nights

August can bring prolonged periods of heat and dryness. Rainfall may not sufficiently penetrate the soil to reach the roots, so it's important to check moisture levels not just at the surface but a few inches below. Ideally, watering should be done early in the morning. If that’s not feasible, evening watering is acceptable. Ensure water is delivered directly to the roots rather than on the leaves, flowers, or fruits. Plants such as tomatoes, cucumbers, zucchini, beans, pumpkins, young plants, raised beds, and container plants require consistent moisture.

Signs and Measures

| Signs | Meaning | Action | |-------|---------|--------| | Leaves droop only during midday heat | Possible heat reaction | Check soil; water only if dry | | Soil is dry beneath the surface | Water shortage | Water the root zone thoroughly | | Water runs off the surface | Soil is severely dry | Water slowly in multiple passes | | Tomatoes or other fruits split | Inconsistent watering | Water evenly and regularly | | Fresh seed rows dry out | Germination at risk | Keep soil gently moist | | Containers or tall plants are unstable | Risk of storm damage | Support, weigh down, or place in a sheltered spot |

A layer of mulch made from dried grass clippings, leaves, straw, or other suitable materials helps retain soil moisture while protecting the surface from overheating and compaction. It’s also important to avoid using ice-cold water, as it can shock plants. Instead, use room-temperature water collected from a rain barrel.

Ornamental Garden – Maintain Blooms and Collect Seeds

In August, dahlias, coneflowers, asters, phlox, sunflowers, and other plants create colorful beds. To encourage further blooming in annual summer flowers, roses, and repeat-flowering perennials, regularly remove spent flowers. However, not every flower head needs to be cut off. If you wish to collect seeds or allow certain plants to self-seed, leave some healthy seed heads to mature. This is particularly suitable for plants like columbine, marigold, foxglove, hollyhock, poppy, and cosmos.

Tall perennials, dahlias, gladiolus, and sunflowers will continue to need support. Check existing stakes and ties, as growth may have caused them to become too tight or the stems to bend over.

Additional tasks for the ornamental garden include:

• Lightly trimming lavender after flowering, if not already done.
• Removing broken stems after a storm.
• Clearing away diseased or rotting leaves from dense perennials.
• Trimming aggressively growing ground covers at bed edges.
• Continuing to shield newly planted specimens from intense midday sun.
• Harvesting seeds when dry and labeling them with the plant name and year.

In hot, dry weather, postpone major planting and dividing tasks. Towards the end of August, you can divide hardy perennials when temperatures drop and watering can be reliably managed.

Autumn Bloomers – Planting Bulbs

When considering bulbs, thoughts often turn to tulips and daffodils, which can be planted a bit later. However, August is the time to plant bulbs and tubers that will bloom in the fall. These include:

• True saffron
• Autumn crocuses
• Autumn snowflake
• Gold cup

Plant bulbs soon after purchase, ensuring the soil is loose and well-drained to prevent waterlogging. The planting depth and spacing depend on the type. Be cautious with autumn snowflakes, as all parts of the plant are highly toxic. Wear gloves while planting and avoid confusing it with the edible true saffron.

Hedges and Shrubs – Limit New Growth

In August, only gentle shaping and maintenance cuts are advisable for hedges. Significant pruning, removals, and severe reductions should be postponed. Before making any cuts, check for nesting birds, as late broods may still be present.

Additionally, this month marks the time for the second cut of wisteria. Long side shoots should be trimmed back to about five to seven leaves, while the strong main shoots that form the plant's framework should remain intact. Check trellises and supports for other climbing plants. Clematis, grapevines, and climbing roses can loosen fixtures from walls due to their weight and strong winds.

Roses and Container Plants – Differentiating Fertilization

Continue to deadhead repeat-flowering roses, cutting spent blooms above a well-developed leaf. If you wish to have rose hips in the fall, leave some flower heads intact on suitable varieties. Collect diseased leaves showing signs of black spot, rose rust, or other noticeable blemishes. Fallen leaves should not remain under the plants, and heavily diseased leaves should not go on the compost.

Annual summer flowers in containers and boxes can still receive fertilizer as long as they are growing vigorously and blooming. However, roses, shrubs, and overwintering container plants should not be fertilized with nitrogen-rich products after mid-August, as new shoots may not mature adequately before winter.

Container plants tend to dry out faster than those in the ground, so check larger and densely rooted pots regularly. Remove any water that has been sitting in the saucer for an extended period.

Fuchsias and geraniums can be propagated through cuttings now. Cut healthy stem tips, remove the lower leaves, and place the cuttings in seedling soil. Keep the soil evenly moist but not soggy.

Fruits and Berries – Harvesting, Pruning, and Planting Strawberries

The fruit garden is bustling in August. Depending on the variety and region, plums, mirabelles, peaches, early apples, pears, blackberries, blueberries, autumn raspberries, and the first grapes ripen. Regularly pick fruits and remove any damaged ones. Fallen fruit should not be left under trees for long, as it attracts wasps, can promote diseases, and create slippery spots on paths. Healthy fallen fruit should be processed promptly.

Apples are ready to be picked when they easily detach from the branch with a gentle twist. Pears, depending on the variety, are often harvested before they become fully soft on the tree.

For heavily laden fruit trees, continue to monitor the branches. Plum trees, in particular, can break under the weight. Support any at-risk branches without damaging the bark with narrow supports.

Cut back summer raspberry canes at ground level after harvesting. The young canes should remain and be loosely tied. Autumn raspberries bear fruit on this year’s canes and should not be cut back now.

New strawberry plants should ideally be planted by mid-August to allow ample time for strong root development for the following year. Ensure the crown of the plant is not buried in soil.

Vegetable and Raised Beds – Harvest and Replant

August yields a bountiful harvest of tomatoes, cucumbers, zucchini, beans, Swiss chard, peppers, eggplants, salads, carrots, and beets. Regularly check cucumbers and zucchini; if fruits are left too long, they grow large and the plants produce less.

Continue to tie up tomatoes and remove suckers from determinate varieties. Remove sickly and low-lying leaves. However, a radical clearing of foliage is not advisable, as leaves protect the fruits from intense sunlight. By the end of August, you can remove the growing tip of tall indeterminate tomatoes if many green fruits are already present, as late blooms often lack sufficient time to ripen in the open ground.

Harvest onions and garlic once the foliage naturally yellows and bends. Do not intentionally press the leaves down to the ground. After harvesting, allow onions and garlic to dry in a dry, airy place.

Place boards, flat stones, or straw under pumpkin fruits to keep them off moist soil and reduce the risk of rot.

Free beds should not remain uncovered in August. Either sow and plant autumn vegetables or apply a green manure crop. This helps retain soil moisture and prevents quick colonization by weeds.

Cold Frames and Greenhouses – Avoiding Excess Moisture

On sunny days, greenhouses can reach very high temperatures. Therefore, doors, windows, and ventilation flaps should be opened in the morning. In strong sunlight, shading remains beneficial.

Continue to harvest tomatoes, cucumbers, peppers, and eggplants, tying them up as needed. Remove yellowing, diseased, and dead leaves. Water in the morning directly onto the soil and ventilate thoroughly afterward. Humid nights and increased dew in late summer raise the risk of fungal diseases. Therefore, it’s crucial to keep tomatoes as dry as possible. If you spot brown spots on leaves or fruits, remove the affected plant parts immediately.

Heavily diseased crops should not be left unnecessarily long. Clear them out and use the freed space for autumn salads, spinach, or lamb’s lettuce. The cold frame is suitable for protected sowing in August. On warm days, keep the cover open or propped up to prevent heat buildup underneath.

Sowing and Pre-Growing in August – Preparing for Autumn

August is primarily focused on crops that grow quickly or can be harvested in the fall and winter. The exact timing depends on the variety, region, and weather, so also refer to the instructions on the seed packet. In hot weather, fine seed rows can dry out quickly. Water the area thoroughly before sowing and keep the soil consistently moist afterward. A breathable cover can protect against drying until germination.

Indoors for Pre-Growing

• Kohlrabi
• Head lettuce
• Winter head lettuce

Directly in the Bed

• Asian salads
• Lamb's lettuce
• Cress
• Radishes
• Radish
• Arugula
• Spinach
• Winter onions

Planting

• Chinese cabbage
• Endive
• Kale
• Kohlrabi
• Leeks
• Pak choi
• Radicchio
• Salads
• Sugarloaf

When it comes to herbs, you can sow dill, chervil, cress, parsley, and chives. Parsley germinates slowly and should not be allowed to dry out during this period.

Flowers are also still an option for biennial species. Early August is a good time to sow sweet william, foxglove, wallflower, pansies, hollyhocks, and forget-me-nots. They will develop leaves this year and bloom in the following year.

A comprehensive overview can be found in our garden blog as standalone posts regarding vegetable, herb, and flower sowing in August.

Lawn, Paths, and Watering – Preventing Damage

During dry spells, continue to mow the lawn at a higher setting. Cutting too short can expose the soil to damage. Regularly check paths and ensure they remain clear to avoid slipping hazards. Adjust watering practices to maintain healthy growth without causing further stress to the plants.