Spring is the time we usually associate with new beginnings. As the soil warms and the days grow longer, we can sow our seeds and watch as leaves unfurl and flowers bloom. A rush of activity sees us starting seedlings, turning over soil, mulching, and a host of other activities. But what if it’s better to start your garden in September instead?

While spring can be an invigorating time of renewal, it can also be unpredictable. It’s a good time for growing vegetables and starting annuals. However, late summer and early fall are more about establishing and sustaining the garden as a whole. 

The pace of the garden in the fall is slower. It’s more deliberate and focused on rejuvenation and preparation for the year to come. While spring gardening is a time for new beginnings, September is a time to lay foundations and nurture the garden as a whole. There are several factors that make September an ideal time to start a garden. Let’s discuss. 

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Starting a Garden in September

The reason September is an excellent time to start a garden has mostly to do with the weather. While spring is a nice time for enjoying the blooming garden, much of the foundational work is better carried out in the fall. 

Warm Soil

Perennials establish faster with soil holding summer warmth.

A primary factor that makes September a good time to start a garden is the soil temperature. By early fall, the ground has absorbed the warmth of summer. It holds that heat and remains consistently warmer than it does in early spring. Warm soil encourages rapid root growth, which is the foundation of healthy plants. 

Planting perennials, shrubs, or cool-season vegetables is ideal under these conditions. The warm soil helps to form strong roots. It enables them to anchor firmly, access nutrients, and prepare for winter dormancy. It also allows them to get an early start in the spring. 

In the spring, cold soil slows germination and root development. It’s fine to plant in spring once the soil warms up, but September’s warm soil gives new plantings a head start. Trees, shrubs, and other perennials will all establish faster, and that means they can focus on vigorous growth in the spring. 

Warm soil in September also provides a gentle growing environment with less stress. Seeds germinate more quickly, and transplants recover from shock faster. Perennials settle in with less risk of rot compared to wet, chilly spring soils. Warm fall soil creates the “sweet spot” where plants can focus on root establishment. 

Instead of fighting heat stress or racing to flower, your plants can focus their energy more effectively. This means vegetables sown in September often produce crisper, sweeter harvests. Perennials and shrubs planted now come back stronger and more resilient the following spring. 

Cool Air

Roots establish quickly when the air stays refreshingly cool.

The cool air of September paired with the warm soil creates excellent conditions for a fall start in the garden. The intense heat of summer is stressful on plants, especially young and newly planted ones. Gentler daytime temperatures in September help plants establish more easily. 

Cooler air also means less evaporation. The soil stays evenly moist for longer, and plants require less frequent watering. This is most important for seedlings, transplants, and new perennials, as they are vulnerable to drying out. 

Cooler air also improves the quality and flavor of many crops. Leafy greens, such as spinach, kale, lettuce, and arugula, thrive in the cooling fall air. This is an interesting phenomenon that happens as a result of a survival mechanism. When the temperature drops below freezing, these leafy green plants convert stored starches into sugar. The byproduct of this is a noticeably sweeter flavor. 

Many root vegetables, such as carrots, radishes, and beets, also improve with cold weather. They grow more tender and flavorful. The mild autumn air helps newly planted trees, shrubs, and other perennials focus on building strong root systems. In summer, they tend to divert that energy into coping with heat. 

Warm soil combined with cool air creates a perfect balance. Plant roots grow quickly below ground, while foliage above doesn’t have to endure the stress of scorching sun and high temperatures.

Increased Rainfall

Deep roots form best in evenly moist soil.

In many regions, summer is typically a drier season. Between decreased rainfall and heat, plants become parched in soil that dries faster due to evaporation. Fall often brings increasingly consistent rain. This leads to reduced transplant shock and encourages deeper root growth, anchoring your plants firmly. 

Consistent moisture also helps seeds to germinate faster. It’s advantageous in getting your cool-weather crops off to a strong start. You’ll get a more successful germination rate for many of these crops than you would in the spring. 

The reason rainfall makes fall better than spring for this purpose connects with the other factors. Coupled with warm soil, all that rain creates an ideal environment for germinating seeds and establishing roots. The combination of factors makes September a productive and forgiving time to start planting.

Fewer Pests and Diseases

Many insects die off before the cooler season.

Reduced pests and diseases is another excellent reason to start a garden in September. This month, there are fewer pests and diseases in the garden. Many of the insects and pathogens that thrive in summer decline. This happens as a result of the shorter days and cooling temperatures. 

Most garden pests, like aphids, whiteflies, and spider mites, multiply rapidly in warm, dry conditions. In September and October, the weather conditions naturally cause their populations to slow down. 

Many insect species complete their life cycles by late summer. The adults die off, and the eggs go dormant until spring. This is great news for gardeners because it means fewer active pests to attack young fall crops. 

Cooler nights also make it more complicated for certain fungal diseases to spread. Those that favor heat and humidity begin to abate, which eases problems like powdery mildew or blight. The decline in pests and diseases gives the gardener more time to work on growing rather than controlling. 

September Gardening Tasks

Pull spent plants and clean up dead material.

Here are some of the many things you can start in the garden in September. 

Plant and Divide	Plant spring-flowering bulbs Divide and replant perennials Plant trees, shrubs, and herbaceous perennials Start cool-season crops Sow seeds that need cold stratification
Soil and Bed Care	Pull weeds Amend soil with compost or other nutrient-rich materials Plant cover crops to prevent erosion and enrich the soil Mulch beds
Maintenance	Pull spent annuals Remove dead and diseased plant material Cut back some perennials (leave seed heads of others) Clean up leaves and put them in piles for overwintering insects and composting
Protecting and Preparing	Maintain irrigation and winterize Protect young or sensitive plants with mulch, row covers, etc. Start to protect or relocate frost-tender container plants