The days are getting shorter. It’s finally fall, and there are pumpkins on all your neighbors’ doorsteps. The gardening season is over, right? Think again! Even in colder zones where frost is imminent, there are plenty of ways to enjoy gardening in September.
Not only is this a crucial time to prepare for winter and next year’s growing season, but it’s also not too late to start growing crops and ornamentals right now, such as cold-weather greens, chrysanthemums, and even cover crops.
If you’re looking for inspiration as the days get chillier, we’ve assembled a list of ways to make September the best month in the garden.
Divide and Transplant Perennials
Move perennials in September to give them enough time to grow roots before the cold rolls in.
If you’ve been meaning to divide and transplant your perennials, now may be the best time to do it. Perennials that you dig up, divide, transplant, or re-plant in September have plenty of time to establish themselves in the soil and develop root systems before winter temperatures begin to freeze the ground.
Determine your first fall frost date and aim to take care of this task at least four weeks ahead of time, if not more. For many, September meets this criteria. If you wait too late, your perennials may struggle through winter, even if they’re hardy in your region. The more delicate they are, the more important the timing is.
Perennials that flower throughout summer are sometimes nearing the end of their blooming period, so you probably won’t be missing out on much if you dig them up now. This is especially true for colder climates. Examples include coneflowers, yarrow, and salvia. These plants aren’t putting much energy towards blooming, so it’s a safe time to divide and transplant. In milder regions, wait until winter (after fall flowering) to divide.
As for perennials that bloom in spring, such as peonies and irises, autumn is often the preferred time to divide and transplant. If you want these plants to put on a show in spring, the last thing you want to do is divide them during that time, which would disturb the flowering process.
Instead, wait until September. Give spring-blooming perennials all winter long to establish, and they’re much more likely to bounce back in time for their regularly scheduled blooms.
Collect Seeds
This month is a great time to collect seeds from various plant types.
September is one of the best months to collect seeds from the garden. At this point in the growing season, many natives, annuals, and popular garden vegetables are producing seeds and fruits. Collecting your own seeds saves you money and allows you to develop your own varieties over time. Plus, you can share your seeds with gardening friends, and it’s fun.
Many native plants are producing seeds at this time of year, including iconic pollinator plants like milkweed. You can easily collect native milkweed seeds and spread these important plants around your area, ultimately providing habitat and food for monarch butterflies.
Now is also a great time to collect seeds from some of your annuals. Nasturtiums are excellent companion plants in the garden, and many live in regions that are too cold for nasturtium seeds to survive winter outdoors. Collect them in September to store safely until spring.
Of course, if you’re growing your own tomatoes, peppers, pumpkins, you can collect their seeds, too. After a few summer months of eating peppers from the garden nonstop, you may be accumulating excess fruit. Beyond canning, pickling, and other processing methods, saving seeds can cut down on planting costs and connect you more closely to the full lifecycle of your crops.
Saving tomato seeds for next year may just become your September tradition. This is a simple way to preserve heirloom varieties over the years and even pass down seeds through the generations. Properly dried seeds can remain viable for many years.
Process Your Harvests
It is the ideal season to pickle, can, or preserve your harvested crops.
If you’re anything like me, you’re drowning in garden vegetables in September. Gardeners in many zones have been harvesting the fruits of their labor for months, and you’re about to have an influx of fruits when you harvest everything before the first frost.
September is the perfect time to get started with canning, pickling, drying, and so much more. If you have way too many tomatoes, maybe this year is the year you finally try making and canning your own sauce. You could also prepare salsa.
Speaking of salsa, there are plenty of ways to process peppers. Try making hot sauce, hot jellies, or your own roasted red peppers. You could even dehydrate them to prepare your own spices and crushed red pepper flakes. Jalapenos and banana peppers make excellent pickles, too.
If your cucumbers are still producing, it’s probably time to make the last batches of pickles. Throw a few slices of your jalapenos in a jar or two to spice things up. Have you tried zucchini pickles? If you’re still struggling with the classic dilemma of having way too many zucchini, try pickling them. Thinly sliced zucchini and squash pickle chips are delicious on a sandwich.
There are really countless ways you can prepare all your harvests. You might even just make a giant veggie soup and freeze portions for winter. Some gardeners get tired at this point of the year and are sick of harvesting and preparing; but don’t give up yet! In most zones, this time of year is the final push. Make a giant pot of vegetable stock to add to soups through winter!
Plant Cool-Weather Crops
Some crops prefer the cool fall weather, such as lettuce and spinach.
Depending on where you’re located, the growing season may not be over just yet. There are plenty of cool-weather crops that actually prefer the lower temperatures and shorter days. They may even be frost-tolerant.
September is the perfect time to sow a lot of garden greens such as lettuce and spinach. In fact, spinach is typically grown as a spring or fall crop, though in spring, it’s only a matter of time before your spinach bolts. Spinach can survive below-freezing temps. Plant it now, and you can harvest throughout the winter.
This is also an ideal time to start root crops, such as radishes, carrots, and beets. Radishes are particularly fun because of how fast they grow. Cultivars like ‘Crimson Giant’ take only 28 days to maturity from seed.
In warm climates, you have plenty of options this time of year, especially if you’re in a zone that doesn’t really see frost. Try starting Brussels sprouts now and they should be available to harvest in late winter or early spring.
Lastly, mild- and cool-weather gardeners know the struggle of growing cilantro in the spring. It seems to bolt after a single sunny day, and it’s always going to seed by the time your jalapenos and tomatillos are ready to harvest. Plant cilantro in September and enjoy it until a hard freeze.
Plant Spring-Blooming Bulbs
Plan and prepare what bulbs you want to bloom in the coming spring.
If you love seeing crocuses, daffodils, and tulips bloom in the spring and always think “I should plant those this fall,” now is the time. Depending on the exact bulbs you desire and your hardiness zone, the best time to plant varies throughout the autumn season. For many in colder zones, it’s September.
Perhaps your zone’s ideal planting window for spring-blooming bulbs is October, November, or even later. If so, then you’re going to want to order your bulbs ASAP. Popular and unusual varieties sell out fast. Many online retailers will mail your bulbs when the timing corresponds with your zone’s best planting window.
Prepare a list of bulbs you’d like to see in your garden next spring, research the best planting time in your zone, and plan or purchase accordingly. Consider:
- Hyacinths
- Grape hyacinths
- Irises
- Snowdrops
- Daffodils
More often than not, spring-blooming bulbs prefer full sun conditions, so choose a spot wisely. Plant flowering bulbs when night temperatures are consistently in the 40 to 50°F (4-10°C) range.
In general, you’ll want to plant your bulbs at a depth that is three times the length of the bulb, with the pointed side facing upwards. A bulb planting auger can speed up the whole process.
Once you’re done, don’t forget to water in your freshly planted bulbs. It’ll be a while before the fruits of your labor pay off, but once they start blooming in spring, you’ll be so glad that you put in the effort.
Weed Thoroughly
Focus on weeding when it is easiest.
Okay, it may not be the most fun task, but it’s still super important. September is prime time for weeding, which can make this month more aesthetically-pleasing in the garden as well. Personally, I know it can be tempting to slow down your weeding schedule in fall, but it’s actually crucial that you keep up.
It may seem like winter’s right around the corner, but many zones still have a lot of the growing season remaining. Your flowers and veggies are already getting less sun each day, so they don’t need water and available nutrients stolen from weeds, too.
Plus, you may think winter kills the weeds, but this is simply not true. Your perennial weeds will be slowly establishing themselves all winter long, ready to emerge triumphant in spring—unless you remove them now. Pull them up, root systems and all, before their above-ground foliage withers.
This is also a time when removing weeds is simply easier. Many have just germinated and are smaller, making them a breeze to remove. As the color of your grass or other foliage begins to fade, green weeds will stand out, so you’ll spot them without effort.
When you’re excited to get going in spring, the last thing you want is a bed of weeds to start with. Your future spring self will thank you.
Plant Mums
Fall is the season for lovely and diverse mums.
There’s just something special about planting chrysanthemums in the fall. Whether you’re preparing container arrangements of annual mums for your front door, planting hardy, garden mums right into your beds, or growing specialty heirloom mums—it’s a fall tradition.
Many beginner gardeners don’t realize that there are both annual and perennial mums. The annual mums, also known as florist’s mums, are often found in front of the supermarket and at big box garden centers. These are intended to last for one season.
Perennial mums, also known as hardy mums or garden mums, are perennials that are generally hardy in zones 4 through 9. You can plant them just like any other perennial and expect them to come back year after year in good health.
To make matters even a bit more confusing, “annual mums” are actually perennial in the right zones, typically 7 through 9. If you’re in zone 7 or higher, you can probably keep most mums going well after fall.
So whether you’re the type of gardener that’s just looking for a temporary, autumnal container plant or the type who nourishes a plant for many years, there is a variety of chrysanthemum out there for you. In fact, you can even order heirloom mums of unusual shapes and colors from online catalogs.
Adjust Your Fertilizer
Gradually reduce how much you fertilize your plants as the weather slowly cools down.
As the days get shorter, plants will be putting out less growth. This means they’ll need less water and less fertilizer. September is a good time to start adjusting your fertilizer schedule, offering your plants fewer nutrients than you were at the height of summer.
If you keep applying fertilizer at peak-July numbers, your plants won’t know what to do with it. Any excessive growth you get will just be wasted when winter grows around. Plus, some forms of fertilizer aren’t cheap, so there’s just no reason to spend the money.
However, it’s crucial that you don’t stop fertilizing entirely. It’s important to keep feeding your soil in addition to the plants, maintaining a balanced soil ecology. You don’t want your soil to be devoid of nutrients when spring rolls around.
Continue fertilizing occasionally until a few weeks before the first frost, but perhaps cut the amount you usually use in half or dilute it. Perennials will need some nutrients to develop roots over winter, and you want to encourage a healthy soil microbiome, even in beds that only have annuals.
In addition to applying fertilizer, there are other steps you can take to feed and protect your soil, such as planting cover crops and mulching before winter.
Plant Cover Crops
Cover crops can help protect soil from erosion.
September gardening is also ideal for nourishing the soil. There are so many good reasons to plant cover crops, and it’s not just a practice for large-scale farmers. Whether you have a few gardens around your house or just a single raised bed, cover crops are for you.
The phrase “cover crops” refers to crops that you sow to cover the soil, which has many benefits.
These crops protect your soil from erosion, creating a barrier from wind and rain. They compete with weeds to keep them at bay, so you won’t return to weedy beds in the spring. They also add organic matter to the soil, promoting good soil ecology.
Lots of popular cover crops, particularly legumes, also perform nitrogen fixation, which refers to their ability to convert atmospheric nitrogen into available nitrogen for plants. Some of this nitrogen becomes available in the soil quickly, and even more becomes available when these plants complete their life cycle.
If you have certain beds or areas of your garden where you plant the same things over and over again, like tomatoes, it’s a good idea to plant a cover crop in between. Otherwise, you’re inviting plant pathogens to a well-known tomato hotspot over the years.
There are plenty of cover crops to choose from. Consider planting annual ryegrass, hairy vetch, buckwheat, or crimson clover. Cover crop seeds are often sold in larger quantities to spread over larger areas.
Mulch Before Winter
Mulching can yield many benefits if done right.
Adding mulch in September has plenty of benefits for your soil and your plants—not to mention that it makes beds around your home look neat and tidy. As for the timing, as long as you get it done before the first frost, you should be good. That’s as early as September for some folks.
Mulch insulates the soil, as well as your plants’ roots and all the microorganisms that live below ground. Keeping the soil slightly warmer all winter will make life easier on your plants and these healthy microorganisms. If you’re growing anything perennial that’s just barely on the edge of “hardy” in your zone, definitely mulch around it.
Like planting cover crops, mulch also protects your soil from erosion and helps prevent weed growth throughout the colder months. In spring, your soil should still be in great shape and will hopefully have minimal weeds.
Mulching before winter will also improve your perennials’ resistance to extreme weather while generally protecting your soil.
Move Houseplants Indoors
It is a good time to move houseplants indoors if they suffer in cold temperatures.
Finally, if you have any houseplants that you’ve been keeping outdoors for a spring and summer boost, now may be the time to bring them inside. You may be able to return them to their prior indoor spots, but if you’ve been collecting even more houseplants all summer, you may have some rearranging to do.
The exact temperature requirements will of course vary from plant to plant, but most tropical and subtropical plants will not appreciate night temperatures that dip below 50°F (10°C). A few nights that just barely get below 50 won’t be a death sentence, but once this milestone is reached, bring your houseplants back in to enjoy room temperature.
Of course, always bring your houseplants in before the first frost. Realistically, they should be inside long before this time.
While it would be difficult to give your recently-outdoor houseplants equally good conditions as the great outdoors now that they’re inside, do your best. This is a good time to research grow lights, consider which plants get priority locations, and consider moving furniture around to make window space.
But don’t stress too much, even if you don’t have perfect indoor lighting. Houseplants that get a few good months of outside sunlight in spring and summer will really thrive, even if they must survive sub-par indoor conditions in fall and winter.
