In September, summer gardens quickly came to a close for those gardeners who seized the opportunity and planted those fast-growing vegetables and herbs. The weather is downright unpredictable as we move into this month.

Not only are temperatures dipping, but the hours of sunlight are diminishing, and the first frost date is imminent in Zones 1-3. It can feel like you are bouncing back and forth between seasons in some areas, but it only takes one hard frost without cold protection to end the summer garden season.

Find out what to do in your September Garden to make the most out of your growing season and to prep and maintain the gardens as we wave goodbye to summer.

September Garden Planning in Zones 1-3

One thing that remains consistent from zone to zone is planning. While your growing seasons and climates might not be the same, all gardeners in all zones should make planning a big part of their monthly routine. Here are some things to think about throughout September.

• The cooler days of September are a great reminder to prep for frosts and colder weather. Think about season-extending tools like hoop-houses, cold frames, and greenhouses. You can also stock up on row covers to protect crops from upcoming frosts.
• Walk around your September garden with your garden journal and make a note of high-performing and underwhelming plant varieties. If you had some favorite star performers, add them to your list to buy seeds or plants for next year.
• Plan to harvest your own seeds from your garden early this month before the first frost. This is an exciting and rewarding task, and you’ll be grateful that you did when it comes to next year’s garden.
• Make some notes in your garden journal about the weather and how it impacted your garden this year. Were there any significant storms, droughts, or heavy rains?
• Jot down what pests were a problem for you this year and when they popped up.
• Identify which spring flower bulbs you’d like to plant this fall and purchase them from garden centers this month when the bulb selection is most plentiful. You’ll want to get them planted before the ground freezes.
• Recently, there has been a rise in self-sustainability, and some seeds have been hard to come by. Think about what seeds you’d like to acquire for spring and make your purchases now.
• Sketch and/or photograph your vegetable garden layouts and keep them in your garden journal. This way, you will know how to rotate your crops for next year.
• Make a note of any diseased or spotty plants and remove them from your garden. Include the variety of plants and where it was planted, and discard the debris far away from your garden or compost pile.
• If you are planting a garden cover crop this fall, acquire the seeds and get started this month.
• Assess your yard and garden for anything that needs repair or change. Would you like to start a compost area? Does a fence need repair?  Does your vegetable garden need more secure fencing? Would you like to build raised beds or build some climbing structures? Write down any materials that you might need for these projects.
• Check back to your gardening wish list in your garden journal for any items that may be on clearance racks at the end of the summer season. Now is a great time to pick them up at a discount.
• Consider what new perennials and shrubs you’d like to add to your landscape. Early fall is an excellent time for planting.
• Are your seed packets in a jumbled mess after this summer of vigorous planting? Consider ordering some seed organizing supplies and write this down as a late fall or winter task.

Fall Garden Prep & Maintenance

Late Summer Garden Weeding

Keep up with organic weed control as you see them throughout the month of September. If weeds have gotten out of hand, you may be tempted to let them be and have future frosts kill them off.  Avoid this methodology because you don’t want those weeds to go to seed and be even more of a problem next year.

Mulching The Fall Garden

Mulching remains a high priority on the September garden checklist Zones 1-3 because it is so beneficial to gardens. Continue to mulch your garden beds in the fall. Here’s why:

• It gives the September garden a fresh look.
• Mulch enriches the soil over time as it breaks down.
• Mulch stomps out those fall weeds.
• Prevents soil erosion from heavy rains, winds, and storms.
• Retains moisture during bouts of drier weather.
• Insulates bulbs perennial root systems for the upcoming cold weather.

When & What to Fertilize in Zones 1-3

• Stop fertilizing trees and shrubs if you haven’t done so already. Cooler weather is approaching, and new growth established from fertilization can cause those limbs to be susceptible to damage.
• Fertilize protected vegetable gardens as needed.
• Add a cover crop or organic fertilizer to vacant gardens that have finished producing. Organic fertilizers help build the soil and take time to break down to be available to plants for the next growing season.
• Fertilize plants growing in greenhouses and hoop houses.

September Garden Pruning

• Stop pruning trees and shrubs. Cooler weather and frosts can cause new growth to be susceptible to damage.
• Continue to deadhead annuals and perennials.
• Allow perennial plants to die back before cutting them back. Allow some seed heads to remain on plants for birds to feed on and for seed collection.

Other September Garden Tasks for Zones 1-3

• Early September is a great time to divide perennials like hostas, daylilies, rudbeckia, Shasta daisies, etc. Avoid dividing if harsh weather has already rolled in.
• Plant new hardy perennial plants in the cooler days of September but before the first frost. This gives plenty of time for roots to get established before winter sets in.
• Early in the month, dig up tender tubers of gladiolus, dahlias, cannas, and caladiums and store them in a dry peat moss over the winter.
• Bring in any houseplants that you’ve had outside this summer.
• Tidy up your garden landscape, picking up any dried foliage, dropped fruit, or dropped leaves.
• Collect seeds from high-performing plants and store them in seed collection envelopes. Don’t forget to label them.
• Plant your spring bulbs early in September.
• Turn your compost pile with a pitchfork. Remember not to place any diseased foliage into your compost heap.

Indoor Planting in Zones 1-3

This month you can start some high-producing plants indoors and grow them in pots under grow lights. Planting high-yielding plants like tomatoes, peppers, cucumbers, and herbs indoors with grow lights can allow you to produce high-quality vegetables that would otherwise not thrive in Zone 1-3 climates.

Outdoor Planting in September

Plant a fall crop of fast-growing vegetables like radishes, lettuce, summer broccoli, and kale in greenhouses. Protect any existing plants by covering them with a cold frame or move them to a greenhouse to get the most production out of the already producing plants.

Depending on the weather conditions, you may or may not have success. Jot down achievements and disappointments in your garden journal and make adjustments for next year’s September garden.

Late Summer Garden Harvesting

Harvest everything that you can in early September before frost hits. If plants are still producing, give them a fighting chance by providing protection with cold frames or hoop houses or bring potted herbs and vegetables indoors or into a greenhouse.

If you’d rather harvest your herbs instead of growing them indoors over the winter, harvest and dry them entirely at this time.

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