Simon from the Walking Talking Gardeners YouTube channel has identified 10 vital gardening jobs that should be completed before September ends, covering everything from planting spring bulbs to repairing lawns and taking cuttings. With only two days left in the month, he says September is the "last best month" in the growing season.
Tomato care and spring bulbs
First on Simon's list is preventative maintenance for tomatoes. "The nights are getting colder," he observes. "It's beginning to get really quite damp. And this is where the late summer blight starts to rear its ugly head." He advises monitoring tomato plants closely, removing any flowers or very small fruits that won't develop properly, and harvesting tomatoes as soon as they ripen: "You don't want them falling on the floor."
Simon emphasises that gardeners need to be "on it" with their tomatoes because if late blight strikes, "that is your entire crop gone in a couple of days."
For spring bulbs, Simon notes that while tulips can wait until January, alliums and daffodils need to be in the ground before the end of this week. He points out that bulbs in garden centres are currently "at their freshest, at their biggest, and at their best," but will deteriorate if they hang around in shops for a couple of months, losing moisture and condition. The likelihood of fungal infections, especially with daffodils and tulips, can also rise over time.
Perennials and lawn repair
Simon recommends examining hostas, heucheras and geraniums for opportunities to divide them and create new plants. "Lift them now," he advises. "Try to disturb the root system as little as possible. You don't want to be mocking about breaking all the roots when you're trying to get it to re-root. If you just damaged it, you've just slowed down that process." He also suggests taking off old leaves to prevent herbaceous plants from drying out.
For lawns damaged by summer heatwaves, Simon says the initial task is to scarify, weed and feed. He advises that now is the final chance to apply all-in-one granular lawn feed, weed and moss killer: "Come the end of September. We don't use those any more." He explains that once the weather cools in October and November, it's too late because the grass and weeds need to be actively growing for the chemicals to take effect.
Dead-heading and basket refresh
Simon highlights dead-heading as particularly effective for dahlias and roses. "When you have a spent bloom, the seeds inside are being formed," he says. By dead-heading, gardeners encourage plants to produce additional flowers. "If you don't dead head these, then it triggers the plant to stop flowering, stop putting energy into these node buds and flowering will come to an end."
For hanging baskets that look weary, Simon suggests refreshing the entire planting with "hardier, more autumn-coloured plants" such as cyclamens, pansies and heucheras. He notes that new seasonal bedding has "a good six weeks where it can grow, establish, and look good for the winter period."
Feeding, cuttings and greenhouse
Simon explains there is minimal benefit to feeding plants beyond late September, as it encourages lush growth that could be damaged by frost or attract biting insects. If feeding is necessary, he advises switching to low-nitrogen feed such as Tomorite or Maxicrop seaweed-based fertiliser. "Typically for most garden plants September is the last month for feeding," he says.
September is also the last opportunity to take cuttings of frost-susceptible plants like geraniums, pelargoniums, coleus, fuchsia and salvia. Simon warns: "This is your last time to take cuttings of those."
For vulnerable plants like citrus, Simon advises considering overwintering options. "An unheated greenhouse will be fine. They will be alright outside for now, at least here in the mildest parts of the UK," he says, but notes that colder regions may already be experiencing frost.
Finally, Simon recommends tidying the greenhouse now, removing dead plants, scrubbing surfaces and cleaning windows. "Do this job now. Don't wait until the winter. Don't wait until the spring because you'll have far too much work to do," he advises.
