I interviewed Neil Miller, head gardener at Hever Castle Gardens, on how to grow roses. He told me that he never sprays his roses to deter aphids, because he too runs a wildlife-friendly professional garden. In June, the roses are covered with aphids. But he leaves them. And two or three weeks later the aphids are gone ‘and the thrushes are waddling around with big bellies,’ he says.
For two years running, I’ve tried this on my dahlias. On 6th July, the stalks of several dahlias were thick with aphids. I did nothing to control them. By the beginning of August, they were all gone. They were eaten by the birds and (perhaps) some earwigs.
If you have been using pest killers for a while, it may take time for your predator population to build up. So if you try leaving your aphids, and the birds don’t sort them out, check how wildlife friendly your garden is.
As Steve says, you need to invite wildlife into your garden if you want them to control your pests without chemicals. That means offering water as well as plants that offer food or shelter. And check that any products you use to kill off pests are organically approved. And minimise their use in the garden. There’s more about creating a wildlife-friendly garden here.
And if you’re wondering whether to dig up your dahlias at the end of summer, this post may help.
What if my dahlia isn’t flowering?
Steve says that if your dahlia isn’t flowering, the most likely reason is that it hasn’t had enough water. ‘The singles and the collerettes, with smaller flowers, are more drought-resistant’, he says. But the larger, ‘dinnerplate’ dahlias need much more water than most in order to flower properly.
If your dahlia has buds, but they just wither away without turning into flowers, he says that is most likely due to lack of water.
Although you don’t always have to fertilise dahlias, the bigger flowers do need more nutrition than the smaller or single-flowered ones. Steve uses Maxicrop Seaweed feed on his dahlias.
And, of course, if you’re growing dahlias in pots, you will either need a long term slow release feed or to feed the dahlias weekly in the flowering season.
The products I use to control pests without chemicals
I’ve tried a number of brands of sheep’s wool pellets and organically approved slug pellets. The ones I’ve continued to buy and use are Vitax Slug Gone Natural Wool Pellets , Richard Jackson’s Slug and Snail control and Neudorff Slug and Snail killer. Both of the last two contain ferric phosphate as their active ingredient.
And I keep a pair of Darlac Snips beside the back door, so that I can dead head flowers regularly when I go out into the garden.
Pin to remember dahlia pest control without chemicals
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