Mosquitoes: The plant shown above, is a scented geranium, known as Citrosa, commonly known as mosquito plant. One plant makes a lovely shrub in a 15" pot. Two plants make a more magnificent, effective show. I make 2 pots of 2 plants each. One goes near our seating area on the deck, the other one beside the door, just close enough that the door brushes the leaves, and even sometimes pinches the leaves on opening and closing. This also reduces the number of flies that come into the house.
Just the presence of the plant does not repel mosquitoes--it needs to be rubbed a bit to release the scent. You can also rub the leaves and then rub the hands on exposed skin.
Gophers, moles and voles:
Castor bean plants (Ricinus) planted at the corners of the garden keep these burrowing varmints away. I used to have a problem with voles. Then I planted the castor beans about every20 feet on the long side of the garden. No voles that year. Next year, I forgot--still no voles. The next year they were back, but I still had castor bean plants--planted them, and the intruders left. Some of our customers say they drop castor bean seeds into the gopher holes with the same effect.
Aphids in Dill :
A lady came to our greenhouse today and bought a lot of our "Lemon Gem" Marigolds (also known as "Tagetes". They are strongly scented. She plants them near any plant that is aphid prone, such as Dill, and has no aphids--she travelled 50 miles to our place just for these plants.
Cabbage worms and other pests:
It is said that African marigolds (large-flowered ) keep many pests away from the garden. I believe this is a myth. Marigolds do repel root nematodes, but cabbage butterflies like my garden even with an ocean of marigolds (I plant tons of Crackerjack marigolds everywhere because I like the look of marigolds throughout my garden, and .......just in case).
For cabbage worms I dust with Rotenone powder--I bought an old-fashioned powdering pump so the dust would go farther and I can dust the undersides of the cabbages as well.
I rarely (Only twice in 26 years in this garden) get Colorado Potato Beetles. I hand-pick the beetles and the salmon-colored larvae.
I wish you all a pest-free summer.