Dahlia plants are known to attract insects such as ants, termites, beetles, flies and other insectivorous animals. These insects like to eat the plant’s sap and they often cause damage to your plants. If you have a few dahlias growing in your garden or if you grow them indoors, then these pests will most likely affect your crop too. You may want to consider using natural pesticides against these pests. Some of these natural pesticides include:
1) Vinegar – Vinegar kills many types of insects including aphids, mealybugs, scale and spider mites.
The vinegar used to kill the insects also helps reduce their numbers. However, it does not work well on all types of pests. Also, you need to use a strong enough concentration so that the vinegar doesn’t burn your skin when applying it directly onto your plants.
2) Salt – Salt kills many types of insects including aphids, mealybugs, scale and spider mites.
The salt works best on some types of pests but not others. Also, you need to apply the salt directly onto your plants.
3) Vinegar Water – A mixture of one part vinegar with four parts water kills many types of insects including aphids, mealybugs, scale and spider mites.
It also reduces their numbers. The mixture does not work as well as other treatments such as insecticidal soaps or horticultural oils however it is safer for the environment and less toxic to humans.
4) Horticultural Oils – Various horticultural oils (such as canola, vegetable, soybean, or speciality oil) kill many types of insects including aphids, mealy bugs, scale and spider mites.
The oil works best on some types of pests but not others. Also, you need to apply the oil directly onto your plants.
Weed the dahlia bed before planting. Dahlias are deep-rooted plants and do not appreciate having their roots disturbed, so it’s best to weed the bed thoroughly before planting. You can also add a layer of organic mulch once the plants are growing to prevent weeds from growing through.
Plant dahlias after the last frost. It is important to plant dahlias after the last frost in your area because the plants are susceptible to frost damage. It’s best to wait until after the last frost in the spring before planting.
Feed with a slow-release fertilizer. Feed your dahlia plants every six weeks with a slow-release fertilizer that has a high middle number (e.g.
Follow the instructions on the packaging for the correct amount and application.
Dig a hole twice the width and depth of the dahlia tuber before planting. The dahlia tubers should be planted just beneath the surface of the soil and lightly covered with soil. Try not to let the new shoots of the dahlia tuber brush against the soil, as this will cause them to rot.
Plant in groups for a spectacular display. Once the dahlia tubers have grown into plants, you can then start to think about moving them into their final positions in your garden. Space the varieties at least 60cm (2ft) apart so that they have enough room to grow, and plant them in groups to provide a spectacular display.
Add a high nitrogen fertilizer in late summer. Dahlias require lots of nutrients to keep them flowering prolifically all season. Feed with a high nitrogen fertilizer in late summer to promote a good flush of blooms in the autumn.
Deadhead your dahlias once the blooms start to fade to prevent them from seeding and encourage them to produce more flowers later in the year. Deadheading is easy, simply cut the stem of the dahlia off at the base once the flowers have started to brown and die.
Transplant your dahlias after the last frost in spring. Dig a hole at least twice the width of the root ball and deep enough so that only the top section of the tuber is exposed. Replace the soil and water the plant well.
Sources & references used in this article:
Growing dahlias by J Romer – 2003 – mastergardener.osu.edu
GROWING DAHLIAS by COF DAHLIAS – naldc.nal.usda.gov
Spra Ying and Dusting Experiments for the Control of Leafhoppers Infesting Dahlias and Asters by CC Hamilton – Journal of Economic Entomology, 1932 – academic.oup.com
Growing dahlias (Revised 1975) by PE Read – 1975 – conservancy.umn.edu
G74-189 Growing Dahlias by D Steinegger, JE Watkins… – … from University of …, 1974 – digitalcommons.unl.edu
The distribution and nucleotide sequences of chrysanthemum stunt viroid in dahlia fields in Japan and the effect of its infection on the growth of dahlias by S Asano, K Yoshida, T Naka, Y Hirayama… – … Journal of Plant …, 2020 – Springer
Tobacco streak virus in dahlias by T Collins – 2003 – Crowood Press (UK)
Dahlia mosaic virus: molecular detection and distribution in dahlia in the United States by AA Brunt – Plant Pathology, 1968 – Wiley Online Library
Dahlia diseases by HR Pappu, SD Wyatt, KL Druffel – HortScience, 2005 – journals.ashs.org