My first few years growing dahlias were ultimately unsuccessful. I grew healthy plants, but they would never bloom. It wasn’t until I met a 2nd generation flower farmer, John La Salle, that my dahlias started flourishing. Much of the dahlia-related knowledge he shared with me is outlined below.
When living in New England, especially in colder areas, plants have to go in the ground as early as possible. As soon as the soil is thawed and workable we plant our dahlias – usually between the last week of April and first week of May. My goal is to be done planting dahlias by May 15th. They take three months to start producing blooms, so that means blooms are in the field from August until the first frost. First frost tends to occur anywhere between the last week of September through mid-October. Because of the short season, I plant in a high tunnel so we can have blooms from mid-July through November. The tubers are safe in the ground as long as the ground does not freeze – a little frost on the leaves is what I like to call nature’s pinching. It doesn’t hurt the dahlias.
Soil structure is critical. If you have clay soil, dahlias may not be the crop for you. They love water, but it has to drain. Clay is too dense and it’s small pores will retain water instead of draining it, and the result is a rotten tuber. However, you can plant in containers or build large wooden raised beds which should be at least 3 feet tall filled with a sandy loam and amended with compost.
Everyone loves dahlias, right? That includes earwigs, leafhoppers, tarnished plant bugs, Japanese beetles, corn borers – the list likely goes on, but those are my main pests. All these can cause viruses and deformation, so I use bio-insecticides (real pyrethrum & neem oil) and malathon-based insecticides (can be bought in a hardware store). I do not recommend regularly using toxic chemicals like malathon, but I use them as needed and only to knock down large insect populations. Keeping the area weed-free is critical for minimizing pests and maximizing successful growth. I use straw mulch (not hay) to hinder weed growth, and our free range laying hens help with pest control and weeding as well (bugs are tasty snacks to them!).
Dahlias grow from a tuber that looks somewhat similar to a potato (potatoes are actually a type of tuber). Healthy productive tubers are a must. Because John was so successful, I bought 100 tubers from him, all of which were prolific and produced excellent cut flowers. Every year I trial new verities and change what I grow to meet market needs.
Dahlias are a major crop for The Painted Tulip. It has taken me 10 years to get to this point, and now I grow and sell the blooms and tubers. This crop is a labor of love that not every farmer or gardener has the time for.
Whether you are a flower farmer or a gardener we have a tuber store to get you started on building your dahlia collection. All of our varieties are used for cut flower production.
Please feel free to ask questions or add your dahlia growing tips in the comments.
Here are my planting recommendations:
Dahlias love sun. Place the root on its side about 6” -9” deep in loose soil that is well drained. If you have gravelly/very sandy soil you might want to mix in some compost. Allow for 12”-20” spacing between plants. Use 5-10-10 fertilizer a few times after the plant is a foot tall. Water once weekly. Remove deadhead flowers to encourage blooming. Blooms from August until frost. Bulbs need to be dug up for the winter. Store them in a dry, dark 40-45°F location. DO NOT LET THE TUBERS FREEZE.
See my blog post on storing dahlias – yet another challenge to cultivating them.
Thank you for reading our blog and Happy Spring!
Wild Orchid says
Thank you for sharing such a beginner guide. worth reading the details.
Jenny Fritz says
This is a great read. I live in NH and usually put my dahlias in May 15th After reading this I’ll try for May 1st. I had a really early bloom last year (late July). Thanks for sharing your knowledge.