How to Grow Great Dahlias

Dahlias are such incredible, striking flowers that are so fun to grow. We dedicate a field just for our dahlias, growing around 2,000 in 75 different varieties (those numbers grow each year!). Follow the tips below to grow dahlias just like we do here at Petals in Bloom and you’ll be rewarded with your own abundant, beautiful blooms!

Where to Plant Dahlias like a lot of sun so in order to have yours thrive and bloom abundantly, plant them in full sun (at least 8 hrs.). A spot that isn’t too windy is preferred as well. 

When to Plant They don’t like the cold so be careful not to plant them out too early. Wait until after all danger of frost is passed (for us here in zone 4b, that’s about May 14th). 

How to Plant We put a couple inches of compost on the top of the beds in the fall. Then in the spring, we dig the holes 6-8” deep, 12” apart. We throw a handful of bonemeal in each hole, and an organic fertilizer, mix into the soil at the bottom of the hole, then lay the tuber on its side with the “eye” (new growth) facing up and cover with dirt. DON’T WATER until you see green growth peeking up in about 8 weeks. Watering before you see green growth, dramatically increases your chances of causing your tuber to rot instead of grow. 

How Much Water Once peeking up through the soil, you can start to water regularly (2-4 times a week, deeply). 

Pinching You’ll want to pinch back 1/3 of the plant from the cnter sprout/bud when it gets about 8-12” high. This will encourage more side shoots (= more blooms).

Support Once they get 1-2ft tall, you’ll want to set up support (before they get too big and fall over or grow crooked). This can be a tomato cage if in a home garden, or if growing a larger amount, we use a corral method by pounding in stakes along the sides and then using string/twine all around the edges to make a corral around the entire flower bed.

Fertilizer Apply compost tea to the plant’s leaves and soil every other week.

When to Harvest Flowers are ready for cutting when almost fully opened. Unlike other types of flowers, their blooms won’t really open up much more in a vase then the stage they were cut at. Early morning or evening are ideal times to cut flowers when the temperature outside is cooler. If you check your beds every 3 days for any ready flowers in that ideal fully opened stage, and harvest them, you won’t have flowers overly ripe or have a need to dead head.

How to Harvest Bring a bucket filled with water with you so you can put any flowers you cut directly in cool water. (The bucket should be VERY clean as you won’t want any bacteria getting in the stems and shortening their vase life). You’ll also want clean, sharp scissors or pruning shears. Cut deeply into the plant to get a long stem (this promotes more blooms on long stems), just above a set of leaves. Strip the lower leaves off (this helps the plant not spend any energy hydrating those lower leaves but focusing on extending the life of the flower itself). Then place it directly into your bucket of water. If harvesting during the day, keep your bucket in the shade while cutting if at all possible.

Care of Your Cut Dahlias You can get about 5-7 days of vase life out of a dahlia bouquet. To get the most out of them, change the water in your vase daily. Also, keep the arrangement away from sunny windows, hot stoves, or ripening fruit. To really extend your bouquet, place it in a cooler spot temporarily at night.