Dahlia Growing Guide

Dahlia tubers like well-drained medium ph soil that has at least half a day of sun, full sun is best.  Peat moss and organic matter with some bone meal are good soil additives – work in well 2 weeks or more before planting.  Try not to use too “hot” of organic matter.  A good commercial fertilizer with equal parts nitrogen, phosphorus and potassium, such as a 16-16-16 works well at planting time.  Work it well into the soil so as not to burn the tuber sprouts.

April and May are ideal times to plant new tubers as long as the ground is not too wet or cold.  Make sure there is not any threat of frost.  Dahlias will rot if the ground is too wet or cold.

It is better to wait until the weather has warmed than to plant them too early!

Be careful not to plant dahlia tubers too deep.  The best way to plant dahlia tubers is to dig a hold about 3 inches deep.  Put the tubers on their side with the sprouts pointing upward.  Cover with only 1-2 inches of soil to start. Then gradually mound the soil as the dahlias sprout to give them a good strong stalk.  A stake can be put in at planting time to support taller dahlias.  Water tubers at planting time if the ground is dry, but if ground is damp, they will have enough moisture to get them started.  Do not water the dahlias (outside of normal rain) until the first shoots come up from the ground.  Young tubers do not like to be in overly wet soil or will rot.

Bug Protection – use a good slug bait.  Follow label directions carefully as the sprouts start to come from the ground.  Slugs do a lot of damage, but earwigs and sow bugs also eat new sprouts so use a good insecticide to get rid of them.

Fertilize a second time when plants are 12 to 18 inches high with a commercial or organic fertilizer that is low in nitrogen, but high in phosphorus and potassium to promote blooms, such as a 5-10-10.  Fertilize again when the plants are starting to bloom well.  It is preferred to not fertilize after the beginning of September or so as the roots could get soft.  

Pinching – If you pinch the center of the sprouts out when the plants have 4 to 6 leaves, this will allow more sprouts and gives a much bushier plant, which will promote more blooms.  Water the dahlias thoroughly and deeply every week, 2 or 3 times a week if temperatures are really hot and no rain has fallen.  Check the soil to see how dry it is as tubers are down 6 inches.  

Cut flowers in the cool of the day.  Bring indoors and place stems in 2” of hot water (160 F).  Leave in the hot water until it cools or until the stems turn darker at the ends.  Flowers can be cut again and arranged as desired.  The hot water gives them a longer life and can liven up wilted blooms.  A flower food added and a couple of drops of bleach added to the water of fresh flowers helps as well.  

There are a lot of internet guides for bugs, pests, digging and dividing tubers and storage to research.

Good luck and wishing you years of beautiful blooms!

Your friends,

Paisley’s Petals