Category Archives: Growing Dahlias

Planting tips for your new Dahlia season

  1. Water plants two days before planting.
  2. Plan and place stakes before planting.
  3. Common spacing is 24 inches between plants (30 inches for larger plants, 20 to 24  inches for smaller plants)
  4. 60 inch stakes with 12 inches in the ground is good support.
  5. Dig hole twice the size of pot and sprinkle in a small amount of slow release fertilizer. (14-14-14 or 10-10-10)
  6. Place dahlia in hole, tamp in and tie to stake immediately. (leave some slack in loop to allow for growth or it will cut into stem as the plant grows)
  7. Water thoroughly and leave for two weeks unless extremely hot — this forces strong, deep root development.

Control of Cutworms — Submitted by Reg & Marlene Powys-Lybbe

 Fear of moths (mottephobia) runs in our family both my mother and my aunts were deathly afraid of the menacing- miller.  As a young boy I scored points for tracking down moths and killing them when they ventured inside.

How does this relate to cutworms?  Cutworms are the larvae of miller moths.

The Pale Western Cutworm is the cutworm most common in Alberta.

 An excellent resource on insect – pests and their control is “Insect Pests of the Prairies” published by the University of Alberta. The information that follows is based on material in that text and personal experience as related to glads and dahlias in particular.

Preventative measures-

1.  Delaying cultivation of the ground in August and September

The adult female prefers to lay her eggs in loose soil. If the crust which normally forms over the soil in summer is left in place the females are more likely to seek a more suitable site to lay her eggs.

2. Watering -The eggs of the moth do not hatch until spring (March to May) depending of soil temperature.

Once the eggs hatch into larvae (April to June) if there is a period of 12 consecutive days of 6 mm of precipitation in a row cutworm populations are drastically depleted. Gardeners could insure that such an event as this occurs.

Mechanical Control-

When cut worm damage is observed, you can usually locate the cutworm alongside the shoot (stem) that is damaged. Simply, dig with your finger around the stalk and you will often locate cutworm – which you can dispose of. This is best done in the morning. Note- cutworms are rather well camouflaged and you usually have some difficulty seeing them. That they are generally moving once dug up helps.

Occasionally, with glads the cutworm will be right in the stem just above the bulb and squeezing the stem will kill it. Usually however the cutworm will stay close to stem its food source rather than in it.

Note – if the stem or stalk is not cut off it will survive the damage. With dahlias in particular, the stem is likely to be completely cut through – New shoots will develop but the blooming date will be delayed.

Trying to find the cutworm is important as it spends a rather long time in the soil and will move on to new plants or the new shoots as they develop.

Chemical Control –

1.       Dusting glad bulbs with bulb dust at the time of planting is effective in controlling cutworms on glad bulbs and would probably work for dahlia tubers too.

2.       Spraying with a systemic  insecticide  will help control the cutworms

3.       Contact chemicals will work as well –both sprays and dusts.  Although the cutworm spends most of the time underground; when feeding it comes to the surface cuts off what it wants and pulls it beneath the surface to continue its consumption. If the infestation is not wide spread, you may wish to target the particular plants showing damage or a particular area where the cutworms seem more active rather than generally spraying or dusting everything. As the cutworm feeds through the night and early morning it is generally most effective to spray (dust) in the evening.

Control of adults-

Once the larvae pupate – further control is probably not practical until the adult moth emerges. Natural- predators of the moth such as bats and birds are your best bet at control the adult stage. Bat boxes can be purchased which provide shelter for the bats.

But, if you have family members afraid of millers, knowing that you are rearing bats in your yard is unlikely to encourage visitors.

One of our cats used to love moth hunts when she was alive. I would take her outside and hold her close to where the moths were flying by the door light. She would catch the moths against the wall and proceed to eat them. Our vet assured us that they were a good source of protein though they were too crunchy for my taste

Dahlia planting tips


Water plants two days before planting.

Plan and place stakes before planting ( common spacing is 30 inches between larger  plants and 20 to 24 inches for smaller plants).

60 inch stakes with 12 inches in the ground is good support.

Dig hole twice the size of pot and sprinkle in a small amount of slow release fertilizer (14-14-14 or 10-10-10)

Place plant in hole, tamp in and tie up immediately. (leave slack in loop or it will grow into stem as plant develops)

Water thoroughly and leave for two weeks, unless extremely hot.  ( This allows for strong deep root development)



These planting tips have worked with some of our members in the past, if you have other methods you have found successful please feel to leave a comment. You can do this by clicking the “leave a comment” below. Your knowledge will help us grow better dahlias.


  • Bring tubers fifteen days… three weeks out of cold storage to stimulate and break dormancy.
  • Transfer to an area of normal house temperatures.
  • Check tubers for any root or softness.
  • If tubers are in a clump form, wait for the eyes to show and then divide tubers off of the clump.
  • When the eyes are evident, pick out the stronger eyes tubers and prepare to pot them.
  • Using 6”‐8” pots, fill them ¾ full with planting soil or peat moss.
  • Plant the tuber in a horizontal position, with the eye ½” below the surface of the soil.
  • In two weeks, green foliage should begin to appear.
  • By June 1st you should be able to transplant them outside to your garden.
  • Each plant should have three sets of leaves and be 6”‐8”. Keep in mind, DAHILAS CANNOT STAND ANY FROST. Before doing this, make sure to check the weather forecast.

Started Dahlia Tubers


In central Alberta, we plant our tubers directly into the ground between the 15th of May and the 1stof June.

Weather varies each year, so we cannot stress enough to check the weather report.


  • The soil should be rototilled or dug to a depth of 8”‐10”.
  • A 10‐10‐10 or 14‐14‐14 slow release fertilizer can be dug in at the same time.
  • Stakes should be put in the ground with each plant.
  • The stakes should be 3’ high and spaced approximately 20” apart.

Eight Week Old Dahlias


  • Place the plants next to the stake and tie the plant to it. You should use a non‐abrasive material, such: light string, cotton, nylon, pantyhose, etc.
  • Place the tuber with the eye next to the stake, the tuber should be horizontal with the eye covered with ½” of soil.



 It is time to pull your tubers out of storage and give them a thorough check. Look for any rot, if the tuber is 3/4 rotten discard. If it is 1/2 rotten you can cut the bad part off as this will sometimes save your tuber. Check for broken necks on your tubers, and if they are weak or broken discard. Also check the top of the tuber for stem rot. This will show up as black rot above the eye of the tuber. You can trim this up and a good idea is to spray this area with lysol. With this all done check your medium that you have your tubers stored in and make sure it is dry. If it is moist put in fresh dry medium. With this all done put your tubers back into storage and check them again Feb 1.  Good Luck