|How to Take Cuttings
by Ted & Margaret Kennedy
How to Take Dahlia Cuttings
by Ted & Margaret Kennedy
Introduction: There are probably as many ways to propagate dahlia cuttings, as there are dahlia growers. We have been taking
cuttings for many years now and wish to share some of our methods with you.
Why not just grow dahlias from tubers? Why go to the bother of taking cuttings?
Advantages to cuttings:
(1) Economy: One tuber can produce 3, 4 or as many as 5 to 10 plants from cuttings. That means that from one tuber you can get
enough plants for yourself and some to share with your neighbors. Some new dahlia varieties sell for as much as $25.00 and taking
cuttings is a way of growing several plants of those expensive dahlias. As dahlia breeders, we use cuttings to increase our stock so
that we can evaluate potential new varieties and then have enough tubers to enter into trial gardens and finally to have enough tubers
(2) Early flowers: Cuttings taken in March and April can be planted outside at the same date you plant tubers, which is about May 15th
here. The plants grown from cuttings will flower weeks ahead of your dahlias grown from tubers.
(3) Disease detection: Cuttings that show signs of virus or other disease can easily be discarded. A tuber will have been in the ground
for as much as a month before you can see the leaves. By that time it may be too late to replant with another tuber (if you have one).
(1) Dahlias grown from cuttings will produce tubers clumps that may be difficult to divide. I figure on getting about three tubers from a
plant grown from a cutting. I figure about five tubers from a plant grown from a tuber.
(3) Time and equipment: You need some lights and shelves and perhaps a green house or cold frame, and lots of pots and flats. It
does take time to tend to your plants.
We do not use any rooting hormones to produce our cuttings. Dahlias root very easily without them and why expose yourself to
Outline of the Cutting Process
(1) Tubers or pot tubers that will be used for cutting stock, need to be potted in a soil medium in sterile 4-inch pots or laid horizontally
(2) The watered pots or flats are placed on a shelf or bench about 6 inches from a florescent light source.
(3) The temperature under the lights should be room temperature , about 68 to 72 degrees.
(4) In about 2 to 3 weeks the tubers will have 2 to 3 inch shoots.
(5) Cuttings are taken from the tubers.
(6) Cuttings are inserted into 2.5" pots filled with sterile germination soil mix.
(7) The pots are lightly watered and placed into a sterile flat.
(8) The flat, full of cuttings, is inserted into a 13 gallon kitchen bag and tied shut.
(9) The flat is placed on the shelf or bench 4 to 6 inches under the florescent lights.
(10) After 11 days, open the bag and check the pots for roots.
(11) Remove the plastic bag from the cuttings and leave the flat under the lights for 3 to 7 days.
(12) Water cuttings as necessary; do not fertilize yet.
(13) Move cuttings to the green house or cold flat or lighted window.
(14) When the cuttings are about 20 days old, water with 20-20-20 greenhouse fertilizer diluted to one-third strength.
(15) Optional: After two weeks or so, replant into four inch pots using a good soil mix.
(16) Plant in garden and bury plants deeper than they were in the pots.
(17) Protect the plants from damage by slugs, as they are cuttings worst enemy.
(18) Grow as you would a dahlia grown from a tuber.
(19) Enjoy the wonderful flowers, weeks earlier than plants grown from tubers.
Materials and Equipment List
Pots and flats: Lots of 2.5 inch pots and flats to match. A box of about 1000 2.5 " pots costs about $40.00. We use 10 x 20 flats that
hold 36 of the 2.5 inch pots.
Shelf Unit: A plastic shelf unit that is about 6 feet tall, 40 inches wide and about 16 inches deep, with five shelves. Cost is about
$40.00 at Home Depot.
Florescent Light Fixtures: The cheapest 4-foot shop lights that sell for as little as $10.00 are just fine and are sold at Home Depot and
I saw them recently at Bi-Mart.
Electric Strip to plug in Lights: A cheap grounded strip with 5 plug in slots is fine. Nice to have a switch to turn all of the lights at once.
Florescent Tubes: Cheap florescent tubes work fine although for a little bit more you can buy tubes with more lumens. The cheapest
ones work just as well as the expensive ones. We use 40-watt tubes. "Grow Lights" produce a more balanced light but for our
purposes are a waste of money.
Scalpel or knife: A small stainless steel scalpel can be purchased at a farm supply store for less than $2-. Or use any sharp knife.
Plastic 30-Gallon Garbage Can: Used to soak the pots and flats in bleach solution to sterilize them. The kind with wheels is better.
Plastic Kitchen Bags: The cheapest clear or white 13-gallon bags work great. The white ones let through all the light that is needed for
cuttings, so don't spend much time looking for clear bags.
Bleach: Chlorine laundry bleach. Use a half a gallon in the 30 gallon can to sterilize pots and flats.
Pot Labels: We use 5 inch nursery pot labels. We buy them by the thousand and they cost $20 to $25 per thousand. .
Sharpie Marking Pens: Black Sharpie marking pens work fine. The Iindustrial Sharpie is better and is available at an office supply
store like Office Max or even cheaper at Lowes.
Germination Soil Mix: We use a germination sold by Sun Gro Horticulture. It comes in 2.8 cubic foot bags and costs about $18.00-.
We have used Sunshine Mix numbers 3 or 4 with success also, but it is more expensive. Others use Whitney Farms products. All are
based on peat moss with vermiculite and/or perlite and lime and most importantly a wetting agent so
it will absorb water quickly. All are also sterile so that the cuttings will not suffer from diseases such as damping off. Germination mix
is a much higher-grade product than a standard potting mix, which is too coarse for cuttings.
Green House Fertilizer: We use 20-20-20 green house fertilizer with trace elements. We bought Jack’s at the Wilco farm store and it
was $40.00 for 25 pound bag. Miracle Grow products work well too and come in much smaller quantities.
More detailed instructions:
Before you start: It is imperative that all pots and flats need to be clean and sterile. We soak the pots and flats in a bleach solution for a
day or so. We use 30-gallon plastic garbage cans that have about a half of gallon of laundry bleach added to the 30 gallons of water.
New pots or flats do not have to be sterilized (but it never hurts). Knives and scalpels can be soaked in a bleach solution but
remember that if they are left in the bleach solution for longer than a few hours, the bleach will corrode stainless steel. The key to
success in growing cuttings is using sterile pots and flats, and sterile potting mix.
(1) On about March 1st, tubers or pot tubers need to be potted in a potting mix into sterilized 4-inch pots(or bigger). It is not necessary
to use expensive potting soil for the pots. But do not use soil or compost from your garden. Initially, the tuber eye should be placed
under the soil. All pots should be labeled. It is handy to have some larger pots for large tubers. Some people place the tubers
horizontally in flats but we find that it is harder to label the tubers and also harder to water them. Also if you desire to plant the tuber in
the garden after taking cuttings it is more difficult to do so when using flats. There may be some controversy about whether a tuber that
has produced cuttings should be planted in the garden. We have done so with few problems.
(2) The watered pots are placed on a shelf or bench about 6 inches from a florescent light source. We grow the cuttings in our
unheated basement. We use plastic shelf units on which we have attached the florescent lights. The pots need to be watered
regularly and most of them will sprout in 2 to 3 weeks at 70 degrees or so.
(4) In about 2 to 3 weeks the tubers will have 2 to 3 inch shoots. We like to take cuttings when the sprouts are about 2.5 inches long
but longer or shorter will work too. We have accidentally broken off a 1-inch sprout and were successful in getting it to grow roots.
Sprouts as long as 6 inches or so can also be rooted but they do not fit easily into the plastic bags that we use to keep the cuttings
moist. Another type of cutting material is the so-called "white cutting" which is a cutting taken off a tuber that sprouted in storage. They
will work if they are not too long and
convoluted. They seem to take longer to form roots. This is probably because they do not have any chlorophyll to produce energy for
the development of roots.
Another type of cutting is a leaf cutting, which is taken from a dahlia plant that has grown to 12 inches tall or so. Unlike tuber cuttings,
you use the material form a leaf node to produce a new plant. Leaf cuttings take longer to root and longer to develop into a full size
plant. The plant that develops is very small it takes weeks longer to grow than a regular cutting.
(5) Cuttings are taken from the tubers. We use a small disposable surgical scalpel to cut
the sprout off the tuber. You should cut as close as possible to the tuber but not cut into the tuber. In other words, cut the sprout off the
tuber just above the tuber about 1/32 of an inch above the tuber. If you cut off all of the “eye” it will not send up any more sprouts. The
next sprouts will appear from the site where you removed the cutting. Usually two sprouts grow from that spot.
(6) Cuttings are inserted into 2.5" pots filled with sterile germination soil mix. We prepare an entire flat of 2.5 inch pots and fill them
with moistened germination mix. The cutting is planted into the pot by first inserting your finger into the soil to make a small hole and
the cutting is placed into the hole. We plant them deeply and the bottom of the cutting is near the bottom of the pot.
(7) The pots are watered and placed into a sterile flat. We then water each of the pots with an additional tablespoon of water. Be sure
that the plastic flat is clean and sterile. Our flats hold 36 pots. Don't forget to label each cutting with a 5" pot label.
(8) The flat, full of cuttings, is inserted into a 13-gallon kitchen bag and tied shut. A regular plastic 13-gallon bag fits the flat just right.
Even though the bag may be white, plenty of light gets through to the cuttings. The plastic bag keeps the cuttings moist. This replaces
the method of misting the plants many times per day. Since everything in the bag is sterile there is little chance that the cuttings will rot
or get fungus.
(9) The flat is placed on the shelf or bench 4 to 6 inches under the florescent lights. The lights are left on 24 hours a day. I have been
told that 18 hours is sufficient but I know that 24 hours works really well. Again, the temperature should be 68 to 72 degrees. We use a
sharpie pen to mark the plastic bag with the date we took the cuttings.
(10) After 11 days, open the bag and check the pots for roots. At our house nearly all of the cuttings have roots at 11 days. You can
determine if they have roots by looking at the weep hole on the bottom of the pot. A white root can be seen. If there is none, carefully
remove the plant and soil from the pot by putting the pot upside down in one hand with the cutting between your fingers and tap the
bottom of the pot with your other hand. The soil and plant will fall into your hand and the pot can be removed to inspect the soil for
evidence of roots.
(11) Remove the plastic bag from the cuttings and leave the flat under the lights for 7 days. This step allows the plants to get used to
being in the open but still in the even temperatures of the house. After this period, they are ready to go to the green house.
(12) Water cuttings as necessary; do not fertilize until they have been out of the bag for about a week and then only use greenhouse
fertilizer at 1/3 the normal rate.
(13) Move cuttings to the green house or cold flat or lighted window. Our green house is not really well heated. I have one 8-foot long
heat pad that works really well to give cuttings some bottom heat.
(14) When watering use 20-20-20 greenhouse fertilizer diluted to one-third strength.
(15) Optional: After two weeks or so, replant to four inch pots using a good soil mix. Advantage: the plants can grow bigger in the pots.
Disadvantages: You need to buy the larger pots, need to buy lots of extra potting soil and have lots of extra room in your greenhouse.
We do not re-pot the plants going into the garden but do re-pot some to be kept as pot tubers and to be grown in the 4 inch pots all
(17) Grow the rooted cutting until they reach 6 to 14 inches tall and then plant them in the garden. 12 inches tall is ideal. You can bury
plants deeper than they were in the pots. Dahlias are somewhat like tomatoes in that they can produce roots from leaf nodes buried
under the ground. You may get more tubers if they form on the buried stem. Also the plant will be less likely to fall over in the wind. Be
sure to water in the plants very well. The dilute greenhouse fertilizer can be used to water them in.
(18) Control for slugs or other pests as needed. A wise gardener will check for slug damage right away. Newly planted dahlias will
start growing again after a week or so. During this first week, you need to watch your plants carefully and control any damage from
(19) Grow as you would a dahlia grown from a tuber. Once the cutting is planted in the garden, it grows pretty much like a plant grown
from a tuber. Some varieties seem to grow more vigorously from cuttings.
(20) Enjoy the wonderful flowers, weeks earlier than plants grown from tubers. This is part that we like. We can count on having some
flowers by about July 15th.
R.C. Diane Brazil
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