Gardeners Grow Together Week 15, April, 2021: Growing Dahlias
Welcome to my special gardening page for those of you who like to garden yourselves! Each week, I will make suggestions as to what gardening tasks we need to do every week during the growing season. It will help keep you on track--as well as myself!
To keep things simple, I am using the year's weekly number, Week #1 through #52 (example: the week of January 1 is Week #1), instead of specific dates.
So, come on! Let's get our hands dirty!
I am completely obsessed with Dahlias. I can't get enough of them. They come in a huge variety of flower forms, color combinations and sizes.
They sport every color, except blue, from white to almost black, soft pastels to vibrant fire colors, and beautiful blends of all of the above, as well as striking contrasting splashes of colors in the same flower.
They come in array of flower forms, too - Decorative, Ball, Cactus, Anemone, Collarette, Waterlily and Single; and vary in size from 1 1/2" tiny ball types, to huge 12" "Dinner Plate" size! The plants come in all sizes, too, from 12" to 7ft tall.
Propagating these beauties is so very easy, too! The amazing thing is that you can get big, mature, blooming plants in the first year from seed and cuttings.
Starting from Seed:
Growing Dahlias from seed can be a real (and exciting) adventure, because you have no idea what you are going to get in the end! Dahlias are never "true" from seed; however, you are guaranteed a delightful surprise with every bloom. There really is no such thing as an ugly Dahlia!
You will need:
Dahlia seed. Available through seed catalogs or on line. Sometimes they can be found on the seed racks at garden centers.
Seed cell trays or a flat tray at least 3” deep
Seed starting mix
3 ½ inch pot
Starting from seed couldn't be easier. They can be started in cell trays or just in a flat tray of some kind, as long as it is at least 3" deep. Fill them with a good seed starting mix.
The seeds are long and spike shaped. I like to stick them in the soil on end and push them in with my finger until just covered. If using a flat tray instead of cell packs, plant the seeds at least 3” apart. Water thoroughly, and place them in a warm place, under grow lights or a sunny window sill. The seeds will germinate very quickly, within a few days.
Once the plants have at least one set of "true" leaves, carefully prick them out of their seed starting containers and transplant them into 2-1/2" to 3" pot. Be very gentle when transplanting, as they will be forming tiny tubers, which you do not want to damage or break off.
How often to transplant them into larger and larger containers depends on how early you start your seeds. They cannot be planted out in the garden until all danger of frost has passed. I usually go up a pot size or two at least once a month until planting outside.
When they start to bloom in the garden, mark the ones you like the best to save for next year. You can propagate those plants from either cuttings or tuber divisions next year. Be sure to save seeds from the other plants for next year's adventure!
Starting Dahlias from Cuttings:
If you want to duplicate your favorite Dahlia, take cuttings! Dahlias root from cuttings very easily, as well. They will produce identical clones of the mother plant.
What you will need:
A very sharp, clean and sterile knife, or Exacto knife.
Good potting soil
3 1/2” pot for cuttings
A pot just large enough to hold the mother tuber
Rooting hormone powder (optional)
Clear plastic bag
Dahlias are purchased as dormant tubers, either in large clumps or single tuber divisions. I usually start my tubers growing in February or March in the house to get cuttings to ensure blooms the first year; however, you can do it any time during the growing season. If you start them too late, though, you may not get flowers the first year.
Place the tubers in a shallow pot or tray filled with slightly moist potting soil. Plant them shallowly with the “neck” and growing eyes above the surface for easy access. DO NOT water again until you see growth starting. Your tubers may rot, otherwise! Some will sprout right away, others may take a month or so to wake up from their winter sleep.
Once the sprouts are about three inches tall, take a sharp knife and cut them off right at the surface of the tuber, getting a tiny bit of the tuber with the cutting. Cuttings can be taken from anywhere on the stem, but if you get a bit of the tuber along with the sprout, you will have much better success with rooting.
Don’t worry about hurting your tuber. It will produce several new sprouts from where you made the cutting, giving you more cutting possibilities!
I like to use a 3 1/2” pot for four cuttings. Fill the pot with a good potting soil. Use a pencil to poke four holes in the soil.
Moisten the cut end of the cuttings and dip just the ends in the rooting hormone powder. Using the hormone powder isn’t required, but you will have better success if you use it.
Cut any leaves in half to cut down on transpiration of water through the leaves. Gently place the cuttings in the holes, try not to wipe the rooting hormone off the stem. Make sure you use a plant marker, indicating the name of the variety, mature height and flower type. All Dahlias look the same until they bloom!
Cover with a plastic bag with a small hole cut in the top for ventilation. I usually use quart or gallon sized zippy bags, because they are substantial enough to stay upright without support.
Once new growth starts on your cuttings, congratulations! You have successfully rooted your favorite Dahlias! Now it’s time to move them on to their own 3 1/2” pot. Again, carefully remove them from the communal pot and gently separate the plants, being careful not to break the roots or tubers.
After marveling at the remarkable tuber development in such a short time (as I know you will!), place each cutting into its own 3 1/2” pot. Again, move them up a pot size (or two) every month until planting time, after the danger of frost has passed.
I will be giving more tips during the growing season. I will show you how to plant them out in the garden, how to fertilize, and how to "pinch out." I'll also explain cut flower care, and how to wrap up for winter storage. So please stay tuned!
Dahlias are fun, rewarding, and fascinating to grow. Just be careful! They can be terribly addicting!
Now, let's get busy! If you have questions, put them in the comments below!
Valmont Valley Farm
Where Beautiful Magic is Always in Bloom
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