How to Care for Dahlia Bulbs
Dahlias come in every color but blue, with 12 different flower shapes and sizes. They range in height from 1 to 7 feet. Dahlias grow from bulbs or tubers which must be lifted in the fall in areas that have cold wet winters. Zones 7 and 8 can overwinter dahlia bulbs in the ground by mulching heavily with straw or shredded bark. Overwintering dahlia bulbs or tubers isn't hard once you have a system in place. It takes several hours to prepare a dahlia bulb for storage. If you are pressed for time temporarily store bulbs in a cool dark location until you have time to prepare them properly. Does this Spark an idea?
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Things You'll Need
- Pruning shears
- Hand trowel
- Soft bristle brush
- Sharp knife
- Indelible pencil or plastic ID tags
- Cardboard box or plastic container
- Moistened horticultural sand, sawdust or peat moss
Instructions
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Stop watering your dahlias in mid-fall or 1 to 2 weeks before the first frost date.
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Allow frost to wilt or partially kill the greenery.
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Prune back the wilted leaves and stems to 6 inches. Wait 1 to 2 weeks before digging up the dahlia bulbs. Leaving the bulbs in the ground encourages them to go dormant.
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Dig up the dahlia bulbs using a hand trowel. Don't cut or damage the bulbs. Discard bulbs that are soft or appear rotted. Healthy bulbs are firm to the touch and an even tan or brownish color.
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Use a soft bristle brush to remove as much soil as possible. Place the bulbs in a sunny spot and allow them to dry for 4 to 5 hours. Brush the bulbs again to remove dried soil.
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Trim up the dahlia bulb by removing roots using a sharp knife or pruning shears. Cut the leaves and stems to 1-inch above the eye (the place where the buds emerge).
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Divide dahlia bulbs now if needed. The bulb should be divided if the original bulb is surrounded by smaller bulbs or growths. Each piece needs one to two eyes (the place where growth emerges). Eyes are typically found on a ridge that runs along the top of the bulb. Use a sharp knife to divide the bulb rather than breaking pieces off.
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Label your dahlia bulbs by writing the variety on the bulb itself with indelible pencil or attach plastic plant ties to the stem.
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Fill a cardboard box or plastic container with a 1 to 2-inch layer of slightly moistened horticultural sand, sawdust or peat moss.
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Place a layer of dahlia bulbs on the moistened material. The bulbs should be arraigned so they do not touch. Cover with another 1 to 2 inches of moistened material. Continue layering this way until the container is full. The top layer of dahlia bulbs should be covered.
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Place the container in a basement, garage, or outbuilding where temperatures remain between 40 and 50 degrees F.
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Check your dahlia bulbs monthly. If the bulbs appear rotted they are too cold and wet. Remove the bulbs, use a sharp knife to cut away rotted sections (remember to leave one to two eyes per bulb) or discard the bulb, allow to dry overnight, use new moistened sand, sawdust or peat moss and a new container to store them. Place in a warmer location. Shriveled bulbs mean they are too warm or dry. Sprinkle with water and place in a cooler location.
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Plant dahlia bulbs 1 to 2 weeks before the last frost date in your area. Examine the bulbs before planting. Discard bulbs that have rotted over the winter.
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Tips & Warnings
You can also use several sheets of newspaper to separate dahlia bulbs in their container. Use black newsprint only and do not moisten the paper. If you have a lot of dahlia bulbs and don't want to identify each individual bulb: poke holes in a large plastic storage bag, fill 1/3 to 1/2 of the bag with moistened peat moss, add bulbs of the same variety to the bag. Seal the plastic bag and place in a paper bag or black plastic container (to exclude light) store at 40 to 50 degrees. This is not the best way to store dahlia bulbs as you might lose an entire bagful of bulbs to fungus or mold rather than 1 to 2 individual bulbs.
Be prepared to lose some of your bulbs to rot or dehydration. Mice find dahlia bulbs tasty. If you have mice in the area you are storing your dahlia bulbs line the containers with a fine gauge mesh (be sure to cover the top also) to prevent mice from feasting on your bulbs.
