Instructions for How to Grow and Store Dahlias in New England

Planting Indoors

·         Select the dahlias you want in late winter.  There are a growing number of garden centers, hardware stores and even supermarkets that sell the tubers.  There are also several websites which offer huge selections. 

·         Start growing the dahlias (tubers) indoors at the beginning of April.  These plants can grow as tall as 5 or 6 feet and need a long growing season.  Since they bloom late in the season, you want to make sure they bloom before the first frost. It is helpful to give them a head-start.

·         Place the tubers in a container (recycled plastic cartons) with enough potting soil to cover the entire tuber, with either the beginning growth or “eye” placed near the surface.  If a stem has already appeared before planting, make sure it is not buried.  The stem will be a whitish color.  If there is no stem, one will eventually appear from the “eye”.  The root that you are planting is called a “tuber”, and the “eyes” are the same as the “eyes” on potatoes.
                                                                                                               

·         Water the soil just a little bit. The tuber does not require a lot of water, and should only be watered after growth appears.  WARNING:  Too much water will rot the tuber!  The soil should have moisture and not be dry.  It should not be wet, either. Water just a little bit after growth appears.

·         Place the tuber either in a sunny window or under a grow-light.  The tuber does not require light around the clock, just from morning to early evening. 

·         The tuber will soon show a stem.  At first the stem will appear white, but with the light, it will quickly turn reddish in color.

·         Soon, leaves will appear! You will see your plants grow! Water lightly.


Growing Outdoors

·         The plants will need to be hardened off in mid-May.  This process takes about a week.  This requires bringing the dahlia plants outside for increasing lengths of time, exposing them gradually to warmer and cooler temperatures.  Do not let them stay outside on cold nights.

·         After any danger of frost is gone, the plants may be transplanted outdoors. The frost-free time here in southern Massachusetts is usually about Memorial Day weekend.

·         Plant the dahlias in sunny locations.  The soil temperature should be around 60 degrees. The soil should be well-drained, with a pH of 6.5-7.0.  Mulching is beneficial.

·         Many dahlias require staking.  You may place a stake at the time of planting to avoid damaging the tubers later on.

·         Dahlias should be fertilized, but with a fertilizer low in Nitrogen (5-10-10, for example).  Apply fertilizer one month after planting, and then side-dress monthly.

·         THIS IS IMPORTANT:  Make sure you label your plants by name or color, to make storage later on easier.

·         Earwigs and slugs can be a problem for dahlias.  Begin to treat plants as soon as leaf damage becomes noticeable. Also, slug bait can be applied at time of planting.

·         Dahlias will begin to bloom in July or August and continue until the first frost - if the dead blooms are continually removed. Make note of the day when the frost comes and kills the blooms.  This is usually in October.  Do not dig up the tubers immediately, as they are not yet dormant.  It will take about 2 weeks for the tubers to go dormant.

·         Dahlias are hardy to Zone 8.  This means that in New England, tubers have to be dug up and stored in a garage, shed, or basement until the spring in order to preserve them.



 Storing Indoors

·         Dahlias are hardy to Zone 8.  This means that in New England, tubers have to be dug up and stored in a garage, shed, or basement until the spring if you want to preserve them

·         Two weeks after the first frost (November), it is safe to dig up the tubers.  You will find that the tubers multiplied in number, especially if you fertilized them!  Be sure that you tag the plants with something to identify them.  After the frost, it will be impossible to tell one brown dahlia plant from another.

·         Take the mounds of tubers to be washed off with a garden hose.  Before cutting the stem, be sure that there is a label on it. Cut off the stem, leaving about 6 to 8 inches.

·         17 – Leave the mounds of tubers to dry in the garage for a day or two.

·         Find a cardboard box in which to store the tubers.  You may want to take a sharpie and mark the name of the dahlia or the color on the tubers. This will not hurt them.

·         After placing the dried tubers in the box, completely cover them with peat moss.  Place some plastic (bags) on top to keep too much air from getting in and drying the tubers out.

·         Place the tubers in a place where the temperature is cool but not freezing.  Ideally, they should be stored in a place that is in the low 40’s and dry.  Basements, porches and garages are good places.  Check on them once or twice to make sure they are not drying out.



                                                                                              








 

c  Donna Leone, Master Gardener
                                                                                                                                www.leonegarden.blogspot.com


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