Many flower directions say “deadhead”. Sounds weird!!! What is it? The definition is the removal of flowers that have finished blooming. But why, when, and which plants need this?

          Generally we deadhead to improve the looks of the plant but may be doing it to prevent the seed from maturing and then planting themselves in surprise areas.  When plants self seed, quite often I like the new arrangements they make because many times it looks better than my original plan.

          Some bulbs need to be deadheaded or the plant will spend its energy producing seed at the expense of the bulb.  I have read that tulip flowers can harbor a fungous so cut off the flower only to get rid of the disease, but leave the stem which is still green and making food for the bulb. There are many of the small bulbs that will reseed and enlarge the size of the bed. For me this has been my experience with Scilla and Grape Hyacinths. Both of them now come up by the hundreds which wouldn’t happen if I had deadheaded as soon as the flowers faded. When you clip Gladiola or Lilies be very careful not to remove any more foliage than necessary. It is busy making food to enlarge the bulb. For years the “rose people” have been giving specific directions to cut the dead rose flower back to the nearest 5 leaf that is facing out and the bud on the cane will produce a new shoot to bloom in six weeks.  Facing out is to keep the center of the rose bush from getting crowded which encourages fungous disease. Now in the last few years several people have challenged cutting off so much. A number of people trying both ways: (a) the old 5 leaf rule and (b) removing just the spent blossom to see which works best.

          Deadheading before the seeds can mature is for those people that want to control what plant goes where as well as to keep volunteer numbers down. CLEOME (Spider Flower), MEXICAN HATS, GOLDENROD, COSMOS, POPPIES, TALL PHLOX, plus others are well known for their many seeds. However, if you don’t care then let them go. The last few years I have a new plant called MEXICAN HAIR GRASS. It is not hardy here but I have many seedlings as far as 10 feet away from the parent.  I like it very much for stems that blow in the wind. It is about 18 inches high with thick blond hair. One of my paths is completely loaded with plants about 2 inches high.

          Another reason for deadheading is to urge plants to try again. One purpose in the life of a plant is to preserve the species. Therefore many, but not all plants will put out new buds after deadheading. Among these are CENTHRANTHUS, DELPHINIUMS, GLOBE THISTLES, many of the PENSTAMONS, VERONICAS (Speedwell), TALL PHLOX, and DIANTHUS. There are others requiring a more drastic action such as cutting all the way back to rejuvenate the plant.  A general rule is (a) if the flower stem is bare cut it all the way down, or (b) if the stems have leaves then cut just the tired bloom off.

          Some flowers, such as PETUNIAS bloom heavily for some time before becoming scraggly. But when they do, one can cut the entire plant back quite severely to survive another blooming session. Sometimes the packet containing seeds will recommend whether or not to deadhead. There are some plants that do their own.  For example, the very popular newer rose KNOCKOUT. Some plant tags give you instructions about deadheading.  There are a number of people who like to leave seed heads on during winter either for bird food or winter interest.

          Another closely related task to deadheading is the one in which shrubs become too wide, too tall, or just scraggly looking.  If you cut them all the way down there will be a blank space for one or several years.  The most common method is to go in and remove one third of the stems. Usually you take out the tallest, or the barest, or the oldest stalks all the way to the ground. This is best way to prune LILAC, FORSYTHIA, FLOWERING ALMOND, and some other spring blooming shrubs. This way there is no huge gap and you don’t lose all the blooms for several years. Repeat this process for the next three years and then you have a brand new plant.

For LILAC it is good to do this every year.

     You can cut the entire shrub or plant way down at once on some plants, but you lose the bloom for at least two years and maybe longer. I like to do this in late fall to SPIREA, BARBERRY, ANNABELLE HYDRANGEA, and SHRUB DOGWOOD. If you do it any sooner in the year it will stimulate new growth that will be destroyed by frost. You also need to be careful which plant you cut when. If the plant or shrub blooms in the spring on old wood, such as the FORSYTHIA, and LILAC, it must be done after flowering. Plants such as CAROPTERIS (Blue Spirea) and BUTTERFLY BUSH bloom on new wood so they can be cut down in winter or early spring. Because of our unpredictable winter, it is generally advised to wait until spring.  I have a WISTERIA in bloom now that I will cut all the way back as soon as it finishes. I will not have any bloom next year but it branches so wildly it becomes tangled and the blooms don’t show well. It will be up within a week and wrapping around its pole tightly.

Buddleia alternifolia (BUTTERFLY BUSH) blooms on old wood and any trimming needs to be done immediately after blooming while Buddleia davidii (our most common BUTTERFLY BUSH) blooms on new wood. I generally cut them all the way back after frost, put a cage around it and fill it with compost in case we have a nasty winter.  The compost is taken out in spring to spread around the plant as mulch. It also prevents many weed seeds from starting.

Copyright 2007