Deadheading is the simple act of removing spent blooms from plants, may it be annuals, perennials or shrubs. For some plants it is very necessary, and for others it is totally unnecessary.
For example, most spring bulbs benefit from the process if they are to store up energy for the next year's blooms. Remove the spent blooms, but leave the leaves to photosynthesize and die back naturally. If this looks untidy, hide by over-planting with other spring plants. Daffodils do not benefit from deadheading but should also be left to die back naturally.
Many perennials bloom only once a year. For these, deadheading is an act of tidiness. Other perennials can re-bloom the same year if deadheaded after their first blooms fade. Watch your plant labels carefully for plants that can re-bloom.
Annuals are used for all-season color, but there are some that require deadheading to continue to flower. For example, annual salvias tend to die back if not kept "pinched" religiously. Old-fashioned petunias require deadheading to keep blooming, while newer forms such as "wave" varieties will keep blooming and hide their spent blooms with new growth. Geraniums benefit from deadheading and look tidier.
Many shrubs look tidier if deadheaded, while other shrubs have blooms that dry nicely and prolong the interest of the plant into multiple seasons. Still others benefit from deadheading.
Pruning shrubs
There are several things to consider when you want to prune shrubs, including the type of tools needed, pruning technique, type of shrub to be pruned, results you desire and when to prune.
First, tools. Hand shears are a necessity with any kind of pruning. Sharp by-pass pruners, or scissor-like, are best for the health of the plant. Lopping shears are handy for larger branches up to about 1 inches. Anything larger would require a pruning saw.
There are three basic pruning techniques. "Heading" is cutting all of the branches back to just above a healthy bud. This reduces the size of the shrub while leaving a live bud from which new growth can begin. "Thinning" is cutting a branch either all the way to the ground or to where it joins a trunk or another branch. "To the ground" is cutting all of the branches to just above ground level; there are a few deciduous shrubs that benefit from this type of pruning, but more later on this.
If it is a needle evergreen like yews, arborvitae and junipers or broadleaf evergreen like boxwood or some hollies, the first two techniques can be used separately or together. If you have shrubs that have been shaped repeatedly, they may have developed a "dead zone" in the center of the shrub. I have seen some evergreens that are 4 feet overall but with only a few inches of green on the outside of the shrub - everything inside looks dead and leafless. When this occurs, use both techniques to open the surface in spots to get light into the center of the shrub so new shoots can develop from the inside.
Always remember when trimming junipers there must be green foliage on each branch when pruned because they seldom recover from pruning to bare branches. Yews, though, can recover from more severe pruning up to 50 percent of their size.
Pines are trimmed in early spring before their growing tips, called candles, begin to elongate into needles. By trimming the candle by up to half, you can control the size and shape of pine trees and shrubs.
Evergreens should be pruned in spring, sometimes needing a second pruning in early fall. But never prune evergreens if the temperature will drop below 35 degrees or above 90 degrees during the following week, as tender, newly-exposed shoots can turn brown in heat or frost.
Deciduous shrubs are those that lose their leaves in winter. There are basically two types: those that bloom in early spring, which set their flower buds for the next year during the summer and fall of the previous year, and those that bloom in summer or fall.
The best time to prune spring-blooming shrubs is immediately after their blooms fade. This will give the shrub time to set their blooms for the following year. Some examples are forsythia, lilac, mock orange and white spirea. Use either the heading or the thinning method of pruning for these shrubs. The third method of pruning to the ground can be used on spirea and forsythia if they have become too large.
Later-blooming shrubs generally produce their flower buds on new growth in the spring for that same year. These shrubs should be pruned in winter or early spring before new growth begins. Some examples are pink spirea, beautyberry, butterfly bush, rose of Sharon and crepe myrtle. Use either of the heading or the thinning method for these shrubs also; the "to the ground" method can also be used when a shrub has become excessively large and unruly.