In May planting begins in earnest. Your tools should be well cleaned and oiled, ready for use. Remove any heavy winter mulch you have laid down to allow the soil to warm up (but keep some stored in case you need it). You should allow your seedlings to harden off now. Set them outdoors for graduated lengths of time so that they may slowly adjust to the more irregular outdoor climate without shock. In the initial stages of transplanting or sowing seeds, keep an ear sharply attuned to the weather report. May is still subject to rapid drops in temperature. A supply of hot caps on hand may save your seedlings from a sudden frost. Frost-free dates range from late April to an almost sure mid-May.
TRANSPLANTING. It is vital to prevent the delicate roots of seedlings from drying out while transplanting. If your schedule permits, transplant on cloudy or even rainy days. Have a supply of manure tea on hand to give weak plants an additional boost and to increase the size of foliage in general. It is essential from the very first to remove the dead flower heads from annuals in order to insure continued, more prosperous blooming.
SOWING SEEDS. It is a good idea to stagger the planting of many vegetable crops. This technique enables one to enjoy one’s crop at its prime over a series of weeks without being overwhelmed by an immense harvest all at once. This is particularly true with a crop such as radishes which is rather limited in usage and appeal.
VEGETABLES. Asparagus should be in season this month. After six weeks of cutting, allow the plants to grow into feathery bushes to provide nourishment for next year’s crop. Identify your bed by stringing off dormant plants at this time. All your cool-weather crops can be planted in the beginning of May, but it is a good idea to wait until mid-May for the planting of your less hardy crops such as tomatoes and summer squash. Remember to keep all plantings thoroughly watered during this crucial transplanting period.
ANNUALS. After your annuals – alyssum, ageratums, calendulas, marigolds, petunias, and sunflowers have reached a substantial height pinch back the growing tip of each plant, unless it sends up a central flower spike such as snapdragon or salvia. This will help prevent legginess and promote a more lush growth. Half-hardy annuals may be sown now, but hold back on your impatiens, zinnias and nasturtiums. While sowing seeds (or planting seeds), be careful not to disturb late maturing perennials. Proper labeling
of plant sites and a yearly garden plan are two good ways of avoiding this hazard. For large flower heads, you must have a well-fertilized, drained and balanced soil. On the other hand, experiment to see how prolifically some annuals bloom in unimproved soil. Certainly, nasturtiums and morning glories like sandy soil and marigolds have been found to flower well in unimproved brick dust. Portulaca, alyssum and the perennial sedums are some of the other numerous arid soil plants.
PERENNIALS. May is the month to sow perennial seeds for next year; also biennials such as foxglove, canterbury bells, hollyhocks, gloriosa daisies. The plants will be ready to bloom in fall or early the following spring. Many perennials will bloom a second time after the stems of the first flowering are cut down. Plants benefiting from this treatment are anemones, asters, yarrow, delphinium, lilies, phlox, and chrysanthemums. Fertilize your rock garden and see that it is kept well weeded. Make sure that peonies are well fed with phosphate and potassium and remove the small buds toward the end of this month leaving the largest to flower.
BULBS. Spread bone meal and wood ashes around spring-flowering bulbs, but do not cut back foliage until it has completely withered. The leaves are essential for the flowers of next spring.
SUMMER BULBS. Late blooming summer lilies may be divided at this time but be sure that the pH of their new site matches the old and that the soil is well drained.
SHRUBS. Remove the seed pods from rhododendrons, azaleas, andromeda, leucothoe and lilacs but be careful not to cut the leaves which are essential to all the functions of growth. Feed flowering shrubs before and during their bloom. Remove faded flowers immediately. Toward the end of the month you may prune and shape the shrubs that have finished flowering. In general, preserve young growth and cut back the old, woody, unmanageable branches of spiraea, weigela, honeysuckle and forsythia. A good way to start pruning these shrubs is to judiciously harvest some flowering branches. All your shrubs
should be fertilized at this time. The rose-of-sharon should be pruned this month – before it leafs out – in late spring. The beginning of May is perhaps not too late to trim evergreen hedge shrubs, such as Yew and Hemlock, before the new growth appears. Otherwise it is best to delay trimming until the end of July when the new growth has matured.