May is the Month to…..

•    Plant flower and vegetable transplants.  While gardeners anxiously await the typical last frost date in order to set out tender species, there is more to think about than whether or not your prized crops will get nipped by a cold night.  Another key consideration for the annual vegetable garden is rotation; as in what gets planted where.  Rotation is an important practice that helps prevent unwanted pests and diseases from accumulating to devastating levels.  Basic rotation involves not planting a species from the same family in the same location more than once every three years.  The most common vegetable garden families include Solonaceous plants (tomatoes, peppers, potatoes), Cucurbits (squash, cucumbers, melons), Brassicas (broccoli, cabbage, cauliflower, kale), and Legumes (beans, peas).

•    Fertilize the lawn, especially if there has not been a fertilizer application yet this season.  Nutrient availability is best coordinated with periods of vigorous growth, making the importance of spring fertility second only to late summer in New England.  Fertilizers should have a higher percentage of slow release nitrogen later in the spring, and applications should be avoided altogether once the heat and drought stresses of summer set in.  Fertilizers should only contain phosphorus if a deficiency has been demonstrated by a soil test, or if being applied in conjunction with seeding or overseeding.

•    Begin thinking about white grubs.  In this region, the most common approach for dealing with grubs is a preventive, or “season-long”, type application.  If grub damage or related foraging is present in the fall or spring, a preventive material will not control the mature populations present at those times.  Instead, the objective is to have the material in place when the next generation of grubs hatches in late-July and August.  Preventive products that contain chlorantraniliprole as the active ingredient take 60 to 90 days to fully activate in the soil, so are therefore best applied during the month of May.  Other commonly available preventive materials (eg. Imidacloprid) take much less time to activate and are best applied in July.  Any grub treatment should always be watered-in according to label directions.

•    Ensure that mower blades are sharpened up for the season.  Did you know that grasses ‘mow’ differently depending on species?  Grasses with more lignified shoot tissues, such as ryegrasses, do not mow as cleanly by nature compared to grasses that have less lignin in their leaf blades, such as bluegrasses… meaning that the effects of a dull mower blade will be magnified with certain species.  It isn’t all about appearance, however.  The jagged, tearing cut of a dull blade can actually increase water use significantly when considered on the scale of an entire property, leading to more stress on the lawn, the pocketbook, and increasingly scarce water resources.

•    Scout Japanese andromeda, azaleas, rhododendrons and hawthorns for lacebug infestation.  Lacebug damage typically occurs as yellow stippling of the foliage and numerous brown spots (lacebug excrement) on leaf undersides.  While this injury is not immediately threatening, plant aesthetics can be significantly impacted and plant vigor can be measurably reduced over time.  Plants on sunny sites are more susceptible to lacebugs.  The insect overwinters as eggs embedded on the undersides of the foliage, and hatch normally begins in late May.  After hatch, a carefully applied horticultural oil or insecticidal soap spray directed at leaf undersides can be very effective at reducing populations below damaging levels.

•    Get serious about tick bite prevention.  May is the month that folks return to the landscape in earnest, greatly increasing the probability of crossing paths with ticks that can transmit serious infections such as Lyme disease or anaplasmosis.  Steps such as avoiding tick habitat, showering after outdoor activities, and daily tick checks are crucial, but one of the best ways to protect yourself is through the appropriate use of repellents. The most effective current repellent approach involves the active ingredient permethrin, which is used to treat clothing and footwear, and the effectiveness typically lasts through multiple washings.  Sprays and kits are available to treat clothing at home, pre-treated clothing is available, and services exist that provide ‘to order’ treatment of clothing items as well.

•    Prune spring flowering shrubs… AFTER flowering.  While late winter is the traditional pruning time for many tree species, the same approach is not appropriate for some of our most treasured spring bloomers.  For shrubs that bloom on ‘old wood’ (i.e. last year’s growth), pruning in late winter translates to removing buds that would otherwise bloom shortly thereafter.  Instead, the correct practice is to prune these species as soon as possible after bloom concludes, leaving ample time for new growth in the current season and helping to ensure an impressive bloom in the following season.  Examples of species that benefit from pruning after flowering include viburnums, azaleas, rhododendrons, lilacs, Pieris spp., and Weigela spp.

•    Do NOT remove foliage of spring flowering bulbs… until withering occurs.  Along similar lines as the previous tip, it is imperative to leave the foliage of spring flowering bulbs intact after flowers fade.  While it is tempting to remove foliage to keep things tidy or to make way for new plant material, the foliage continues to photosynthesize.  This activity produces the sugars that will be stored to enable emergence and flowering the following spring; therefore, removing foliage could jeopardize the bulb.  To further pamper your bulbs, make a high phosphorus fertilizer application (bonemeal is a good source) when flowering ends.

•    Get a jump start on weeding.  May is a great month to spend some time pulling garden and landscape weeds, as infestations have not yet become overwhelming.  Every weed removed now that doesn’t go to seed is an investment in fewer weeds in the current and future seasons.  Weeds are easiest to remove when the soil is moist.  Many annual weeds are shallow-rooted, and pull relatively easily. They can also be smothered with mulch at this time of year.  Spend a little more time on perennial weeds – all of the underground portions of the plant must be removed or the plant is likely to sprout again.

•    Set up hummingbird feeders for the season!  Hummingbirds return from their southern migration by late April/early May in most years, so the best time to have feeders ready is by the first week of May.  According to the Massachusetts Audubon Society, feeders should be cleaned and re-filled at least once a week to prevent mold growth.  Also, if ants invade your feeder, don’t sweat it… hummingbirds actually eat both nectar and insects.