May Gardening Calendar

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(Note: Some tasks from last month can carry over into this month due to the closeness in the season. If you have already performed any of these tasks, enjoy the feeling of having that task complete!)


  • An important note about seeding & weeding of the lawn. Often homeowners want to seed and thicken up their lawns in the spring but often forget that weed killer products of all types will hinder the germination of grass seed if applied during the same period. If both are being done, we suggest using selective spot spraying in lieu of a global lawn application when seeding is being managed. Herbicides are not suggested to be applied in the same areas of newly seeded areas for a period of 4-6 weeks.
  • Bermuda Grass will begin to sprout this month. You can use HiYield Triclopyr Ester on emerging Bermuda Grass to suppress it’s growth within the lawn. Ask an associate about application rates & frequency.
  • If you have recently applied grass seed, make sure to keep up with a good deep watering during the hotter days of the month as fescues used in our region are very sensitive to drought. For lawns that are supported by automatic Irrigation systems, use caution as to not over water the lawn. Usually 2 run cycles each week is sufficient. Long less frequent watering is more effective then frequent shorter waterings as it encourages deeper rooting as well as minimizes diseases problems.
  • Spin Trimming is a critical make or break approach for the appearance of a lawn. A proper method of spin trimming the edges of the lawn along driveways, walks, curb lines, landscape beds, etc. needs to be done using a vertical cutting angle where you are only cutting the actually overlapping grass blades keeping the grass height at 3-4” in the lawn entirely up to the adjacent material being edged against. Most spin trim more horizontally scalping a side 6-12” wide area of the lawn causing not only dieback of the grass in this region but also causing a heavy infestation of weeds within this area. Keep mower blades sharpened at least once per mowing season.
    It’s mowing season – make sure you are maintaining your grass height at 3-4″ high.
  • Most homeowners or mowing companies mow local fescue lawns too short at a 2” height. This is very stressful to lawns as the preferred mowing height should be 3-4”. Mowing too short will greatly affect the health and appearance of the lawn and does not aid in lessening your mowing interval.


  • Spring flowering shrubs that have finished their flowering are best pruned shortly after their flowering. Light pruning of small branches can be performed during all through the growing season but all heavy pruning must be done shortly after their flowering.
  • Roses of all types that are emerging from their dormancy are best to be pruned and thinned at this time. For more winter sensitive roses such as Hybrid Tea, Floribunda, and Grandiflora that may have been mulched heavily to protect the lower canes and graft area, it’s best to remove pull back the mulch to a depth of 3-4”.
  • All shrub or landscape types of roses such as Knock Outs, Drifts Roses, etc. should have been pruned in March or early spring by 20-50% of their overwintered height. If this was not managed, then it can be done anytime during the early to mid spring season or can be done following any cyclical or heavy flowering period.
  • Panicle Hydrangea such as Pinky Winky, Limelight, Little Lime, Bobo, and many more, are quickly developing their huge growth flush as they prepare for late spring flowering into the summer months. We suggest light tipping or light shearing of this new growth a couple times during mid spring in May to early June to provide a more compact habit and more branch tips leading to more flowers.
  • On spring flowering trees like Dogwoods, Cherries, Crabapples, etc, after their flowering has finished is a great time to manage any needed shaping of lowering branches, thinning congested branch areas, and raising lower branch canopies.
  • On evergreens such as Cypress, Junipers, Yews, Holly, and other coniferous & broadleaf shrubs, it’s best to utilize the heaviest time of a growth surge to ensure that shrubs are pruned by shearing or thinning before the majority of the growth flush has occurred. This has you taking charge of where you want this growth energy to go.
  • Fertilizing is most important in the spring when trees and shrubs have metabolism’s requiring nutrients to support their foliage growth and flowering needs. For general landscapes outdoors, we suggest utilizing granular fertilizers as the base of your fertilizer program. Liquid or water soluble fertilizers can be used to supplement newly planted shrubs or those that may be just weaker than normal. Talk to our associates about the proper fertilizes needed for your landscape.
  • Azaleas, Rhododendron, & Camellia are heavy and shallow feeders that really appreciate lighting more frequent fertilizer applications utilizing Fertilome Azalea, Rhododedron, Camellia Food. We suggest monthly applications during the spring and summer growing season following their flowering. A special note about a great supplement to fertilizing these flowering beauties is applying a supplemental nutrient Fertilome Liquid Iron to the soil & root area. This supplement will provide you larger and healthier green foliage.=
  • Butterfly bush are fast prolific growers and range from smaller to larger growing varieties reaching from 3-4’ up to 8-10’ tall. Often these get too large and respond great to heavy pruning which is suggested to be performed in early to mid spring. It’s often recommended to cut back yard once each spring by 50% or so. Follow this up with fertilizing with Fertilome Gardener’s Special fertilizer to produce strong flowering throughout the summer season.
  • For Roses, Azaleas, Hemlocks, Holly, and many forms of deciduous shrubs, insects such as Aphids, Lacebug, Hemlock Wooly Adelgid, soft scales, and more begin to infest and graze on the foliage and internal fluids of these shrubs. A great and easy to apply soil drench insecticide, Fertilome Tree & Shrub Insecticide Drench, is a system insecticide that is applied to the soil and root area and taken up by the shrub for a year long of insect control. No spraying or difficult to apply methods. Simply follow the instructions for the shrub or tree size and blend with a bit of water to apply to the soil and root area.


  • If you haven’t mulched in at least a year, check your mulch depth and quality. We recommend a 3-4″ mulch layer to help plants retain moisture in the summer heat and suppress weed growth, to hold in moisture, and to enhance the appearance of your landscape.
  • Weed control can be one of the easiest or often one of the most dreaded forms of gardening tasks for the general landscape. A weed infested landscape can have a severe affect on the appearance of even the best looking landscapes or gardens. The best advice we can give is to never allow it get out of hand. Allowing weeds to get larger and unsightly also creates a strong production of weed roots and seeds to continue to spread their existence. Spot spraying on regular intervals is a proven trick to keep weeds at bay. Purchase and dedicate a small, easy to carry, 1-2 gallon pump compression sprayer to a non selective herbicide such as Hi-Yield Kill-Z-All Weed killer. Grabbing this sprayer with this liquid herbicide solution and walking thru the gardens and spot spraying small weeds every 1-2 weeks is a proven way to never let them get too large. Depending on the size of your landscape, often this can be accomplished by 15 – 30 minute intervals rarely even having to even pulled the killed weeds minimizing hours and hours of weed pulling tasks.


  • If you haven’t done so already, prep your garden beds by tilling the soil and replenishing any areas that seem low with a good quality topsoil and soil amendment such as Daddy Pete’s Composted Cow Manure or Baccto Organic Veggie Mix.
  • Start that vegetable garden! We are past the frost danger so you can plant Tomatoes, Cucumbers, Peppers, Corn, & more for a lovely summer harvest.
  • Plant sweet potatoes later this month. Sweet potatoes are not fond of cool soil temperatures and soil temperatures have typically sufficiently warmed up to the later part of the month.


  • Provide extra tie or stake support for vining plants such as Honeysuckle or Clematis as they begin to grow new shoots and tendrils. 
  • Early Spring blooming stalks that have now deteriorated can be gently pruned and removed. (Lungwort, Yucca, and other early Spring bloomers)


  • If you haven’t already, prep your flower beds by tilling the soil and if necessary a good quality soil amendment such as Daddy Pete’s Composted Cow Manure
  • Replenish your containers with some fresh potting soil
  • Fill your containers and flower beds with lots of beautiful summer flowers! There are so many to choose from and their vibrant blooms bring color and cheer to the home exterior.
  • Remember to fertilize blooming summer flowers every 2 weeks with a 20-20-20 fertilizer for a healthy plant with lots of blooms!
  • Don’t let containers dry out. Most container flowers in a sunny area need to be watered daily to keep from drying out. Container flowers in the shade can be watered less frequently. If you don’t want to water frequently, consider a flower such as Lantana which loves hot & dry weather.
  • Make sure to mulch your flower beds. Mulch is important for moisture retention and weed suppression – plus it provides a nice finished look.


  • Houseplants can be moved outdoors, if desired. You MUST transition them slowly. They will need to be placed in full shade outdoors initially and then can be slowly moved to a partial shade area where they will get a little more light. Placing your indoor houseplants into full sun outside will burn and destroy the foliage. Remember: you will need to water them more often than you would if they were indoors. Have questions? Just ask one of our friendly greenhouse associates about your specific houseplant!


 Waking up the water garden is a common things during the spring months. Often suppliers, such as Evergreen of JC, of aquatic plants and pond hardy fish will acquire their first shipments from mid April to mid May. Adding new plants and fish are among those things often done in spring but can be done at any time of the year from Spring thru fall.

  • May is the month to also acquire the tropical floating water plants such as Water Hyacinths, Water Lettuce, etc. These tropical floaters spread and multiple quickly but can’t tolerate our cooler frosts and cooler water temps prior to May. Floating aquatic plants provide great blockage of sun light assisting in reduction of algae and do also play an important role their role of an ecological balance.
  • Water garden pumps, filters, and UV lights need to be inspected and evaluated for any repairs or maintenance needed. Most filters need to be heavily cleaned at least once per year but this also depends greatly on the type of filter you may have. Ensuring that pump intakes are not clogged with debris will ensure improved pump live and performance.
  • Cleaning water gardens of their collected wastes can also vary from approach. Varying on environments, quality of ecological balance in the water garden, volume of sunlight, fish load, and feeding habits all have a great affect on the accumulation of unwanted waste debris in the water garden. Cleaning too often can be a problem and rarely should ever be done more than every 1-2 years. If a collection of bio waste & debris is present in the bottom at a depth of more than 1-2”, then a cleaning is likely needed. If no more waste is present than this, cleaning can be avoided but does vary from site to site. As one of our water garden associates for more details.
  • Start up of beneficial bacteria with one, such as Microbe Lift PL, is an important part of kick starting an ecological balance. Beneficial bacterial play an important role in removing the need ammonia and nitrites to beneficial and less toxic nitrates taking up by aquatic plants. This is one of the most important parts of a successful water garden. Ask one of our associates more about how to tweak and manage an ecological balance in your water garden.
  • Evaluating you water garden aquatic plants that are present in the water garden is important this time of year. Whether it be marginal hardy aquatic plants or other suspended ones like Water Lilies, and Lotus, aquatic plants do grow and spread quite fast and often repotting into larger containers, dividing or reducing the volume of root mass, or other forms of aquatic plant maintenance and fertilizing may be suggested. Ask our associates about what your needs may be.
  • Always keep some Dechlorinator “Pond Detox” on hand in the case of an accidental condition of overfilling with tap water. Often pond owners will add water to the water garden from their tap water source having chlorine and other metals present. Any time more than 20-25% of the pond’s water volume is added new, a dechlorinator product should be added to ensure that your fish are not killed. Chlorine in heavier volume will kill pond hard fish. Most pond owners have experienced accidentally leaving on a water hose too long to only find out that they don’t have a dechlorianting product on hand. We advise to always keep some on hand for when this may occur.

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