May Gardening Calendar Header

Note: Some tasks carry over from April into May so if you have already performed them then just mark that off the list!


  • 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. If you applied grass seed this Spring, make sure to keep up with deep watering during the hot days of the month as fescues used in our region are susceptible to drought. Long less frequent watering is more effective then frequent shorter waterings as it encourages deeper rooting as well as minimizes diseases problems
  • If you applied grass seed this Spring, make sure that you continue watering during the hot days of the month (and summer). Fescues in our region are susceptible to drought. Watering less often and longer is better than frequent short watering. Deep watering encourages deep roots and helps minimize disease. Watering in the morning is best as evening watering can encourage fungal issues.
  • It’s time for Step 2 of the 4-Step Lawn Care Program utilizing Fertilome Weed Out Plus Lawn Fertilizer, this is a broadleaf weed killer and fertilizer for those pesky weeds and summer lawn health. You can also spot spraying with Fertilome Weed Out. We suggest one keeping a small 1-2 gallon pump spray dedicated to a selective lawn herbicide for spot spraying selective weeds when needed.
  • 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. Bermuda grass is a stubborn weed that is difficult to get rid of so the goal is to supress it through the growing season and sow grass in the Fall to replace.
  • It is important to spin trim/weed eat correctly. A proper method of 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 and cut a 4”+ wide area of the lawn very short causing not only dieback of the grass but leaving open space for weeds to overtake.
  • Keep mower blades sharpened at least once per mowing season & mow at a minimum of 3″ tall but 4″ is preferred. Most homeowners or mowing companies mow local fescue lawns too short at a 2” height. This is very stressful to lawns & 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. Feed Roses if you haven’t already. Roses are heavy feeders and will appreciate some Espoma Rose Tone.Read more on Rose care here.
  • All shrub or landscape types of roses such as Knock Outs, Drifts Roses, etc. should have been pruned in March-April by pruning back to 20-50% of their overwintered height. If this was not done then it can be done anytime now or you can wait and do it after a heavy flowering period.
  • Panicle Hydrangea such as Pinky Winky, Limelight, Little Lime, Bobo, and others, are quickly developing a big growth flush as they prepare for flowering. We suggest light pruning of tips 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 which will bring 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, sheared, or thinned before the majority of the growth flush has finished. By pruning now, you can control where the plant puts energy into growth.
  • Fertilizing is most important in the spring when trees and shrubs require nutrients to support their foliage growth and flowering needs. For general landscapes outdoors, we suggest granular fertilizers as the base of your fertilizer program. Water soluble fertilizers can be used to supplement newly planted shrubs or those that seem weaker than normal. We recommend Fertilome Root Stimulator). Talk to one of our team members about the proper fertilizers for your landscape or specific plants.
  • 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 bushes 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 of these shrubs. A great and easy to apply soil drench insecticide, Fertilome Tree & Shrub Insecticide Drench, is a systemic insecticide that is applied to the soil and root area and taken up by the roots to provide a year long insect control. No spraying or difficult to apply methods and only needs to be applied once a year. 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.
  • It’s a great time to plant trees & shrubs! Try adding some native varieties for pollinators and birds.
  • You can apply Fertilome Tree & Shrub Drench as a systemic insect control. Each application lasts for one year and it’s simple to mix and apply.


  • 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.
  • Sow wildflower seeds
  • Clean and refresh your birdfeeders and birdbaths.
  • Put out specialty birdfeeders such as Oriole feeders and refill with orange slices. (The color orange actually draws Orioles in!)


  • 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 Nursery Blend, Topsoil, or composted cow manure.
  • Start that vegetable garden! We are past the frost danger so you can plant Tomatoes, Cucumbers, Peppers, Corn, & more for a lovely summer harvest.
  • Sow vegetables seeds for those requiring it such as carrots or for those you want to grow from seed.
  • 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.
  • Hill up the soil around your potatoes and feed with a high nitrogen fertilizer.
  • Plant herbs in the herb garden.
  • You can also prune back by 1/3 any larger perennial herbs such as Rosemary or Lavender jsut don’t prune back too far to avoid damaging the plant.
  • Plant tomatoes deep for strong plants. You can remove the lower leaves on taller/leggy tomato plants and bury the stem up to the new lowest set of leaves. This will create a stronger root system. Don’t forget to fertilize!
  • Low on space? Try container vegetable gardening. Grow bags and inexpensive black nursery pots are a great choice to grow veggies when you don’t have a lot of garden space.
  • Build a raised bed. There are a number of ways you can easily create raised beds and they are a great way to have a successful garden.
  • Sow your Sunflower seeds every 10-14 days to keep a crop always blooming in the summer.


  • 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)
  • Fertilize with Evergreen’s Bloomkote slow release fertilizer by applying at appropriate rates around most perennial plants.
  • It’s a great time to plant and add more perennials to the garden!
  • Consider adding some native pollinators plant to the landscape.
  • Stake taller perennials such as Peonies, Delphinium, & Hollyhock.


  • 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 Nursery Blend.
  • Replenish and refresh your containers with some fresh potting mix. If reusing last year’s potting soil, make sure to dump it out and loosen it up and add in some of our Bloomkote slow release fertilizer and any additional potting mix that is needed.
  • 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 in containers every 2 weeks with a water soluble fertilizer such as Fertilome All Purpose 20-20-20 or Fertilome Blooming & Rooting 9-59-8 for a healthy plant with lots of blooms! Hanging baskets will benefit from weekly fertilization, if possible.
  • 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!
  • Feed your Citrus plants with a citrus formulated fertilizer.


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 De-chlorinator “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 de-chlorinator 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 de-chlorianting product on hand. We advise to always keep some on hand for when this may occur.

Have questions about a specific plant or issue you have? Just contact The Green People and we will do our best to help you succeed!

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