As spring’s unpredictable weather drifts into summer’s expansive warmth, May offers the perfect opportunity to prepare for a flourishing summer garden. Longer days and hotter temperatures mean your plants are bursting with energy and in need of your attention to ensure abundant harvests.
Pruning, staking, trellising, and fertilizing are just a few of the tasks you should cover this month. The soil should finally be warm enough to plant all your summer crops outdoors. You can direct sow seeds in any spaces you missed. Most importantly, this is the time to check up on your irrigation system and mulch your beds to ensure your garden can withstand the long, sunny days ahead.
Let’s dig into 13 essential May gardening tasks for any zone.
What Gardening Tasks Should I Do in May?
May marks a crucial time to nurture your growing garden.
On the cusp of spring and summer, May is a crucial window of opportunity to tend your plants as they eagerly grow in the warming weather. Pruning, deadheading, trellising, staking, and sucker removal ensure tidy growth and plenty of focus on the flower or fruit production you desire.
For many zones, this is the essential time for transplanting tender summer annuals like tomatoes, squash, cucumbers, peppers, sunflowers, and marigolds. If you forgot to start seeds indoors, the soil should be warm enough to direct sow most warm-weather crops outside. Northern growers may need row cover to protect frost-sensitive plants from cool nights. Southern gardeners can apply shade cloth to prevent bolting and heat stress during hot days.
It is also very important to check your irrigation system and mulch the soil to conserve water and ensure your plants are protected against potential droughts during the hottest months. Installing drip lines or soaker hoses is a great way to save water this summer, decrease weed pressure, and reduce the risk of foliar diseases from overhead watering.
13 Tasks for May Gardeners
In most parts of the Northern Hemisphere, May gardens are in full bud or bloom. While far northern zones may still face chilly nights, temperate and subtropical areas are typically bursting with color. Make the most of this bridge between spring and summer by getting ahead on these garden tasks.
Transplant Summer Crops
Seize May’s prime time to transplant your warm-weather crops.
May is prime time to transplant your warm-weather crops. Zones 8 and warmer might already have crops in the ground, but zones 5-7 need to prioritize transplanting throughout May. Even in frigid zone 4 (with a last frost date around May 27), this month is a crucial window of opportunity to establish your long-lasting summer annuals.
Crops like tomatoes, cucumbers, zucchini, and peppers will supply continuous harvests throughout the hot months. If your growing season is short, it is particularly important to give your crops a head start. This way, they have plenty of summer days to mature and produce the largest yields possible.
Checking Soil Temperatures
Ensure your plants thrive by timing planting with soil temperatures.
While early timing is important for the season up ahead, you don’t want to lose any tender plants to an unexpected late frost. The best way to time your planting is to use a soil thermometer in your garden beds. Ambient weather temperatures can be less reliable because they change drastically overnight. On the other hand, soil temperatures shift slowly. They are more reliable indicators that the weather is actually settled and your plant roots can thrive.
Put the probe at least 6-8” deep in the soil and check that it is consistently above 50°F (10°C) before planting tomatoes, peppers, and eggplant. Wait until temps are over 60°F (16°C) for crops like sweet potatoes, cucumbers, squash, and melons. The latter plants are often more suited to direct sowing unless you are transplanting them in soil blocks or biodegradable pots.
Hardening Off
Ensure seedling success by properly hardening off before transplanting.
Once you are certain that the soil is sufficiently warm, remember to harden off your seedlings. If you purchase seedlings from a nursery, they are likely already hardened off. But if you grew your own, it’s important to provide a transition period for the baby plants to adjust to outdoor temperatures while they’re still in their pots.
Bring them outside to a protected area like a patio for a few days before planting. Bring them back indoors for the first few nights, and if they don’t show signs of stress (like yellow leaves or wilting), leave them outside at night. After a week of acclimation, it’s safe to put the plants in the ground while minimizing transplant shock.
Row Fabric
Shield your crops from spring’s fickleness with protective row covers.
As an organic farmer in northern New Hampshire and northern Montana, I know how finicky spring weather can be in northern zones. One day, it’s sunny and 70°F (21°C), and the next night, you may have an unexpected freeze. The best way to buffer against these extremes is to use low tunnels, row covers, or both.
Low tunnels are miniature greenhouses that hover just a few feet off the soil surface. You can bend aluminum pipes or PVC over the bed like hoops, then cover them with greenhouse plastic or row fabric. Row fabric is an agricultural textile that allows sunlight and water in, but increases the temperatures by up to 8 to 10°F (-12 to -11°C), depending on the thickness. You can also “float” the fabric directly over the top of newly transplanted seedlings and weigh down the edges with sandbags or smooth rocks.
Whichever option you choose, I highly recommend row fabric for every northern grower. The covers are affordable, reusable, and dramatically increase young crop success. Better yet, row cover physically excludes early-season pests, so your young crops remain resilient against pesky bugs like flea beetles and cucumber beetles that are hatching with the warm weather.
Direct Seed Root-Sensitive Crops
Embrace simplicity by direct seeding your summer garden favorites.
When summer weather finally arrives, you can enjoy the simplicity of direct seeding crops in the garden. Many plants actually perform better when their seeds are sown straight into the soil rather than transplanted. This is particularly important for members of the squash family (Cucurbits or Cucurbitaceae), including:
- Cucumbers
- Pumpkins
- Cantaloupe
- Watermelons
- Zucchini
- Winter Squash (butternut, delicata, acorn, etc.)
These plants absolutely despise root disturbance. Their taproots are very sensitive and prefer to be established in place. Direct seeding is ideal as long as the soil is warm enough and you can keep the seeds consistently moist while they germinate. I’ve found that directly sown cucumber plants often out-pace transplanted ones, even if the newly seeded plants are several weeks younger than the transplanted ones. Transplant shock can really set back your crops, so you can save a lot of time and money by waiting until the soil is warm and direct seeding.
As mentioned above, checking the soil temperature is critical before planting tender crops. Many cucurbit seeds won’t germinate in soils cooler than 60-70°F (16-21°C). The soil temperature can differ tremendously from the ambient (air) temperature, so use a thermometer probe instead of your weather app to determine the right time for seeding.
Plant Warm-Weather Flowers
Enrich your summer garden with a vibrant tapestry of blooms.
While daffodils wither on the tail end of spring, it’s time to ensure you have plenty of warm-weather annual flowers planted to provide rainbows of blooms throughout the summer. Cheerful marigolds, pest-deterring white alyssum, vibrant zinnias, lovely cosmos, gigantic sunflowers, and native wildflower blends are just a few of the warm-climate flowers that jump to life in May.
Whether starting from transplants or seeds, scatter these flowers throughout your ornamental beds and vegetable garden to attract pollinators, enhance pest control, and provide companion plant benefits to your crops. A diversity of blooms ensures you have continuous color, as well as a consistent supply of nectar for your local bees and butterflies.
This is also the time to plant or purchase your favorite hanging baskets of petunias, million bells, and calibrachoa to brighten entryways and patios. In southern gardens where the weather is already sweltering, consider annual flowers that will bloom all summer long, like lantana, blanket flower, ageratum, coleus, cornflower, gerbera daisies, nasturtium, pansies, and impatiens.
Check Your Irrigation and Water Wisely
Protect your garden from summer heat with efficient irrigation systems.
With summer heat and drought pressure increasing across many regions, irrigation and water conservation are of the utmost importance. If you haven’t already checked or installed your irrigation system, this May garden task can save your entire garden from dying when rainfall becomes scarce.
Overhead sprinklers are mostly out of style because they waste so much water and increase the risk of fungal diseases. As water droplets settle on the leaves of your plants, the excess moisture can attract pathogens and even scorch the leaves from sunburn. On the other hand, water-wise irrigation systems are designed to save as much water as possible while ensuring plants can uptake all the moisture they need to thrive.
Drip Irrigation
Opt for worry-free watering with efficient drip irrigation systems.
Drip irrigation has long been used in commercial organic farming and is now the most popular option amongst home gardeners. Whether you’re watering annual vegetables, perennial herbs, or ornamental shrubs, drip lines provide a passive, worry-free option that delivers water directly to the base of your plants.
Instead of watering from above, drip lines put the moisture right in the root zone where your plants can drink it up. Drip lines can also be buried underneath mulch to enhance their effectiveness and retain moisture through hot, dry months. This video includes everything you need to know about setting up a new drip system, even if you know nothing about irrigation:
Other Water-Saving Tips
Optimize watering efficiency with soaker hoses or Ollas irrigation.
Soaker hoses are another great option for long-season annual beds or perennials. Ollas (clay pot irrigation) are ideal for containers, grow bags, and small raised beds. They can reduce watering needs by up to 70%! Simply bury a Garden Oya Watering Pot, fill it with water, and allow the moisture to slowly wick through the clay walls into the surrounding soil. Your plant roots will receive only the moisture they need, which reduces the risk of overwatering or root rot.
If you have summer vacations planned, you may want to invest in an automated irrigation timer or at least a simple system that a neighbor can easily turn on or off from one location. Also, consider switching to drought-tolerant or xeriscape native ornamental plants that are adapted to your specific climate.
Get a Headstart on Weeding
Tackle weeding early to prevent summer garden headaches later on.
Catch ‘em small and save yourself a lot of headaches this summer! One of the most important May garden tasks is often the most dreaded— weeding. Fortunately, weeding is very easy when the weeds are still around the “bean thread” stage, meaning they are still young enough to kill easily. Bean thread stage weeds have small white spindly stems that you can easily knock out with a scuffle hoe or rake, allowing you to weed while standing up without the backbreaking work of yanking out a months-old goosefoot plant.
Weeding is a lot like doing the dishes; small but frequent action prevents an overwhelming mess later on. It’s easy to avoid this garden chore, but putting it off leads to an overgrowth of weeds that are much more difficult to control. If you weed your garden for just 5-10 minutes a few times per week, you can significantly cut back on weed pressure and keep your plants happy.
May weeding is particularly important because many summer crops are still getting established. Too much competition in the early stage of crop growth can dramatically reduce plant vigor and yields. By removing weeds at the smallest stage, you are ensuring that your favorite plants can grow to their fullest potential without feeling overcrowded by unwanted intruders.
Mulch Your Beds
Protect your crops and conserve water with spring mulching.
While discussing water-saving irrigation and weed prevention, we cannot skip over the importance of mulching! You can technically add mulch any time of year, but late spring mulching is particularly important because it ensures your crops are protected from unexpected temperature swings and summer droughts.
Chipped deciduous leaf mulch is my personal favorite because it creates a fluffy, dry, easily removable layer of protection around your plants. Simply lay out a two to four-inch thick layer on the soil surface and watch your crops flourish. The benefits of mulch include:
The mulch smothers newly germinated weed seeds, preventing them from sprouting up.
Mulch blocks UV rays from drying out the soil, which conserves moisture.
A well-mulched garden looks beautiful and clean.
As mulch breaks down, it boosts soil quality.
Mulch keeps your fruits and vegetables lifted off the soil surface so they don’t rot or fall victim to plant diseases.
If you didn’t save any raked leaves from last fall, or you already used them all, straw mulch is a perfectly fine alternative. Finer straw is ideal for vegetables like lettuce, tomatoes, and basil, while denser mulch works great for pumpkins, squash, and strawberries. Always be sure you have straw and not hay! Hay is filled with grass seeds that can quickly turn your garden into a weedy mess that chokes out your desired plants.
Also, check that your straw has not been treated with herbicides. Many grain and grass crops are sprayed before harvest to desiccate and kill the crop. This can wreak havoc on your garden, contaminate your soil, and kill all of your plants. If you’re wary of the straw bales available at the hardware store, your best bet is a premium straw mulch like GardenStraw that has been prepared specifically for gardeners. This straw is herbicide-free and finely shredded to make it easy to spread.
Be sure to keep mulch at least two to three inches away from the base of plant stems, as you don’t want too much moisture accumulating in this area. Mulch-smothering is a common reason for crown rot or stem rot.
Add Slow-Release Fertilizer
Nourish your plants for summer with slow-release organic fertilizer.
Prepare for summer’s prolific show by providing your plants with the nutrients they need to thrive. Compost-rich soil is often filled with all the nutrients and microorganisms that your crops need, but poorer soils with low amounts of organic matter typically need amending to ensure that plants have enough minerals to grow.
Slow-release organic fertilizer is the best option for gardeners because it provides a continuous supply of nutrients throughout the season. Products like feather meal, fish meal, bone meal, blood meal, manure, and all-purpose blends like Garden-Tone deliver biodegradable nutrients straight to the soil. These naturally sourced fertilizers boost microbial activity to fuel a healthy soil microbiome and create long-lasting fertility that will build up over time.
Adding a small amount of slow-release fertilizer to your beds at the time of planting can help young plants take off without risking fertilizer burn. May is also a great time to sprinkle slow-release nutrients around the base of perennial plants and trees to boost productivity throughout the summer.
Avoiding Quick-Release Fertilizers
Opt for slow-release fertilizers to prevent over-fertilization and nurture sustainability.
If you’ve had problems with over-fertilizing, it’s best to avoid quick-release plant nutrients. These synthetic fertilizers are made from petroleum-based byproducts that release a rapid flush of nutrients all at once. This can be problematic for young plants because the intensity of quick-release nitrates can cause fertilizer burn and other issues.
Moreover, synthetic fertilizers can harm the beneficial soil microbes that could be helping your plants. If you accidentally overapply these types of fertilizers, they can contaminate water sources and harm the environment. Slow-release fertilizers are the easiest, most eco-friendly option to ensure happy plants and long-lasting sustainability in your garden.
Prune Spring-Flowering Shrubs
Revitalize spring blooms with post-bloom pruning for healthier growth.
Many early spring blooms like forsythia, viburnum, lilac, and azalea begin fading by May. Pruning them after they finish flowering can help encourage a flush of new growth while maintaining the overall shape and health of the plant. Post-bloom pruning also promotes more blooms the following year.
Use sharp, sanitized pruners or loppers to cut back dead flowers, remove damaged branches, and shape the plant in your desired form. Unless the plant is severely diseased, overgrown, or damaged, avoid harsh trimming. Some herbaceous shrubs like azaleas, lavender, and rosemary can handle pruning down to about a foot off the ground, but this will set back next year’s growth. It’s best to chop off a maximum of one-third of a mature plant’s stems to ensure quick regeneration.
Do some research before you prune, though. Some perennials bloom on last year’s growth, and a heavy prune can reduce flowering for the season.
Deadhead Spent Flowers
Keep your garden blooming by deadheading spent flowers regularly.
Deadheading is not just for Grateful Dead fans! This process is essential for ensuring a continuous production of beautiful blooms throughout the summer. Deadheading means removing spent flowers by pinching or cutting them off of the plant. For most plants, this signals to them that it’s time to develop new blossoms rather than channel their energy into seed production.
In contrast, if you leave spent flowers on the plant, most species will work to produce seed heads. While some seed heads are attractive (like amaranth or hydrangeas), you can prolong the bloom cycle of your plants by deadheading.
The vast majority of garden flowers benefit from deadheading, but you should never deadhead vegetable flowers! The flowers of tomatoes, squash, peppers, eggplant, and cucumbers are essential to forming fruits— the edible portions of the plant that we love to eat.
Instead, prioritize deadheading ornamental blooms like geranium, blanket flower, larkspur, phlox, bee balm, and yarrow. These plants will reward you with more flushes of pretty blossoms. Some plants like astilbe and impatiens are considered “self-cleaning,” meaning they take care of withered flowers on their own.
Stake or Trellis Tall Plants
Secure your plants’ growth with early trellising for optimal support.
It’s important to install stakes and trellises before your plants get too large or woody. Newly transplanted tomatoes, pole beans, cucumbers, and nasturtiums all benefit from early trellising. Similarly, young fruit trees and espaliers need to be “trained” and trellised very early in their growth stage. While installing a trellis at the time of planting is ideal, you still have time in May to train the plants without damage.
There are dozens of styles of trellises you can install, from elaborate pergolas to budget-friendly fencepost trellises. Lightweight plants like sweetpeas and pole beans can get by with a simple netting, but heavier plants like tomatoes and even melons require a hearty, robust trellis. Perennials like hardy kiwi and wisteria need particularly strong trellises to last for decades of climbing growth.
When installing a trellis, take care not to pound stakes too close to the plant’s root zone. As you train vines upward, try not to bend them too harshly in one direction, or they may snap. It helps to use lightweight ties or clips to orient the vines in the direction you’d like them to go. Younger, greener growth is easier to train because the stems are pliable. Once plants become woody, a lot of patience is required to shift their growth.
Prune Away Suckers and Runners
Boost your garden’s yield by removing pesky plant suckers.
Plants like indeterminate tomatoes, strawberries, and cucumbers produce loads of suckers. Also called runners, these elongated stems are used by vining plants to rapidly spread across an area. While this can be advantageous in the wild, it is not so great for our garden yields.
Runners were nicknamed “suckers” because they literally suck the nutrients and energy away from the plant. Leaving suckers in place may result in a tangled mess of strawberry plants with very few fruits or an overgrown tomato patch with tons of foliage and few tomatoes. If you want your plants to focus on prolific fruit production, removing suckers ensures that the energy is funneled in the right direction.
Start by examining the plants in your garden and determining which ones produce suckers. You will most commonly see suckers emerging as new growth tips between the “elbow ditches” of a plant. This is where the main stem or vine branches off, and a new vine tries to grow at the intersection with the main stem. You don’t have to remove all of them, but removing a few has advantages.
Vining Vegetables
Maximize fruit yields with a “double-leader” system for tomatoes and cucumbers.
As an organic farmer, I always chose a “double-leader” system for my indeterminate (vining) tomatoes. This means I’d choose two main vines from the central stalk and prune away all other suckers. These two vines would grow upward on my trellis and produce loads of fruit rather than splaying all over the place with tons of lateral vines.
I used the same method for cucumbers to keep fruit yields at their highest. Some growers remove the runners and suckers of different species of squash, melons, and pumpkins. Check your seed packet for variety-specific advice.
Strawberries
Keep your strawberry patch tidy and productive by removing runners.
Strawberries are a bit different but follow the same general rules. Removing strawberry runners ensures that your patch stays tidy, productive, and easy to harvest. Strawberries produce outrageous amounts of suckers in their attempt to spread as ground cover. Unfortunately, this means less berries.
The runners look like long stems from a mother plant with baby leaves at the end. If left in place, each runner will root to form an entirely new plant. It will use the runner stem like an umbilical cord to suck nutrients away from the mother plant. To maximize your sweet berry yields, cut or snap off strawberry suckers at least once per week.
Mow Your Lawn or Prepare for a Lawn Alternative
Swap finicky turfgrass for low-maintenance ground covers for a lush lawn.
May mowing sets the stage for a verdant lawn throughout the summer. But if you’re tired of maintaining finicky turfgrass, this is also the time to put in a lawn alternative. Drought-tolerant ground covers like microclover, creeping thyme, and blue star creeper are increasingly popular alternatives to conventional lawns. These plants stay low to the ground and don’t require nearly as much water, fertilizer, or maintenance as grass.
Depending on the species, installing a lawn alternative usually requires smothering or ripping up the existing grass sod. You can do this with a tarp, shovel, or by hand. Purchase ground cover seeds from a reputable source and scatter them densely across the lawn. Rake into place and keep consistently moist until germination. While your yard may be a little patchy at first, it should be filled in by the end of summer and remain bright green while neighboring grass lawns dwindle in the heat.
Prevent Bolting
Regular pinching and harvesting prevent cool-season crops from bolting.
This final preventative garden task for May will lengthen the harvest window of your favorite cool-season crops. In mild climates, spring plants like lettuce, spinach, and cilantro benefit from pinching and harvesting to prevent them from bolting. When the days lengthen and warm, many cool-weather plants naturally try to “bolt,” or go to seed. They send up a long, tall flowering stalk that detracts energy from the leaf production. The plants can quickly turn bitter and unappetizing, effectively ending their harvestable window.
Pinching, pruning, and regular harvesting are keys to preventing bolting. You can also use shade cloth or companion planting (in the dappled shade of taller plants) to keep these plants in their productive stage. For example, I like to extend spring lettuce harvests by seeding lettuce six to eight inches from the base of trellised tomatoes. The lettuce enjoys afternoon shade from the tomato plants, which keeps it from bolting, ensuring I have an abundance of crisp leaves for summer salads and burgers.
Basil is another crop that easily bolts in early summer. You can prevent bolting by regularly pinching the leaf tips. Harvesting this herb ensures a continuous supply of fragrant leaves. But if you forget to harvest for a week, basil may start flowering. This is actually great for pollinators and beneficial insects, but you may wish to start another succession of basil to yield delectable pestos and large, flavorful leaves.
Final Thoughts
From transplanting and direct seeding to deadheading and pruning, the steps you take in May will ensure the best possible garden season ahead. Remember to check your irrigation system, remove weeds while they’re young, and mulch your beds to conserve water.
If you live in a northern area, keep your crops protected with row fabric just in case you are surprised by chilly nights. In southern zones, pull out your shade cloth and keep plants well-irrigated to protect them from harsh heat. Don’t forget to pinch, prune, and harvest regularly to prevent bolting.
