top of page
lbsustainable

Essential Gardening Tips & Advice for the Month of May

Updated: May 21, 2024

In this months post, I will guide you through the essential gardening tasks, provide top horticultural tips and expert advice so you will know what to do and how to do it to bring out the best in your lawn and garden during this busy gardening month of May.


Shakespeare called it the "Merrie month of May" and its easy to see why with gardens overflowing with colorful blooms, fresh green growth, buzzing pollinators and cheerful bird song. This late spring month is truly a glorious one. The soil has warmed up and the days are long which contributes to vigorous growth of the lawns and gardens.


Pastel blooms of Wisteria dangle from pergolas and archways, the intensely fragrant blooms of Lilac fill the air as you walk by, Rhododendron and Azalea are at their flowering best, late-spring flowering street trees of Hawthorn, Crabapple and Horse Chestnut brighten up city streets and parks and lawns are lush and emerald green. Our native Pacific Dogwood is in bloom this month with its clusters of white flowers, that are actually four to six white leaves clustered around many tiny green flowers.


The late spring flowering Alliums are one of my favorite sights and add vibrant color and texture to any border. They pop up in my raised vegetable garden adding bursts of color when the early spring bulbs are finished and before I plant out my main crops of tomato and pepper plants.


This is my favorite time to visit botanical gardens such as VanDusen in Vancouver when the Laburnum walk is at its peak with meandering rows of yellow sweet pea like flowers hanging in dense clusters that are underplanted with vibrant complementary bright Purple Sensation Alliums. It's truly worth a visit to catch this and stroll along the magical walkway beneath the incredible hanging clusters of yellow. The Cornus kousa or Korean Dogwood with its clusters of vibrant pink flowers is also well worth the visit to see in bloom later this month and into June.


In my raised veggie garden, my Chervil herbs are growing vigorously and have been making a great addition to scrambled eggs and omelettes and my French Sorrel has never looked heathier and is ready for harvesting. The leaves can be harvested by cutting back to the base where new leaves will grow for more harvesting before the summer. I direct sowed annual Arugula and micro lettuce in early April into a section of the garden which are developing young plants that will be ready for harvest by mid May. When those spring crops are finished I will use the space to plant my young tomato and pepper plants I grew indoors from seed that have developed into healthy seedlings. They will be potted on indoors, hardened off gradually outside and then planted into their permanent position in the veggie garden in June.


When one vegetable is done there is a successional planting of the next seasonal vegetable or herb for a continual harvest and the space isn't wasted.


I sowed seeds of Calendula and Nasturtium along the front border of the raised veggie bed which are currently developing into seedlings. The make for excellent companion plants to many herbs and vegetables as they protect edible plants from predator insects and attract pollinators to the garden. They're also edible themselves, making a nice fresh addition to salads and the dried flowers can be used in herbal teas.


My over-wintered potted Oregano and Thyme were cut back in late March to rejuvenate the plants and the new growth is lush and ready for using now. My over-wintered container grown Rosemary is in flower and is looking really healthy.


I also sowed Arugula and mixed lettuce greens in containers in early April and have been fertilizing with diluted liquid Fish Fertilizer every 2 weeks and they are looking healthy and ready for harvesting now in early May.


There is much to do in the gardens this month with lawns to be regularly maintained, garden beds to be weeded, shrubs and perennials to be installed, hedges to be trimmed, tender annuals to be planted out later this month, vegetable seeds to be sowed and seedlings to be potted on and hardened off to prepare them for their final outdoor permanent planting at the very end of this month or in June. Please do read on for details of what to do and how to do it this busy gardening month of May.



Lawn & Garden Jobs for May:


  • Deadhead Daffodils and Tulips-Do not cut back the stem or any of the foliage as this will contribute to the growing bulbs as they slowly die back

  • Lift and divide overcrowded clumps of Daffodils and other spring flowering bulbs

  • Grasses are best divided once they have started to grow vigorously (unlike herbaceous perennials)

  • Lift the clump and divide into fairly substantial sections - they grow slowly so do not cut them up into very small pieces

  • Divide spring flowering perennials after they have bloomed such as Primulas and Pulmonarias

  • Cut back trailing rock plants such as Iberis and Aubretia after flowering to encourage bushier growth and prevent legginess

  • Stake and support herbacious perennials before they get to big and flop over

  • Plant out dahlia tubers and be sure to set the stakes in first to avoid damaging the tubers

  • Plant up Gladioli corms outdoors

  • After May long weekend and when nightime temperatures are reliably warmer, plant out tender annuals in beds, containers and window boxes and purchase hanging baskets

  • Prune early flowering Clematis-The best time to prune early-flowering clematis such as c. montana, armandii, alpina and macropetala, is immediately after they finish flowering

  • Tie in new growth of climbers to support structures

  • Deadhead faded Rhododendron flowerheads by gently twisting off spent flower seed-heads and being careful not to damage emerging new shoots at base of flowerheads

  • Mulch around shallow rooted shrubs such as Rhododendrons and Camellias with compost to help retain moisture going into summer, if not already done so

  • Sow biennials-sow wallflowers, honesty, foxgloves, forget-me-nots or sweet rocket for a lovely display next spring and summer

  • Keep garden beds and lawns well weeded. I prefer to hand-weed or use a weeding tool then to spray chemicals

  • Mow the lawn regularly on a weekly basis and take off no more then 1/3rd of blade height at each mowing. Set the blades at 2 1/2 to 3 inches.

    • Regular weekly mowing allows you to keep pace with the cutting so you aren't taking off too much new growth at once

    • Sharpen blades as they develop nicks or begin to feel dull. Grass ends look frayed and get a white sheen on their edges when blades are too dull

    • See April blog post for best lawn care practices

  • Fertilize lawns in May when grass tips are actively growing

    • I like to use an organic slow release spring lawn fertilizer in the nutrient range of 16-2-3 or 14-4-8.

  • Continue preparing new lawns and improving lawns (see April post for detailed instructions)

    • Avoid walking on or mowing newly sown grass until it has reached 2-3 inches tall. Even then, only give it a light trim, with the blade at the highest setting

  • Define the lawn edges using a half-moon edging iron or spade, creating a 7.5cm (3in) gutter around the lawn. This will prevent grass creeping from the lawn into your borders

  • Trim evergreen hedges such as Yew and Boxwood

  • Prune spring flowering shrubs after flowering

  • Pot on plants showing signs of being root bound

  • Liquid feed plants in containers every two to four weeks-I like to use a seaweed fertilizer which is a good general purpose feed

  • Bring out over-wintered Citrus fruit mid-month onwards

    • This is also a good time to prune them, cutting back damaged, scraggly or untidy branches.

    • Oranges and lemons are forgiving of hard pruning and need reinvigorating so remove a few of the oldest stems each year to be replaced by new growth

  • Flip the compost or if you have a large amount of compost at least flip the top couple feet and aerate with a garden fork every 2 weeks


Fruit and Vegetable Garden Jobs for May:


  • Continue successional direct outdoor sowing of lettuce, spinach, carrots, beetroot, peas and radishes

  • Sow indoors squash, pumpkins and cucumber mid month onwards

  • Plant late summer/early fall harvest potatoes from late April through to end of May

  • Earth up potatoes in the vegetable plot as well as for those grown in containers or grow bags to ensure newly formed potatoes aren't exposed to light which renders them green and inedible

    • For garden plot grown potatoes earth up with compost or garden mix soil when the foliage has grown approx 9 inches tall

    • For container grown potatoes hill up when the foliage has grown approx 12" above the soil. Add another 6" of soil around the base of the plant with covering some of the foliage as well, which is fine to do

  • Feed tomato plants with a well balanced liquid fertilize such as Liquid Seaweed or Fish Fertilizer diluted with water in a watering can

  • Prick out and pot on plug or seed tray grown tomatoes and peppers into 3" pots and using a potting compost. The upgrade in nutrition from seed compost to potting compost or all purpose compost is beneficial at this stage of growth

  • Harden off tender young plants that have been grown from seed in a windowsill or greenhouse by gradually introducing them outside for a few hours each day and working up to a full day after 5 days or so. Do this mid to late May

    • Place them in a sheltered position outside and bring them in at night. After 1-2 weeks they should be prepared to be transplanted permanently outside and exposed to direct sunlight

  • Take propagation cuttings of Rosemary, Sage and Thyme this month

  • Keep vegetable garden well weeded and keep an eye out for pest such as aphids, caterpillars and slugs

  • Open greenhouse vents and doors on warm days to keep well ventilated

  • Tie in Raspberry canes at they grow and develop to support structure using soft ties or twine

  • Remove new Raspberry growth growing outside the support structure as it will shade out the fruit-bearing canes.

    • These can be transplanted to areas where more canes are needed or simply removed



Lindsay's Top Tips for May:


Lawn Care:

  • Consider mulch mowing if you have a mower with a mulching setting as grass clippings cycles beneficial nitrogen and organic matter back into the lawn

    • Do on dry or relatively dry days and when grass hasn't grown too long between cuttings

    • Where weed pressure is high in lawns or weeds have gone to seed, its best to bag clippings to prevent the spread of weed seeds throughout the lawn

  • During hot dry stretches of weather, keep your lawn a little longer then usual and mow on a 3" setting to prevent evaporation and drying out

  • If moss is a problem, aerating and applying Lime in late Feb through to early May can help improve the conditions for better grass growth and reduce moss.

    • As the weather gets warmer and drier, rake up moss using a spring-tined rake. If that isn’t successful, there are fertilizer products with moss control in the form of Iron that can be applied to lawns as well

  •  Fertilize lawns in May when grass tips are actively growing

    • In winter and early spring, grass is putting its energy into root establishment/growth which is important for its ability to cope with drought conditions

    • The more established and deeper the roots, the better it can handle drought and require less watering

    • I like to use an organic slow release spring lawn fertilizer in the nutrient range of 16-2-3 or 14-4-8. If you cant get your hands on a fully organic product, then slow release nitrogen is the next best thing

Growing Vegetables:

  • When starting seeds indoors use a sterile seed starter mix which is low in nutrients but provides an ideal medium for seeds to germinate in

  • As seeds germinate and develop into young seedling plants, I begin a biweekly feed of a diluted liquid seaweed before potting on into a slightly roomier 3 inch pot using a potting compost containing more nutrition. The nutrients in compost provides the plant with adequate nutrition for a few weeks but after 2-3 weeks after potting on, I resume fertilizing on a weekly basis.

  • When fertilizing seedlings such as tomatoes and peppers I grew indoors from seed, I like to use a liquid seaweed fertilizer in the range of 1-2-5 applied on a weekly or biweekly basis. Fish fertilizer works well also in the range of 5-1-1 or 5-2-2. Don't use feeds too high in nitrogen at this stage. Liquid feeds diluted in water work better then granular fertilizers at this stage in their growth.

    • When its time for being transplanted outdoors into containers or vegetable beds, I use Bone Meal applied to the planting hole which is rich in phosphorus that is beneficial at this stage for root establishment

    • Ill discuss fertilizer requirements at each stage of the growing process in subsequent monthly posts.

  • When potting on seedlings grown in seed trays or plugs into slightly larger 3-4" pots, avoid lifting up the seedlings by the stem as they will not recover from damaged stems. The true leaves are important to their development too so its best to gently push from the bottom if in plugs or lift out of a seed tray holding onto a seed leaf which is the first set of leaves to emerge as the seed germinates. The seed leaves are not essential to the plants development if damaged.

45 views0 comments

Recent Posts

See All

Comments


bottom of page