May Garden to-do List

Spring's here and there's a lot to do in your garden as usual. Sharon Hanna breaks down the gardening tasks that you'll need to do for the various parts of your garden.

Credit: iStock

Here’s a list of tasks that you should be doing in your garden for May.


How is your compost doing? Decomposition should be well on its way, and soon the “bottom of the pile” will yield rich, black gold. Give yourself credit for keeping compostables out of the waste stream and the landfill while you’re at it.

You are creating a sustainable biosphere around your home by faithfully layering your veggie wastes with carbon (dried leaves, shredded newspaper), and a shovelful of soil. If you want to speed things up a bit, add some fresh horse manure or compost accelerator such as “Rot-It”.

Give all your plants, and especially veggies, a drink of compost tea. You can also use manure from a reputable source.

To make compost tea – fill a pair of pantyhose, porous old socks, or a heavy cheesecloth bag with well-rotted compost or manure. Hang in a bucket filled with water.  Let this steep for a couple of days; finished solution should be the colour of weak tea.  Dilute with water if necessary.

Children are particularly delighted if they’re allowed to dispense compost tea from an old slightly cracked teapot for this purpose – try to find one at a garage sale. There’ll be giggling galore, and the kids will be happy to water each and every plant in your garden with an afternoon “spot of tea.”


Closely monitor your greenhouse temperatures and air circulation. Temperatures can vary wildly from cold at night to boiling hot in mid-afternoon. You can purchase shade cloth to put on the roof, which cuts overheating substantially. Tomatoes don’t like to be too hot and get very thirsty as they are growing like crazy.

Begin bringing plants out of the greenhouse and slowly accustom them to direct light. Do this over a period of time, ideally at first giving them an hour of morning sun. They adapt quickly – no sunscreen required.


Towards the end of this month, when evening temperatures are warm enough for you to be outside with just a light cotton sweater (or a t-shirt!) it’s okay to plant basil.

When dealing with basil, it’s useful to remember that it’s native to South Africa and likes it hot and fairly dry. Always use fresh, new sterilized starter mix, seed lightly, and hardly water seedlings at all.

It is common for basil seedlings to die from being overwatered. Basil is susceptible to “damping off” – stems rot at soil level, plants collapse and cannot be revived. Knowing how much water is too much is an acquired skill.

Once basil has grown taller and stronger, it can tolerate more water, but never likes being overwatered, especially if weather cools.

If your garden is “sluggy”,, you might have better success if you transplant basil seedlings into pots rather than into the garden. Use a rich soil mix, or straight SeaSoil in the pots, and incorporate seedlings at  5-6 cm (2-3 in.)  

As basil grows, keep it picked. This encourages branching, and prevents flowering, then going to seed.

Here’s another way to grow lots of basil: fill a large plastic plant tray (without holes) to 3 cm (1.5 in.) from the top with soil (see above). Now add 2.5 cm (1 in.) of fine seed starter mix and pat lightly. Carefully sow basil seed, trying for even spacing. Do this when you’re feeling calm, and not rushed! Renee’s Seeds sells some varieties of basil seeds which have been coated with clay, making them very easy to handle! Great for this purpose… space seed about 2.5 cm (1 in.) apart in all directions. Lightly moisten with a spray bottle, set in a warm place in sun. If you put it in a greenhouse or indoors, be sure there is excellent air circulation. You’ll end up with a tray of basil which won’t grow gigantically tall, but it will be thick and bushy and you’ll have scads to use and enjoy.

Perennial herbs dislike being fertilized with any kind of chemical. They need very little feeding – a handful of SeaSoil, a dash of kelp is great. Fertilizers like 20-20-20 can kill young seedlings of herbs like thyme, rosemary, lavender, oregano, savory, marjoram – in short order. These herbs have evolved to struggle a bit – so let them. If you like, it’s okay to use very small amounts of well-rotted compost (it looks like soil) on them – but not too much. Save most of that for your veggies.


Veggie Planting Table

Start indoors or in the greenhouse: cucumbers, winter squash, melons (these don’t grow well on the coast!), all of these members of the Cucurbita family need to be transplanted out before the third “true” leaf matures – three to four weeks after planting indoors. This is important to keep in mind if temperatures are cool in your area.

In warmer areas, transplant outside: cabbage, cauliflower, artichokes, fennel, anything else you have growing inside.

Tomatoes – wait until at least the third week in May unless conditions are exceptionally warm. Tomatoes are set back if temperatures fall below 50° F (10° C).

Direct seed outdoors: broccoli, corn, parsley, turnips, arugula, carrots, cilantro, kale/collards, kohlrabi, scallions, spinach (bolt and heat-resistant varieties), Swiss chard, beets.  When (and only when) soil has warmed thoroughly – it feels warmish to your hand – direct sow bush/pole beans, zucchini/summer squash, and pumpkins.  This timetable applies to coastal areas – add two or three weeks more for cooler zones.


A healthy lawn is more resistant to problems including European chafer – a new and bothersome beetle, not to be confused with the beautiful shiny black beetle which eats slug eggs by the hundreds.White chafer grubs (the larval stage) are a favourite food of skunks and birds. Their digging to unearth their dinner results in a lawn that looks as though it’s been rototilled.

Even if chafers are not a problem, keep your lawn healthy by following these steps:

  • Water deeply once a week – 1″ is fine. This encourages long, deep root growth. Place a tuna or other can in the firing line of the sprinkler, and see how long it takes for 1″ to accumulate. Conserve water by aligning watering systems not to run off onto the street/sidewalk and into storm drains.
  • Avoid skimpy frequent waterings, daily sprinkling. This encourages shallow root growth resulting in unhealthy lawns. Water in the morning – evening water is wasted and creates dank, unhealthy conditions. It’s like going to bed with wet pajamas.
  • When you cut the grass, choose the highest setting on your mower, never less than 2″, preferably 3″. This creates a lush, thick carpet, shades the roots, keeps them healthy and cool, and discourages weed seeds from germinating. It also prevents chafer infestations.
  • Rather than raking grass clippings, leave them on top of the lawn. It’s a free source of nutrients, and helps retain water as well. They’ll disappear quickly.
  • Fertilize moderately, using environmentally-friendly slow or controlled-release products. Go easy – the more you fertilize, the faster your lawn will grow, and the more you’ll need to mow.
  • Use a push mower. Your neighbours (and the planet) will thank you, and, it’s good exercise. Second best is an electric mower; make gas-powered your final choice if you can.

Having said all that, why not allocate part of your lawn to grow food?

No need to build a raised bed – you don’t even have to remove the turf: try “lasagna” gardening – put down a thick layer (at least five sheets or more) of wetted newspaper in a sunny location away from trees. Cover with layers of dried leaves, straw, or other dry/carbon material. Cover with a thick layer of well-rotted compost, add soil. You can make the layers as deep as you want.  

Take a look at Carolyn Herriot’s blog for more information about lasagna gardening. 

Google “lasagna gardening” and you’ll find plenty of sites (over 100,000!), some with photos. Some sites advocate 30–45 cm (12–18 in.) in total of thickness. We’ve tried this at Queen Alexandra in our garden program and created 20–25 cm (8–10 in.) of height with good results – see below. 

Nature has been “lasagna gardening” forever. When you walk anywhere in natural settings, the ground is rarely bare.

Ruth Stout advocated a form of “lasagna gardening” before many of us were born; she felt it was common sense not to rototill or dig deeply. She let everything be, adding a bit extra on top every year, and digging only enough to incorporate her plants or seeds. Gardening in this way prevents more and more weed seeds from being exposed to the light when you bring them up from 15 cm (6 in.) down, and lets the billions of micro-organisms and other creatures work and live undisturbed. 

Once created, you can plant directly into your lasagna garden. Layers will slowly break down and you’ll keep adding layers every year – compost, SeaSoil, soil, manure – whatever. (If you have a good recipe for this kind of lasagna, we would love to hear about it!)

Transplants of tomatoes, squash, pumpkins and other veggies already on the go will be perfect for your lasagna garden this year.

At Queen Alexandra School, we first tried lasagna gardening in 2005 and it worked. The children stacked up leaves on top of the very hard gravel surface against a wire fence. We added a layer of hay from a haybale left over from Hallowe’en, a layer of our own compost, then a layer of soil from another area of the garden. We planted tomatoes immediately. We’ve had good results with zucchini one year, then leeks – also sweet peas and sunflowers.  

Continued on next page: Food Gardens, Flowers and Bulbs


See “lasagna gardening” (previous page) – grow some food this year even if it’s just a little. You’ll be glad you did. Homegrown food tastes very different from what you buy in stores and with little effort you’ll reap great rewards. Children love it and will eat things they wouldn’t normally eat if they’ve had a hand in the growing.

Start small and easy if you are new to food gardening. Grow a few things that you know you’ll eat – small-fruited tomatoes, zucchini, a few winter squash, some kale and lettuce, perhaps.

Day-neutral strawberries (those that flower and set fruit regardless of day length) are a good choice for gardens in the north, or shorter growing seasons. Because they don’t send off a profusion of runners, they are great in containers that can be overwintered.

Having said that, the larger-fruited, possibly more ephemeral June-bearing strawberries (to me) taste more luxurious. Why not grow a few of each variety?

Whatever kind of strawberries you are growing, feed them compost tea as often as you can remember. Keep them mulched well especially when flowers begin to form – it’s important that soil be evenly moist.

If this is all too much, grow wild strawberries instead. They have few demands, taste delicious, and are available in nursery centres about now in white and red varieties. They often seed themselves, and tolerate shade.

Raspberries should be mulched now, especially in warmer zones. Roots are shallow so keep digging and cultivating to a minimum. Too much manure or compost can cause an excess of leafy growth – do not overfeed.

Blueberries may be mulched with shredded bark or other slightly acid mulch. If you have any tree work done by professionals, they’re usually happy to chip tree materials for you.

Do avoid using cedar for mulching plants – it contains a growth inhibitor. It’s fine, though, for paths around your garden. Fir is suitable, as are chippings of deciduous trees, for mulching plants.


Direct-sow hardy annuals at the beginning of this month.

Thin out annual seedlings you planted previously. If handled carefully, you may be able to replant some, or pot them up to give away. Do this in cloudy weather, or in the evening so the little plants won’t be shocked. Tuck them in, and water gently.

Plant patio containers. Giant-sized containers don’t need to be filled with soil; most flowers only require 15–20 cm (6–8 in.) of soil at the most. Fill the bottom with dried leaves, wadded newspapers, lightly crushed empty pop cans – anything that will fill the space. An upside-down 3 or 5-gallon plastic pot will take up lots of room.  

Prune back spring-flowering perennials.  Pruning encourages vigour; plants may bloom a second time. 

Remove spent flowers of tulips, daffodils, other bulbs, but be sure to leave the foliage untouched and do not tie in knots. This season’s dieback creates bulbs for next year’s growth.

Place ring supports over peonies before they have grown too much – it may be too late depending on your zone and how the weather has been. Stems are brittle and snap easily with the weight of the beautiful, blousy fragrant flowers…

When hard frost is a thing of the past, plant out summer-blooming lilies and dahlias – if you haven’t already – adding a handful of bonemeal or bulb food if you are so inclined. “Eyes” (sprouts) of dahlias should be located on top. When planting summer bulbs, ensure water flows towards them by leaving a slight dip in the soil above the tuber.

Before adding soil it’s a good idea to push in a stake beside each tuber as a marker and sturdy support for the plant when it becomes taller. As foliage begins to grow up (similar to potatoes), backfill the hole somewhat, to not quite cover leaves.

Slugs love to nibble young dahlia leaves. Some folks report success using copper rings, copper wire, or copper tags in the soil around plants – it evidently gives the slugs a little “jolt” when their moist bodies come in contact with the copper, and they scram. Spent coffee grounds may also be effective here.

You might want to start dahlias earlier next season, in one-gallon black plastic pots, to get a head start. Particularly if you’re growing summer colours – pinks, reds, whites, bicolours – you might want your dahlias to bloom in July and August. Some people (me, for instance) prefer them later in fall hues of oranges, golds, and burnished reds.