What to do in the garden – June

Sharon Hanna breaks down the gardening tasks that you'll need to do for the various parts of your garden for the month of June.

Credit: iStock

Food gardens

Plant out tomatoes, zucchini and cucumber.

Cooler zone gardeners: place seedlings under a floating row cover to retain warmth and promote earlier fruit set. This can extend your growing season by as much as three weeks, especially useful for gardeners living in cooler locations. The cover also provides protection from direct sunlight until the seedlings get established. If the ground around the plant is bare, cover that too. The heat in the ground will help to insulate the plant against sudden temperature drops.

Covering carrot seedlings with floating row cover fabric also keeps out carrot rust fly whose larvae tunnel into the roots. Carrots like good, humusy soil of fine tilth and, like potatoes, dislike fresh manure or compost.

Plant tomatoes deeper than in the starter pot—past the two “seed” leaves, up to the next set of leaves. Or use the “trench” method—planting them almost horizontally, slightly downwards on one side. The more stem you can cover, the better. The tomato will right itself in an hour or so. Roots will sprout all along the stem for a healthier, sturdier plant that is well secured.

Always avoid watering tomato leaves—water the soil, not the plant.

Groom indeterminate tomatoes by pinching “suckers” regularly. If you allow suckers to grow, the plant will put its energy into making leaves instead of fruit. Good support—tomato cage or sturdy stake—makes a difference too. Re-useable green Velcro tape is handy for fixing tomato stalks to supports.

Keep tomatoes well watered (avoid wetting the leaves!) and fed. If they’re in the ground, compost tea, fish emulsion or kelp every two weeks or so is great while they’re in active growth. Tomatoes in containers require weekly feeding in order to have good results.

Every garden needs leeks—full of nutrition, yummy in soups and easy to grow. They can take a bit of shade, too, unlike most veggies, and their roots greatly improve soil tilth. In cooler zones, purchase transplants or try winter-hardy varieties like ‘Siegfried Frost’; on the coast, sow this month—most varieties will overwinter.

If mesclun and lettuce beds get stressed in afternoon heat, try shade cloth or even a big umbrella during the hottest part of the day.

If lettuce tastes bitter, water more frequently. Lettuce needs to grow quickly to taste sweet, and does so by never being allowed to dry out and occasional feeding.

If you haven’t started squash, pumpkins and cukes already, direct-sow by the first week of June. Be sure to make a curved indentation in the soil so water flows toward the seed and plant, especially if conditions are hot and dry.

Plant corn ASAP—in the first week of June if you haven’t already. Space-challenged gardeners can try the ancient Aztec “three sisters” method, seeding corn, squash and beans together. Corn needs to be about 10 inches tall before you plant beans for best results. Otherwise the beans will knock down the corn.

The nitrogen-fixing beans benefit the squash and corn, the corn holds up the beans, and big squash leaves shade the soil and keep it moist. Ancients buried a dead fish in each planting hole—the first “slow release” fertilizer? Try making “three sisters” soup—it’s delicious—many recipes to be had on the Net.

Keep strawberries happy by fertilizing them bi-weekly with fish emulsion and/or dissolvable kelp (a little of this goes a long way) If you’ve run out of sunny space, grow wild strawberries (Fragaria vesca) in shady spots in containers. They’re available in white and red types in garden centres this month. Renee’s Seeds sells ‘Mignonette’ strawberry seed—it takes about three weeks to germinate but grows into nice large plants in one season.

Pick nutrition-packed raspberries regularly—there’s a perfect time to pick them so keep your eyes peeled.  


Believe it or not, towards the end of this month it’s time to sow “starts” for some overwintering veggies like purple sprouting broccoli and big winter cabbage. Sow a few seeds per 4-inch (10-cm) pot in good loose starter mix. Protect from marauding slugs, grow on in dappled light, plugging into spots vacated by squash, tomatoes, beans etc. in early fall.  

Transplant out: eggplant, melon, peppers, tomatoes, squash, pumpkins, cucumbers.

Direct seed outdoors: Brussels sprouts, cucumbers, broccoli, corn, leeks; pumpkin, squash, bush and pole beans, beets, cabbage, carrots, lettuce, onions, parsnips, pumpkin, rutabagas, spinach, Swiss chard, turnips and winter veggies (on the coast, see above).


Water lawns once a week until a tuna can left in the vicinity of the sprinkler contains 1 inch (2.5 cm) of water (in the absence of rain, of course). Frequent shallow watering creates shallow roots that make for an unhealthy lawn. Set mower blades high—taller grass shades out weeds. Never water at night—this encourages disease.

If you’d like to remove part of your lawn and grow food there immediately, check out “lasagna gardening”—it’s not too late. Carolyn Herriot has information and photos on her blog.  It’s also on Oprah website.


Lightly prune shrubs after they finish flowering to clean them up. Prune any dead wood—it makes everything look so much better and can be done almost any time of the year.


Basil may be seeded outdoors now. (See What To Do—May for more about growing it.) There are so many types—Thai, cinnamon, lemon, large-leafed Genovese. If you have a lot of slugs, grow it in pots or purchase starts from the garden centre. You can never have too much basil! Don’t allow plants to flower and go to seed—keep the tops pinched off and toss into salads and onto your pasta. Or add wine vinegar and seal in jars to make basil vinegar.

Some gardeners swear that growing basil near their tomatoes helps both plants. It couldn’t hurt—basil is fairly shallow rooted. Do not let it get too dry (or too wet!).
Grow pots of chives, parsley, sage, thyme, rosemary and basil on the porch or stairs near your kitchen and you’ll use them more regularly. Often when you remember “a snip of this or that,” you’re draining the pasta so you don’t bother.


Protect new evergreen plantings by:
a)    Level planting—water runs IN to the planting hole;
b)    Mulching, mulching, mulching—with fir bark, cones, pebbles—just like the forest floor. Mulch maintains moisture, regulates soil temperature, deters weeds and releases nutrients over time. If bark is freshly chipped (tree services are often glad to aim the chipper at your yard), throw grass clippings on and/or add nitrogen fertilizer;
c)    Watering deeply and regularly. Avoid light sprinkling as this creates surface roots that are easily burned in hot weather.

Flowers, bulbs

First blooms of early-sown sweet peas appear soon —feed with fish emulsion and keep them picked so they don’t go to seed. Red-flowered varieties prefer some shade from the hot midday sun.

Continue planting annuals and water well.  Plant seeds between patio stones to out-compete weeds.  Try California poppy, Roman chamomile, creeping thyme and, in shadier spots, lobelia.

Delphinium can be difficult: prone to slug attack, weak and hard to coax back a second year. They’re also gorgeous and very rewarding to grow from seed! It’s easy – late June is perfect for sowing fresh seed (newly collected from a friend’s garden or yours). Use loose seed-starter mix and be patient as germination is variable. Transfer to 4-inch (10-cm) pots and overwinter in a cool greenhouse or porch. Plant in spring. Ensure protection from early slugs (try ringing plants with used coffee grounds). Give them good drainage and space.

Continue watering bulbs until yellowed leaves can be gently pulled off. The leaves will convert the sun’s energy into carbohydrate that will be stored in the bulb. This will increase bulb size and ensure good energy reserves for flowering next season.

Give roses a light feeding, as well as a handful of Epsom salts dissolved in water. If you’re frustrated with black spot or mediocre roses, try growing Rugosa types (wild roses). They’re disease-resistant, beautifully fragrant and simple to grow, though most have a shorter blooming period. “Pavement” roses are low growing and tolerant of many types of planting sites. Though not Rugosa types, “flower carpet” type roses are also sturdy, disease-resistant and easier to grow than their fancier cousins.

Propagation, seeds

Garden centres return seeds to seed companies in summer; be sure you have what you need for summer and fall sowing—arugula, salad greens, kale, any annuals you’d like to sow in October like bachelor’s buttons, California poppies, other “wild”-type flowers.

Easily sown in seed starter mix in 4-inch (10-cm) pots mid to late June: Aquilegia, Rudbeckia, Salvia, hollyhocks, Malva sp. Also, fragrant spring wallflowers (Erysimum sp.) started now will bloom next spring—great with tulips.

Zone 5–8: take cuttings of perennials: rosemary, lavender, Penstemon, lots more. Creative Propagation by Peter Thomas (Timber Press, reprinted 2005) is a fantastic resource featuring a very complete alphabetical list by botanical name with relevant dates for best results.


Continue to feed indoor houseplants while they’re growing. Regular spraying of non-fuzzy leaved plants will keep spider mites at bay. Houseplants that are enjoying camping out in your yard or porch for the summer should also be fed regularly. In cooler zones, you can gradually acclimatize houseplants to sun now (half an hour in the early mornings, gradually building up over a few days).

Around the Garden

Mulch to preserve moisture and keep weeds down. Use bark, rocks or chips for decorative, finished look. A layer of newspaper or landscape cloth underneath will stop weeds from growing through decorative mulch and will further enhance moisture retention.

Keep rhubarb mulched (using leaves, straw, hay or anything else) and watered—don’t let it dry out! It’ll keep producing that way.

Make compost tea using pantyhose. Stuff compost into legs (children love to do this), then soak the legs in a bucket of water for an hour at the most. Use this to water vegetables, raspberries, blueberries and other small fruit—just about everything will enjoy a drink of compost tea.

Keep hanging baskets moist. If the basket gets too dry, water sometimes runs out the sides and doesn’t get to the plants. If plants wilt and basket seems lightweight, dunk it in a huge plastic “muck bucket” filled with water and let it sit for an hour or two. Give it a drink of compost tea, too.  


Comfrey can be a nuisance once you have it. If you can’t beat it—compost it. Chop leaves and stems and add to your compost. Comfrey “mines” the soil for rich nutrients. Your compost will be super-powered.