Things to do in your garden in April.
Taken from the Ontario Master Gardener Calendar
by John Hethrington, Master Gardener Emeritus
Past President, Master Gardeners of Ontario
Please contact John for more information!
March Garden Tips: There are lots more things to do in your garden in April!
- Make sure you’ve done everything you were supposed to do on the March 2025 Master Gardener's List, or ask for a new copy. See email above. Spring had started to arrive by mid March and the snow then melted away quickly, but then there was the ice storm to close out the month. Wiarton Willy, who forecast an early spring, was wrong again! He’s only right 26% of the time!
- Start off the new gardening season with a few bend and stretch exercises every time before you start in the garden. I find skiing muscles have nothing to do with gardening muscles. Take it easy. There are a lot of gardening days before the next ski season.
- If you can find them, buy and plant frost-resistant pansies early in the month for spring colour.
- A New Program for Spreading Triple-19 Fertilizer: I have learned from the Guelph- educated agronomist at Mid-West Co-Op in Markdale that you should NOT spread 19-19-19 general purpose fertilizer over the snow on all your flower beds and shrub boarders, as I used to recommend. You will lose the Nitrogen as it will melt away. So, after the snow has gone, and new leaves have not yet appeared on your plants, you should spread it just in your flower beds. Triple-19 fertilizer is available now at the Mid-West Co-Op just south of Markdale on HWY 10 @ $34.20 a bag. With the tariffs, this price may change.
- Organize your compost pile for the new season. Start a new one with the top foot or so of compost material from last year’s pile as a base. Take the top off down to the new compost you have created and start a new pile with the stuff from the top 12 to 24 inches of the old pile.
- As the weather warms and the ground dries, prune back perennials and ornamental grasses to 1” to 2” from the ground. Collect dead material, shred, if possible, and put it on your new pile.
- Push any plants that the frost has heaved out of the ground back into place.
- Prepare your garden beds for planting. Dig in compost, and/or manure, and/or other organic material around each perennial plant. Remove weeds that have come through from last fall. When you have cleaned up the beds, Add 3” to 4” of mulch to control weeds this summer. For mulch try 13/40 Landscape Supplies on Grey Rd 40 for a variety of mulches - 519-599 1340.
- Here’s an opportunity. Look over your garden to determine what plants are in the wrong place, or have grown too big and need dividing, or you hate them! Dig, Divide, Pot-up and Donate any extra perennials you have to the St. George’s Anglican Church Annual Plant Sale, Saturday, May 24, 2025, 8 AM to noon. When you donate 15 or more perennials, you will receive an Income Donation receipt for the value your plants sell for. Plant intake days are Wednesday May 21, 10 – 3 & 6 – 730pm, plus Thursday May 22, 10 until noon. To register as a donor and get a FREE “Plant Donor Kit”, with Plant and Donor labels, a waterproof Sharpie Pen and complete digging, potting and labelling instructions, email stg.plantsale@gmail.com
- Remove winter rose protection. For Hybrid Teas, prune back to 6” or 8”and apply dormant oil spray before the buds break.
- Apply dormant oil spray to shrubs like euonymus that may have suffered from scale last year. Do it before the buds break.
- Prepare your vegetable garden with a good digging. Dig in compost and manure. Mid-month, plant the seeds of cool-weather vegetables like peas, spinach, lettuce, onions and beets. Plant seeds of frost-resistant annuals like larkspur, sweet peas and calendulas.
- When you can’t see your footprints in the lawn, it’s dry enough to rake it vigorously to remove any thatch. Repair damage with weed-free topsoil. Add grass seed to bare spots & keep moist.
- Fertilize your lawn with slow-release high-nitrogen fertilizer (the first of the 3 numbers on the bag). Slow-release urea costs more, but it’s worth it, as it should last until the fall.
- Apply crabgrass pre-emergent herbicide to your lawn, if required.
- When spring finally arrives, plant new trees, shrubs, perennials and biennials in your garden. No need to wait until the end of May for perennials and shrubs, that’s for annuals. Up here, June 1st is the date to safely plant frost-tender annuals. With a late frost forecast, cover annuals with a bedsheet at night.
- Re-fill your pots and planters with compost. But first, put empty plastic bottles with tops on at the bottom of large pots. You will need less soil and they will be lighter and easier to move. Add slow-release plant food to the top 4 inches.
- Start mowing your lawn only as needed. Keep it long to crowd out any weeds.
- Save Saturday, May 24 for the St. George’s, Anglican Parish of the Blue Mountains, Giant Annual Plant Sale on the church grounds at 166 Russell St. in Clarksburg. They are projected to again have well over 1,000 high quality perennials and shrubs to choose from, at very reasonable and competitive prices, plus free gardening advice from the 599 Garden Club plant experts. Sale runs 8 AM to noon. Come early for best selection.
- And finally, if there are any students out there who are interested in garden work after school this spring, as well as during the summer months, please get in touch NOW. There are lots of well paid jobs available. Contact John Hethrington casacarolejohn@gmail.com
John Hethrington,
Master Gardener Emeritus,
Past President, Master Gardeners of Ontario
Beaver Valley Probus Club