Starting seeds indoors in Kingston, Ontario, Bill Stevenson, REALTOR®, Century 21 Lanthorn Real Estate Ltd., Brokerage

Starting Seeds Indoors in Kingston

Should I start seeds when snowbanks are still high across Kingston and the area? Lawns are buried, and the ground is frozen solid. It does not look remotely like planting season.

But this is when the season actually starts, giving you a chance to build gardening skills.

When you garden in Eastern Ontario, the calendar matters more than the weather outside your window. From today to May 20, the traditional Victoria Day planting window, we are roughly 13.5 weeks out.

That date is not random. It reflects our frost history. Tender vegetables and annual flowers should generally not go outdoors before then. Some years, you get lucky, while some years you do not. Frost in early to mid-May is not unusual here.

Mid-February is about timing.

Everything begins with counting backwards.

The Frost Math

Use May 20 as your outdoor planting date. Then count back.

Hot peppers need eight to ten weeks indoors. They germinate slowly and grow slowly in cool light. That puts you into mid to late February. Starting them now is not early. It lines up with our climate.

Sweet peppers and tomatoes usually need six to eight weeks. In Kingston, that generally means mid to late March. Starting tomatoes in February and April becomes a battle with tall, thin plants reaching for light.

Cucumbers and squash grow quickly and dislike being root-bound. They only need three to four weeks indoors. Early May is usually fine for those.

Flowers follow the same pattern: marigolds, zinnias, petunias, basil. Four to six weeks before May 20 works well.

Count backward from your last frost date, and the schedule takes care of itself.

Understanding Zone 5 in Kingston

Kingston sits in Canadian Plant Hardiness Zone 5.

That matters when ordering seeds online.

Many seed companies list recommended growing zones and days to maturity. A variety that performs well in Zone 7 or 8 may struggle here because our growing season is shorter and spring soil warms slowly.

Zone 5 generally means:

  • A real winter
  • Late spring frost risk
  • Outdoor planting is often delayed until late May
  • A growing season that typically runs from late May through September

When browsing seed catalogues, pay attention to maturity days. A tomato that takes 90 to 100 days to mature fits comfortably. A 120-day variety may not finish before cooler fall temperatures arrive.

Knowing your zone prevents disappointment.

What Happens If You Rush

Every spring brings a stretch of mild weather. The sun feels warm. Snow recedes. The top layer of soil softens.

Then a cold front arrives.

Air temperature can drop below zero for a few hours. That is enough to damage or kill tender plants.

Cold soil also slows root growth, even if daytime highs look acceptable. Plants sit instead of establishing.

Starting indoors now removes the risk of damage from unpredictable spring cold snaps, helping you feel more in control of your garden’s success.

A Practical Indoor Setup

Elaborate equipment is not required.

Anything with drainage holes works. Old cell packs. Yogurt containers with holes poked in the bottom. A shallow tray with seeds spaced apart.

DIY seed starting indoors using a simple container in Kingston, Ontario, Bill Stevenson, REALTOR®, Century 21 Lanthorn Real Estate Ltd., Brokerage
Seedlings growing indoors using a simple container setup during late winter in Kingston.

 

Seed starting mix drains well and stays light. Good-quality potting soil also works. Garden soil can be used in a pinch, though it compacts more and may hold moisture differently.

Plant two seeds per spot. Germination is never guaranteed. Thin the weaker seedling later.

Label everything. At two inches tall, tomatoes look like tomatoes.

Light matters more than people expect. Light in February and early March in Kingston is short and weak. A bright south-facing window helps. Simple LED grow lights produce sturdier plants and reduce stretching. They do not need to be commercial grade.

Water carefully. The surface can look dry while the lower soil remains damp. Check before watering. Overwatering is the most common indoor mistake.

If seedlings lean, increase light rather than water.

Seed starting potting mix for germination in Kingston, Ontario, Bill Stevenson, REALTOR®, Century 21 Lanthorn Real Estate Ltd., Brokerage
Seed starting mix designed for germination and early root development.

Why People Are Starting Seeds Again

There is a practical reason more households are doing this.

Groceries are expensive. Fresh peppers, tomatoes, greens, and herbs add up quickly through summer.

A packet of seeds costs a few dollars. A handful of store-bought vegetables often costs the same.

One healthy zucchini plant can produce steadily for weeks. Four tomato plants can feed you through much of July and August. Two or three pepper plants reduce the need for repeated purchases.

The point is not rhetoric. The numbers make the case.

You also gain freshness and control. You decide what goes into the soil and what stays out. Harvest happens minutes before dinner, not days after transport.

For many families in Kingston and the surrounding area, starting seeds indoors is practical.

Vegetables and Flowers Work Together

Vegetables feed you. Flowers support the system.

Marigolds and nasturtiums can help deter certain pests. Zinnias attract pollinators. Basil flowers draw beneficial insects that support the overall garden.

Flowers also create structure and colour once the planting season arrives. If you are preparing your home for a late May or early June listing, early-started annuals can quickly boost curb appeal.

For now, the focus is on the trays on the table.

Looking Beyond Standard Varieties

There is also renewed interest in older, heritage vegetable varieties. Many gardeners are moving beyond standard commercial hybrids and looking for open-pollinated strains that were common decades ago.

Carrots were originally purple, white, or yellow before orange became the dominant colour. Tomatoes once existed in dozens of regional strains adapted to specific climates. Beans, peas, and lettuce varieties were often selected for flavour rather than uniform shipping durability.

Growing from seed gives you access to those options.

One source of heritage and open-pollinated seed varieties is Revival Seeds, a Nova Scotia-based company focused on preserving older strains suited to Canadian growing conditions. Ordering from specialized suppliers can provide varieties that are not typically available on big-box retail racks.

For Kingston gardeners in Zone 5, selecting varieties adapted to shorter growing seasons can make a measurable difference in yield and success.

Vegetable and flower seed display rack in Kingston, Ontario, Bill Stevenson, REALTOR®, Century 21 Lanthorn Real Estate Ltd., Brokerage
Vegetable and flower seeds are now available in Kingston as the indoor starting season begins.

If This Is Your First Year

Keep it simple: Tomatoes, Peppers, Zucchini, Marigolds…

Choose a sunny location that receives at least six hours of direct light. Work compost into the soil before planting out. Avoid trying to grow fifteen varieties in your first season.

A small garden done well builds confidence. Expansion can come later.

Wait for Victoria Day. Do not let one warm April afternoon convince you that spring has arrived.

Hardening Off Matters

Before transplanting outdoors, seedlings need time to adjust, which helps you feel patient and proud of nurturing healthy plants.

Indoor plants grow in stable temperatures with no wind and filtered light. Direct sun and wind can shock them.

Place seedlings outside in a sheltered area for an hour or two. Bring them back inside. Increase that exposure gradually each day.

After seven to ten days, stems strengthen and leaves thicken. At that point, transplanting is far less stressful for the plant.

Skipping this step can undo weeks of careful timing.

Where to Get Supplies in Kingston

Seed trays, potting mix, grow lights, and basic tools are typically available at Walmart, RONA, Canadian Tire (still Canadian-owned), and local garden centres once seasonal inventory arrives.

Seed starting trays, potting mix, and soil test kits at Canadian Tire in Kingston, Ontario, Bill Stevenson, REALTOR®, Century 21 Lanthorn Real Estate Ltd., Brokerage
Seed trays, potting mix, and soil supplies are available locally in Kingston in late winter.

 

Specialty gear is not required. Consistency matters more than equipment. Locally, you can get organic seeds from The Kitchen Table Seed House, which is located on Wolfe Island. If you choose mail order for seeds you cannot find locally, great suppliers include the Ontario Seed Company and  Sheridan Nurseries 

Frequently Asked Questions

Why start seeds now when there is still snow on the ground?

Planting date is determined by frost risk, not snow cover. Slower crops, such as peppers, need time indoors before transplanting.

What happens if I start tomatoes too early?

They become leggy and weak and often require repotting before outdoor conditions are ready.

Is Victoria Day always a safe time to plant?

It is a strong guideline in Kingston, but always watch the forecast. Some gardeners wait until late May for added caution.

Do I need grow lights?

Not always, but supplemental light in February and March produces stronger, more compact seedlings.

Is gardening worth it financially?

For high-yield crops such as tomatoes, peppers, zucchini, and herbs, even a small number of plants can reduce summer grocery spending.

What is the most common mistake?

Overwatering indoors and planting outdoors too early.

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