To get an abundant and flavourful tomato harvest, it all starts with proper planting. Here are our tips for planting your seedlings in the ground or in pots, and making your gardening neighbours green with envy!
When to Plant Your Tomatoes?
In Quebec, located primarily in hardiness zones 3, 4, and 5, the key to successful planting lies in respecting the calendar.
- Zones 4 and 5: It is generally recommended to wait until late May or early June to transplant your tomatoes outdoors.
- Zone 3: In colder regions, it's better to wait until mid-June.
Why Is This Wait Crucial?
- Risk of frost: Even if days are warm, nights can still be cool, with temperatures close to freezing. Tomatoes, being native to tropical climates, are sensitive to frost and can be severely damaged, or even destroyed, by freezing temperatures.
- Soil still cool: The soil is not yet sufficiently warmed up and drained for tomato plants. Soil that is too cold and wet can delay growth, promote diseases, and harm the plants' survival.
Once all risk of frost has passed and the soil is sufficiently warm, choose a sunny location for your plants.
Where to Plant Tomatoes: Choosing the Right Location
Tomatoes are real sun-lovers. For optimal yield, offer them a spot where they will benefit from a minimum of 6 to 8 hours of direct sunlight per day. Ideally, choose a site that is sheltered from wind, which could break stems or dry out plants.
The Crucial Step of Hardening Off
Before transplanting your tomato seedlings grown indoors, it's essential to gradually acclimate them to outdoor conditions. This is called hardening off. Over a period of about 7 to 10 days before planned planting:
- Take your plants outside for a few hours each day, starting in a spot protected from direct sun and wind.
- Gradually increase the exposure time and sunlight each day.
- Bring the plants inside in the evening, especially if nighttime temperatures are cool.
This gentle transition will allow your plants to adapt to more intense UV rays, temperature variations, and wind, minimizing transplant shock.
In-Ground Planting: Preparing the Soil for an Abundant Harvest
Tomatoes thrive in soil that is rich in organic matter, light, and well-drained.
Soil Preparation: Before planting, work the soil by generously incorporating well-rotted compost or manure. This will improve soil structure and provide essential nutrients for vigorous plant growth. You can also add a biological all-purpose granular fertilizer at planting time.
Spacing: Dig holes large enough to accommodate the root ball. Leave 50 to 60 cm between each plant to ensure good air circulation, which is essential for preventing diseases. If planting in rows, allow about 80 cm between rows.
Planting Technique: Tomatoes have the unique ability to grow roots along their stem when buried. To encourage strong root development, remove the lower leaves and plant the seedling deeper than it was in its pot, ideally burying it up to half the stem. You can even lay a long, thin stem horizontally in a shallow trench.
Initial Watering: After planting, water generously at the base of each plant to settle the soil and eliminate air pockets.
Staking: Install a sturdy stake at least 1.5 metres tall at planting time to support plant growth, especially for indeterminate varieties which can become very tall and fruit-laden. Using sturdy tomato cages is also an excellent option. Remember to disinfect your stakes if you reuse them year after year to prevent disease spread.
Mulching: Once the plants are established, add a layer of organic mulch (like straw, shredded leaves, or compost) 5 to 10 cm thick around the base of the plants. Mulch helps retain soil moisture, reduce weeds, and maintain a more stable soil temperature.
Follow-up Watering: Aim for deep and regular watering at the base of the plants, avoiding wetting the foliage. This helps limit the risk of fungal diseases. Frequency will depend on the weather and soil type, but ensure the soil stays uniformly moist without being waterlogged. Lack or excess of water can cause problems like blossom end rot.
Companion Planting in the Garden
Certain plants can help your tomatoes grow better by repelling pests or improving soil health. Tomatoes get along well with:
- Vegetables: Carrots, celery, cucumbers, onion, garlic, peppers, asparagus, radishes.
- Herbs: Mint, basil, parsley, sage, thyme, rosemary. Basil is an excellent companion that is said to even improve tomato flavour and help repel certain insects.
- Flowers: Marigolds and nasturtiums can help repel certain nematodes and harmful insects.
Avoid planting tomatoes near cabbage, fennel, corn, beets, peas, and potatoes, as these associations can promote diseases or competition for nutrients.
Growing Tomatoes in Containers: Tomatoes Even in Small Spaces
Growing tomatoes in containers is an excellent solution for balconies, patios, or gardeners with limited in-ground space. Pots offer the advantage of soil that warms up faster and better protection against certain ground pests.
Choosing Varieties: For container growing, favour determinate (or bush) varieties. These compact, bushy plants reach a maximum height and produce their fruit over a shorter period. Dwarf or semi-determinate varieties are also good choices. Indeterminate (or vining) varieties, which continue to grow and produce throughout the season, require much larger containers and more substantial support.
Choosing a Container: A container with a minimum capacity of 20 litres is recommended for a determinate tomato plant, although a 30 to 40 litre pot is preferable for better results. For semi-determinate or more vigorous varieties, aim for 60 litres or more. Ensure the pot has drainage holes to prevent water accumulation. Dark-coloured pots retain more heat, which is beneficial for tomatoes. Self-watering containers can be useful, but make sure there isn't constant excess moisture. Smart Pots (geotextile fabric bags) promote excellent root aeration.
Pot Preparation: Wash and disinfect used pots. Fill the container with a mixture of quality potting mix, like Botanix potting mix for Flowers and Vegetables in Container and compost in equal proportions (about 50/50). Container-grown tomatoes have limited nutrient reserves, so enriched soil is essential.
Container Planting: Make a hole in the centre of the potting mix. You can add a small handful of 'special tomato' granular fertilizer or a slow-release fertilizer to the bottom of the hole, mixing it slightly with the soil. Position the tomato plant, removing lower leaves if necessary, and plant it deeper, burying a portion of the stem. Water generously after planting.
One Plant Per Pot: Plant only one tomato plant per container of the recommended size.
Watering Containers: Tomatoes in pots require more frequent watering than those in the ground, as the potting mix dries out faster. Water deeply as soon as the top of the potting mix feels dry to the touch, aiming for the base of the plant. In hot, dry weather, daily watering, or even twice a day during heat waves, may be necessary.
Staking in Containers: Install an appropriate stake or cage for the size of the variety grown at planting time to support the plant as it grows and bears the weight of the fruit.
Container Companions: To optimize space and potentially benefit from companion planting, you can plant a few herbs (basil, parsley) or marigolds at the base of the tomato plant in the same container.
By following these tips, whether planting in the ground or in a pot, you'll put all the chances on your side to get a generous and flavourful harvest of Quebec tomatoes! Happy gardening season!
