If you plan to grow winter vegetables such as broccoli, cabbage, silverbeet, garlic, English spinach, kale, lettuce, potatoes or peas in containers, it is essential to select the right potting mix before planting. Choosing the best potting mix for vegetables will help ensure a successful growing season.
As an avid veggie grower, I know using the right potting soil for vegetables makes a huge difference in plant health and yields, and the ability of plants to resist disease or insect attack. Veggies are hungry growers and need a potting mix that has long-release nutrients with a good soil structure.
Key Potting Mix Elements
Drainage and Water Retention
Different potting soils have varying drainage capabilities. Good drainage is essential because it allows your plant's roots to access oxygen while still having sufficient access to water. The best potting soil for vegetables should have excellent drainage while also being able to absorb water like a sponge and release it to the plants as needed. A combination of ingredients of different textures and particle sizes creates different size pore spaces in between those particles.
Aeration
Aeration closely relates to drainage. The pore spaces between the particles of potting soil determine how much air and water can move in and out of the mix, reaching the roots of your vegetable plants. When these pore spaces are not filled with water, they should be filled with air, as plants require equal access to both. The ability of a potting mix to provide proper aeration and water retention is crucial for speedy growth.
Nutrition
The ideal potting soil for vegetables should also provide ample nutrition as the plants grow. A good mix must include a slow-release nutrient source to feed your plants over time.
Support
Container-grown vegetable plants require potting soil that offers adequate support. The soil should hold the roots firmly in place to keep the plants upright. For root crops, it is essential that the soil supports healthy downward growth, preventing deformed or stunted roots.
Always buy premium potting mix with five ticks and six months controlled release feeding, wetting agent, water retention crystals, growth stimulants, trace elements, and coir peat. This will get your veggies off to a great start. Remember to liquid-fertilise with worm juice or kelp products every two to three weeks to encourage growth.
Old potting mix can be revamped by mixing in fresh compost, coir peat, wetting agent, manure, and kelp products, ideally throughout the mix, but if that is not possible, at least in the top 15 cm.
Tip of the Week
Soil will settle down in pots after a couple of months and may need topping up with a combination of 50:50 potting mix and a combination of compost and manure.
Three Jobs to Do Now
- Keep controlling powdery mildew on hydrangea plants by removing the worst-affected leaves and spraying with a liquid copper spray to prevent it from spreading to other hydrangeas.
- Prevent slugs from eating shasta daisy flowers by leaves by diluting one part fresh espresso to five parts water, and pouring over plants daily.
- Add flowers into pots filled with veggies — such as lobelia, violas and pansies — to attract pollinators.
Do you have a question for Sabrina? To submit a question to Green With Envy, inside Saturday's The West Australian, write to Ask Sabrina, GPO Box D162, Perth, 6001 or email home@wanews.com.au. Please include your full name and suburb. Due to the volume of questions, not all of them will be answered.
