Sick Seedlings

Starting seeds indoors is always fun, but sometimes it can be disheartening, especially for beginners when newly sprouted seeds begin to grow and then overnight the seed tray looks like a mini tornado swept through. Seedlings are left horizontal, dead and dying, and appear to have had their stems pinched right at the soil level.

What happened is a disease called Damping Off. It’s caused by any of a number of fungi that occur in all soils and tends to attack slow-growing or weak plants. As the name suggests, the disease prefers damp conditions, exactly what is required for growing seedlings. There used to be commercial fungicides designed specifically to control damping off but they are no longer available to home gardeners.  A few precautions, however, can reduce the likelihood of damping off. 

Use clean containers and a soill-free potting mix for starting seeds. Fill seed trays or pots right to the brim with the soil and avoid spreading seeds too densely. This allows for more air movement at the surface. A small fan blowing across seedlings can be helpful, but keep in mind this can rapidly dry out the soil.

If you start your seeds under a plastic cover, which is the usual way, remove the cover as soon as germination has taken place as fungal growth loves the high humidity under the cover. For the same reason don’t overwater and avoid watering from above as this ensures the soil surface remains damp and conducive to fungal growth.

Many untested suggestions such as sprinkling cinnamon on the soil surface have made the rounds online, and though cinnamon does have anti-fungal properties, the only hard evidence is on cinnamon oil, rather than the powder (which may not be pure cinnamon), so I’d save it for the hot chocolate and apple pie.

Starting Seeds

For seed starting, keep it clean and simple. When looking for a suitable medium, first, to clarify, there’s potting soil, and potting mix, and the terms are used interchangeably and not always accurately. Those brightly coloured plastic bags with bragging labels can be confusing. The difference is potting soil contains soil, often only a little, sometimes a lot. It’s more suitable for use outdoors. There are, however, mixes specifically formulated for seed starting.

Peat Moss

 Most products on the shelf are potting mixes, sometimes referred to as soil-free. They can contain any number of ingredients, with the usual claims for best results, but the ingredients aren’t always on the label. They can contain coco coir, wood fibers, peat moss, vermiculite, clay, pumice, or perlite. 

All have their uses, but not all are essential for starting seeds. Seedling grow best in a lightweight medium that provides a balance between moisture and air. Most potting mixes are made up of finely shredded peat moss. Perlite is usually added to improve drainage, and it also helps retain moisture. Perlite is a naturally occurring siliceous volcanic rock that after processing looks like tiny bits of popcorn.

Perlite

Cheaper, no-name brands might even contain tiny beads of polystyrene as a perlite substitute (in my darker moments, I’ve often thought potting mixes would be a handy way to dispose of industrial waste). Some mixes also contain vermiculite, a spongy, gold coloured volcanic mineral added to help retain moisture.

 

Vermiculite

Lime might be added to neutralize the slightly acidic peat moss, and other ingredients may include wetting agents to promote absorption of moisture, slow-release fertilizers, and charcoal, which is a natural filter that absorbs decaying plant odours. The problem with added fertilizer is you have no control over the amount, and since we all use our preferred fertilizers as well, there’s a danger of over-fertilizing. I prefer to be in control.

For seed starting, keep it clean and simple, and I'd avoid the $1.99 bags from that other store.