Here are some steps you can take when planting and growing your young vegetable plants to help prevent plant diseases.

Start with super clean pots. Be sure to clean all visible residue from previous use or use new containers.

Healthy seedlings and a healthy environment will result in healthy plants, and you will have a better chance of avoiding diseases.

Here are a few tips that will allow you to put the odds in your favor from the start:

1) Disinfect your containers.

Soak washed pots, plates, and trays in a solution of one part bleach to 10 parts water for half an hour. This will kill any remaining plant pathogenic microorganisms that may weaken or kill your tender young seedlings. It is also good to clean the trowels with the bleach solution.

2) Promote a good seedbed environment.

Sow seeds in weed- and disease-free starter and transplant mixes. A good planting medium should be fine and even, but well aerated, loose and free of pests, diseases and weed seeds. It must also be able to retain and move moisture through capillary action. Look for these stands at your local garden store.

3) Don’t use soil from your garden for seedlings.

Don’t use soil from your garden to plant seeds indoors. Your typical garden soil is often too dense, full of weed seeds, and unpasteurized, leading to seedling disease and death. And that soil often doesn’t drain as well as planting mixes. It can develop a scab that prevents seedlings from breaking through the soil.

4) Favor the soil.

Good soil will increase your seedlings’ chances of success.
A simple recipe for a good basic pasteurized potting soil for growing vegetable seedlings: mix one-third (by volume) pasteurized soil or compost, one-third sand, vermiculite, or perlite, and one-third peat moss. Other recipes abound on the internet, but this one is simple and straightforward and has worked for many master gardeners.

5) Pasteurize the compost.

To pasteurize compost, place slightly damp compost in a heatproof container or tray. Cover with a lid or aluminum foil. Place in a 250-degree oven for at least half an hour. Use a meat thermometer to make sure the mixture reaches a temperature of 180 degrees for a full half hour. Avoid overheating it as the soil structure can be damaged, making it useless as a soil ingredient for seedlings.

Cushioning

6) Follow the instructions.

Follow the recommended planting instructions on the seed packet. Whether you start seeds indoors or outdoors, follow the instructions on the seed packet according to your method. After planting seeds indoors, moisten the soil before sowing your seeds. Then, until germination, be careful not to wash off any loose seeds. I use a spray bottle to water the soil surface before the seeds germinate, then switch to irrigation from below as the seedlings develop a root system.

7) Maintain good air circulation.

Good air circulation is crucial once the seeds sprout and have multiple sets of leaves. Once the seeds develop true leaves, they need a lot of air. Not only does this discourage plant diseases, but the moving air also strengthens them. Be sure to remove any layers you may have had on the seed starting containers once the seeds have germinated.

8) Use heat from the ground.

A heat mat under the seedling pots will help the seeds germinate faster, preventing them from rotting. If you start planting cool-season seedlings like broccoli or onions, take them out and grow them in a sunny window or just under cool lights. Keep warm-season seedlings (e.g., peppers and eggplants) out of heat until they have several leaves.

9) Water wisely.

Once germination is complete, water from the bottom if you can. Try to keep the soil surface dry for as long as possible. Avoid frequent watering from above, as this keeps the topsoil too moist, which encourages fungal growth. If the seedlings are in cold floors or frames, give them as much air and light as possible. The drier the soil, the more light and better air drainage, the less chance there is of disease becoming a problem.

10) Don’t forget to fertilize.

Container-grown vegetables need regular fertilization. An all-purpose soluble fertilizer that can be mixed with water is the easiest type to use with potted plants. Fertilize every three to four days with a solution that is half the concentration of the recommended mixing ratio.

All of this horticultural hygiene prevents disease, including the deadly seedling disease called wilt. This fungal disease attacks young seedlings right after germination, when they are quite vulnerable. The stem of an infected seedling becomes discolored, begins to shrink, and then the seedling falls off.