What Substances Will Affect the Growth of a Lettuce Seed?

Soil Care

• The substances in the soil, both naturally occurring and added, greatly affect how lettuce seeds grow. According to the University of Illinois, foliage rot can become a problem in wet or hot seasons, so it's vital to provide your seeds with a bed of good soil and proper drainage. Prepare the soil ahead of time by working the ground with a garden tiller to break up rocks and tightly compacted soils. Add 5 inches or more of compost or other organic matter such as manure. Good soil helps ensure that the seeds get a healthy start and grow properly.

Water Requirements

• North Carolina State University says lettuce has a high water requirement. However, how you water your crops can also affect seed germination and the growth of your crops. Start out watering your seeds lightly but often to prevent problems from occurring. This ensures that your crops get enough water over time, rather than large quantities all at once.

Chemcials in Weed Control Products

• Weeds reduce leaf crop yields by directly competing with crops for water, light and nutrients. It's vital that you control weeds, yet the chemicals in weed-control products may also affect the growth of lettuce seeds and other crops. Remove weeds manually before planting seeds and pull new weeds up from the root when they sprout after you've planted your lettuce seeds. Avoid using weed-control chemicals near plants, or use them sparingly, because you might end up killing your lettuce. Weed-control products contain harsh ingredients which are meant to kill weeds, but the toxins may also destroy beneficial plants and insects. Try natural weed-control products that don't harm plants.

Chemicals in Pest Control Products

• Chemicals in pest-control products can also affect the growth of lettuce seeds and other plants. The University of California, Davis recommends using Neem oil and natural pest-control products, since many chemical-based pesticides kill beneficial bugs along with the bad insects. Ladybugs protect plants by eating aphids and other pests that harm lettuce, but ladybugs won't eat the plants, so use chemicals sparingly to avoid killing the good bugs.