Hay is harvested from alfalfa and grass fields. It is actually the third-largest farm crop in the country after corn and soybeans. Hay is used to feed cattle, horses, and smaller animals from goats to guinea pigs. It includes the nutritious leaves and seed heads of the plants.
Straw is the hollow and dried-out stems left over from harvesting small grain crops such as wheat and oats. It is used for livestock bedding and is often sold in the fall for decorations. If properly prepared, it can be used as a raised-bed garden soil.
Straw may have a few weed seeds and a few grains of oats or wheat, but hay is filled with seeds. As for your question, yes, a thin layer of mulch can keep the soil just damp enough that seeds may sprout. On the other hand, a thicker layer of mulch (up to three or four inches thick) can help prevent weed seeds from sprouting.
It is a good idea to cover a vegetable garden with mulch, as many vegetables grow better and produce more fruit when the soil moisture doesn’t fluctuate too wildly. Mulch also moderates temperature swings. If you live in an area where the soil develops a crust when it is dry, gas exchange with the atmosphere can also be inhibited, preventing the roots from getting enough oxygen. Mulch helps prevent moisture and temperature fluctuations and helps prevent the crust from forming.
Now that your garden is filled with weeds, what do you do? If the weeds are still small, just scratch over the soil with a hoe to rub out the weeds. Don’t try to uproot them and don’t try to dig deep into the soil around the vegetables or you might damage the roots of the vegetables. If the weeds are older and bigger, a hoe is still useful; just try to protect the vegetable roots. Hand-pulling around the vegetables may be best.
If the weeds are small, you might be able to smother them with several inches of mulch, a few layers of paper, or plastic. Larger weeds will just lift the mulch, paper, and plastic up and keep growing.
Chemicals, including homemade recipes, must be used with caution, as they can evaporate and harm the vegetables.
In the future, make sure you are getting straw and not hay. Hay may be cheaper and seem like a better deal, but it shouldn’t be used as a mulch. Even dried-out hay will have a slightly green color, while fresh hay is definitely green. Straw is always yellow to brown. They both are harvested and sold in round, square, large, or small bales.
