Can I Put Horse Manure in With My Potted Plants?

Raw Manure

• Raw horse manure is "hot," meaning that raw horse manure is too high in nitrogen to be applied directly to plants, as it can burn their roots and yellow their leaves. In a field, raw horse manure can be spread between rows where it eventually decomposes and soaks into the soil. But if placed in a container, it is likely to harm or kill your potted plants. Raw horse manure is also likely to attract flies and emit odor, both of which are undesirable in potted plants placed on your deck or windowsill.

Composted Manure

• Composting horse manure reduces its bulk and hotness, rendering it suitable to be used as fertilizer in your potted houseplants or container garden. Composted manure attracts fewer flies and is less likely to smell than raw manure. If the manure is properly composted at a high temperature, most weed seeds in the manure will be killed off, according to the Washington State University Extension. If you can obtain quantities of raw manure free or cheaply, compost it yourself in a compost pile or bin. Mix it with dry material like shredded leaves or straw, and turn it frequently so that oxygen can help break it down faster. Alternatively, you can buy composted manure at most garden supply centers.

Manure Tea

• Watering your potted plants with manure tea adds the nutrient and fertilizer benefits of manure without the space requirements of storing raw or composted manure. Manure teas encourage strong root development and can help nourish your potted plants consistently across the growing season, when the nutrients of soil amendments may have run out. You can purchase manure tea bags, which can be set into a 5-gallon gardening bucket, covered, and set in the sun to steep, or make your own by placing raw or composted manure into a tied cloth rice bag or discarded pillowcase. Water your plants with the manure tea once a week or so.

Mulch

• A layer of mulch on top of your potted plant soil will help hold in moisture and slowly release nutrients as you water. Plants in containers need to be watered regularly, as their roots can dry out and get overheated in small pots subject to drying winds and sunlight. If you are using a soil-less potting medium or well-drained potting soil mix for your container grown plants, add a layer of compost mulch to the top to slow water loss, suggests the Texas A&M University Extension website.