The Missouri Department of Natural Resources describes a Landscaping business as:

A business that will change the natural features of a piece of property by adding lawns, trees, shrubs, ornamental plantings, fencing, sidewalks or other structures and materials used in modern landscape architecture. A landscaping business can also sell supplies to improve properties such as soil, gravel, potting mix, mulch, sand, railway ties, blocks and other items.

You may need some or all of the following permits for a Landscaping business:

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Hazardous Waste Research, Development and Demonstration Permit

If your business owns or operates a hazardous waste treatment facility and wants to use new and experimental treatment technologies that do not fall under current regulation standards, you may apply for a Hazardous Waste Research, Development and Demonstration Permit.
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Open Burning Notification

Open burning is the burning of any materials in which air contaminants are emitted directly into the air without first passing through a stack or chimney. The Missouri Department of Natural Resources does not issue permits for open burning. Prior to conducting any open burning, businesses and citizens should contact the city or county of jurisdiction for any local restrictions.

The department's Facts on Open Burning Under Missouri Regulations - PUB2047 fact sheet summarizes allowable and prohibited open burning under Missouri regulations. It does not include open burning restrictions that city or county governments may impose in addition to Missouri’s state regulations. 
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Public Drinking Water Construction Permit

If your business plans to construct a public water system that will supply drinking water to the public, you must obtain a Public Drinking Water Construction Permit. You must obtain this permit if you also plan to complete the following construction projects to the water system: waterline extensions, waterline replacements, drilling water supply well, construction a storage tank, adding a disinfection system, treatment changes, building a pump station or other improvements or modifications. A public water system has at least 15 service connections or serves at least 25 people at least 60 days out of the year. If your business plans to connect to a permitted public water system, then you are not required to obtain this permit.
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Public Drinking Water Permit to Dispense

If your business plans to operate a public water system that supplies drinking water to the public, you must obtain a Public Drinking Water Permit to Dispense. A public water system has at least 15 service connections or serves at least 25 people at least 60 days out of the year. If your business plans to connect to a permitted public water system, then you are not required to obtain this permit.