Garden docs: What's the difference between mulch and compost?

Joey asks: What is the difference between mulch and compost? I always assumed they were one in the same and both excellent additions when added to the soil.

You are pretty much right on. Compost is incorporated into the soil and it is adding a biologically active material that results in decomposition of organic matter. It improves the soil structure and creates and retains nutrients so the nutrients are readily available to plants. It can be mixed in existing garden soil to amend and improve the soil or spread on top and used as a mulch or top dressing.

This is where the confusion between mulch and compost sometimes occurs. Compost can be created in compost piles in the home garden or purchased for use.

Mulch is any material that can be organic or inorganic that is spread over garden soil to cover it for the purpose of suppressing weeds or keeping soil temperature cool and moist. Additionally, mulch helps to conserve water by preventing evaporation and controlling soil erosion. Organic mulch sold commercially is available in larger particles that take longer to break down, such as wood chips, leaves and grass clippings.

Hank writes: How frost/freeze sensitive are yucca and the plant that looks similar, Cordyline australis?

The sensitivity of both plants to frost and freezing temperatures depends on their origin. Are they from a tropical region, a desert or a cooler mountainous region? Knowing their correct botanical name will help you determine their sensitivity. Cordyline australis, according to my research, can safely thrive in temperatures down to 15 degrees.

Yucca glauca can survive to a minus 35 degrees. Yucca desmetiana, ‘Blue Boy', will survive with temperatures down to 20 degrees and probably lower than that with protection.

Frost protection material placed over the yucca or cordyline will help prevent damage. You may also create a frame of wood or sturdy wire that can go over the plant, Drape a sheet or blanket over the top for more freeze protection. A word of warning: While plastic sheeting placed over a frame is acceptable, never place the plastic directly on top of plants. This could permanently damage the plant.

Bette writes: I was given a small bat house for a present. Where is the best place to mount the bat house so it will attract bats? Should it be attached to a tree or can it be attached to the house or other pole?

Your bat house should be mounted 10 to 12 feet high on a site that is facing south to southeast. It should receive enough sun to keep the inside temperature between 85 and 100 degrees - in other words, very warm, because I doubt you are going to physically monitor the inside temperature. Bat houses mounted on tree trunks are susceptible to predators.

Mounting the bat house on the south side of a house can be a good spot as long it is not situated over a doorway or walkway where bat droppings/guano can develop into a messy problem. Guano appears as small black dots similar to the size of mouse droppings.

Bats are beneficial and feed on insects. According to Wildlife Animal Control, each bat can eat between 600 to 1,000 insects. They mostly eat flying night bugs like mosquitoes, moths and more. They have also been seen enjoying nectar from hummingbird feeders.

Ted asks: What is the recommended method of planting bare-root trees in hardpan soil. I live in a fairly new development and I have discovered it is almost impossible to dig deep enough and I want to do a better job planting a bare-root fruit tree in January.

For those readers not familiar with the term hardpan soil, here is a brief description: It is a soil that is under-laid by a rock-hard layer of material close to the soil surface that impedes the depth of the root development creating a maze of surface tree roots that would ordinarily be well below the soil surface. Hardpan is often created in new developments by constant compaction by heavy equipment as the home sites are developed. Impervious soils lead to waterlogged areas and severe drainage problems.

As newly planted trees mature, the lack of a deep soil structure, in addition to water logged soil that does not drain, prevents trees from developing strong, anchoring root systems. Such trees will be susceptible to high wind damage and blow over. This is frequently seen in street trees with their anchoring roots growing on top of the soil and lifting sidewalks.

To best plant your tree, dig a hole as deep as possible and fill it with water to check the drainage and the depth of hardpan. Check the water depth and if it has not drained significantly in 24 hours, rent an auger and use it to break through the underlying hardpan. Try and create enough holes so the water will drain and create fissures for new roots to break through the impervious hard sub-soil. Chinese pistache and oaks have deep taproots and have a difficult time breaking through hardpan and usually decline fairly fast. Both of these trees suffer in waterlogged soil.

Dana Lozano and Gwen Kilchherr are garden consultants. Send your gardening questions to The Garden Doctors at pdgardendoctor@gmail.com. The Garden Doctors answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.