Redwood Watering

Q. I have a group of establish redwood trees planted on a slope. I thought they were being watered by a natural spring but I’ve come to find out it was from a neighbor’s leaking water line that now has been repaired. Since then four trees have died. How do I go about saving the balance?

isolated redwood tree on a white backgroundA. Redwoods are not a drought tolerant tree like a pine, cedar, deodar and other conifers. They’re also shallow rooted and suffer from water stress with the hot afternoon sun beating on the soil. In their natural habitat, the needles catch moisture from the marine influence. The moisture then drips slowly down to cool and moisten the roots under the canopy of the trees. Hence they need to be irrigated frequently once the rainy season concludes. Stand alone trees, those with no vegetation growing under them, often struggle while those planted in a vegetative ground cover thrive. Established trees on drip irrigation suffer more than those watered by conventional sprinklers. The whole idea behind watering is to get the entire root system wet. The root system of a Redwood is found under the canopy of the tree. A common mistake made when watering Redwoods is that the volume of water is insufficient, infrequent and it’s not uniformly distributed around the tree. When using a drip system, there is a lack of understanding on how to make it work efficiently. First off, a drip system distributes water in a gallon per hour while a conventional system provides water in gallon per minute. A drip system needs to run forty-five minutes to an hour to provide the necessary volume to get the roots wet. In addition, you’ll need a dedicated water line for drip irrigation. A huge conflict develops when a drip system and conventional sprinklers share the same line. The volume of water plants receive is either too much or not enough. The second issue has to do with the number of emitters around the trees. The originally installed emitters need to be reposition every couple of years and additional emitters need to be added so water is available throughout the root zone of each tree. There is a misconception that if you puddle water in one spot, all the roots will benefit. The water absorbing roots are not located at the tree trunk but out toward the drip line of each tree. Redwoods produce a lot of natural litter or mulch to help with the moisture retention. It also insulates the roots from the hot sun, especially those trees where the lower branches have been removed. A two to three inch mulch layer under the canopy and beyond is recommended. It’s not necessary to mulch the base of the trees. In addition, your gardening service should be discouraged from removing this valuable covering. When the temperatures are over eighty degrees, I would be watering weekly. In summary, water and mulch are the keys to keeping your trees healthy.

Q. Can I be assured that the nutrients from a dry fertilizer will find its way to the roots when I water with drip irrigation or should I hand water the material into the soil?

A. With a granular fertilizer, I’d scatter the pellets within the drip irrigation distribution pattern and then hand water it in. After that, the drip system should do the rest of the job. If you were using a time-release fertilizer such as Osmocote, it would be absolutely critical. These products only release a tiny bit of nutrients with each watering. If you’re still not sure it s getting to the roots, I suggest you switch to liquid fertilizer.

Q. My Christmas Cacti are not very full and have gotten leggy. If possible, how would I go about taking a few cuttings and then planting them in the same pot to fill the bare spots?

A. This is a workable solution as cuttings can be taken and rooted off the existing Christmas or Zygocactus plant(s). The ideal time to take your cuttings is after they finish blooming. The cuttings should be about five inches long and broken off where the stem is segmented. Next, allow the cuttings to air dry for a day before starting the rooting process. The ends of the cuttings are dipped in a rooting hormone to help with the new root formation. You’ll find a rooting hormone at your favorite garden center. With a pencil or screwdriver, punch a hole in the existing soil and insert the cutting about a half and inch deep. (Although I prefer to root my cuttings in a separate container instead of the existing pots.) I’d take many more cuttings than I needed. The cuttings are then placed in a single pot of pre-moistened potting soil. The pot of cuttings is placed in an area with bright, indirect light and the soil kept moist. Once rooted, the most vigorous cuttings are selected and planted in the gaps or bare spots in each container. The rest of the cuttings are discarded or given away. Another option is to divide the mother plant and this is the perfect time to do so. Christmas Cactus are divided once every three to four years, depending on the pot size. Remove the plant(s) from the existing pot and divide the plant into sections using a sharp knife. Once segmented, decide which sections or the mother plant you like the best and discard the rest. You could also plant two sections in the same or larger container. When transplanting plants into a larger container, the general rule of thumb is to move them up one to two pot sizes; however with Christmas Cactus, I would only go up one size. They like to be pot- bound. They’ll skip a blooming cycle until the roots fill the soil area in the pot, if they are in too large a container. Finally, fertilize to encourage the new growth. While there are lots of right answers as to what to use, I prefer the time-release fertilizer Osmocote. A little bit of nutrients are released over a four month period.