Cut grass ringing lychee tree to encourage it to give fruit

Question: Why won’t my lychee tree fruit? We take good care of our lawn; it’s nice and green here in hot, sunny Salt Lake. We put fertilizer like they tell us at the store and have automatic irrigation. We bought a good grafted lychee about 10 years ago — but no fruit. Should we give up and chop it down? My uncle says to girdle it, but I don’t want to hurt it. It’s a really pretty, shady tree in the hot summer, and it reminds me of my popo. She always had tons of lychee in hot Makiki. — Mrs. K.L.

Answer: The winter we’ve been having with lots of rain and cool temperatures (freezing to us local folks) is the old-time kind of winter weather that lychee like. It’s like spring in China, where lychee are native.

Hotter, drier weather is one reason we don’t get as much lychee fruit as in the good old days. Older varieties of lychee also tend to fruit heavily every other year. New varieties such as kaimana are more reliable fruiters.

The biggest problem for your lychee (without actually seeing the tree and your yard) is that "nice green grass." Grass is competitive. It takes strength away from your tree.

Clear away the turf at least 12 inches from around the trunk of your lychee. Dig up the roots of the grass near the tree. At a microflora level, grass thrives with a bacterial-based soil, while trees thrive and are productive with a fungal-based soil.

Another reason to get rid of grass next to good trees is trimming damage to the trunks from mowers and Weed Eaters. Clearing a ring will make it easier and faster to mow, and you won’t put dings and scrapes on the tree trunk. Damaging the trunk and making puka and scrapes where they don’t belong is asking for trouble. Insects and disease can get into the trunk from the holes in the tree trunk.

Also do as farmers in Hawaii and other productive farming areas did for centuries: Leave the leaves at the base of the tree. Let them break down and insulate the soil, adding to soil fertility and moisture retention.

You can also do what my mentor at Foster Botanical Garden, Masa Yamaichi, did. He and his mom liked to grow orchids. Lychee leaves break down slowly, and Mrs. Yamauchi figured out they are perfect potting media for orchids, anthuriums and even tropical rhododendrons.

As you mow the grass, don’t blow. Let the grass dry a bit and rake that into a "mulch dish" around the base of the lychee and other good trees. Mix the grass and leaves for soil-building mulch.

Try these old techniques and let me know whether your lychee fruits this year. You can also water it if it gets hot and dry. Water by hand, just within the drip line of your lychee tree.

Water and soil fertility is something we can control in our own gardens. And every shady canopy tree that we plant produces oxygen with its hardworking photosynthesizing leaves. This process also cools the air and adds moisture.

Girdling is what frustrated tree abusers do. It does work, sort of. Girdling cuts off the flow of water and nutrients between leaves and roots. The nutrients are stuck in the leaf zone, and that plus the stress might cause the tree to flower and fruit. Doing it to much or too deeply could kill the tree over time.

Heidi Leianuenue Bornhorst is a sustainable landscape consultant specializing in native, xeric and edible gardens. Reach her at heidibornhorst@gmail.com.