By Susanne von Rosenberg, UC Master Gardener of Napa County

One of the things that I like most about spring is the beauty of flowering trees. It's just stunning to see a magnolia or almond tree in full bloom. Flowering trees are really one of the easiest and most rewarding ways to beautify your yard, and you get the added benefit of shade in the summer.

You have two primary options for flowering trees. You can plant fruit or nut trees, or you can plant ornamental flowering trees. Fruit trees will require more care, because in addition to keeping the tree pruned properly, you also need to manage the fruit load and potentially address pests and diseases. For me, the extra effort is worth it.

The size of the tree should be in proportion to the size of your lot. For parcels smaller than a quarter-acre, choose trees that will be less than 25 feet high at maturity.

Plant trees away from the foundation of your home. Even smaller trees that will be less than 25 feet tall at maturity should be planted at least 10 feet away from the foundation.

Find out how wide the tree canopy will be at maturity and allow for a gap between the side of the house and the canopy. Plant smaller trees at least 25 feet from other small trees. Your tree needs at least 100 square feet free of hardscape.

Think about where the mature tree will cast shade. Be sensitive to how the tree might affect your neighbors' view and access to sunlight. Utilities are another consideration. We've all learned not to plant trees under power lines, but you also want to avoid areas close to sewer, septic or water lines and septic tanks and leach fields. Don't plant your tree over other underground utilities either. Electrical lines, gas lines and fiber-optic cables can all be affected by tree roots. Your tree might have to be removed if it impedes maintenance or repair activities.

Finally, choose your tree carefully. Fast-growing trees may seem desirable, but they often end up getting too tall or dying quickly. Before you purchase any tree, make sure that it's not considered invasive in Napa County. Also, find out whether the tree you want may serve as a host for diseases affecting other trees. For example, ornamental pears are often affected by fire blight and serve as a repository of the bacteria. Fire blight is the biggest threat to the health of pear, apple and quince trees.

Some of the best flowering trees for Napa County include almonds, cherries, nectarines, peaches and plums. All are beautiful in bloom. Many small, purely ornamental trees also do well in our area.

All of the following trees are less than 25 feet tall at maturity. Most are considered “patio trees,” meaning that they usually grow less than 15 feet tall. Many of them naturally grow as tall shrubs and can be trained into a tree form. Most of them are also drought tolerant once established.

Australian tea tree (Leptospermum laevigatum) grows 10 to 30 feet tall, is evergreen, and is covered by long-lasting white flowers. New Zealand tea tree (Leptospermum scoparium) cultivars are usually smaller, ranging from 6 to 8 feet in height, and come in colors ranging from white to pink to magenta.

Ceanothus, also called California lilac, includes 50 to 60 species of nitrogen-fixing shrubs and small trees. The cultivar ‘Ray Hartman' can grow 20 feet tall and has medium blue flowers. However, most cultivars are much shorter.

Chitalpa (Chiltalpa x taskentensis) generally tops out at less than 25 feet tall. It has grayish-white bark and tolerates a relatively wide range of soils. The flowers of the two most common cultivars are white to very light pink, and light pink.

Desert Catalpa (Chilopsis linearis) has narrow linear leaves and fragrant flowers ranging from white to pink to lavender. It grows 10 to 30 feet tall and with age develops shaggy bark and a twisting trunk.

Feijoa sellowiana (pineapple guava) is an evergreen, has gray-green foliage and beautiful flowers with edible white petals and red centers. The tree flowers in late spring and yields guava-like fruit in the fall. It can grow 10 to 15 feet tall.

Western redbud (Cercis occidentalis) grows 10 to 20 feet tall and has pink or magenta flowers. It is native to California and other parts of the West and prefers moister areas to hot, dry areas.

One of my favorite small trees is California Flannelbush (Fremontodedron californicum). It has bright yellow flowers and can grow up to 20 feet tall in five years. It is finicky about water so make sure you can meet its needs before planting one.

Free Library Talk: UC Master Gardeners of Napa County will conduct a talk on “Growing Culinary Herbs” via Zoom on June 3 from 7 pm to 8 pm. Register to receive the zoom link: http://ucanr.edu/2021JuneGrowHerbs

Workshop: UC Master Gardeners of Napa County will lead a free workshop on “Worm Composting” on Saturday, June 12, from 10 am to noon, via Zoom.

Learn how to turn your kitchen scraps into rich compost with red worms. All attendees will receive all the materials necessary to make a worm compost bin at home. Pick-up arrangements will be made after you register; limit one bin per family. Register for "Worm Composting with Penny at City of Napa Home Composting Workshops 

Got Garden Questions? Contact our Help Desk. The team is working remotely so please submit your questions through our diagnosis form, sending any photos to mastergardeners@countyofnapa.org or leave a detailed message at 707- 253-4143. A Master Gardener will get back to you by phone or email.

For more information visit http://napamg.ucanr.edu or find us on Facebook or Instagram, UC Master Gardeners of Napa County.

By Penny Pawl, UC Master Gardener of Napa County

In the first old house my husband and I lived in in downtown Napa, we had the second floor and access to the attic. When we moved in, we had no idea there were bats in the attic. My first encounter was when I went to mop the floor and there was a funny looking “mouse” in the bucket.

I had just seen a Dracula movie and you can guess what I was thinking. After six years of living with bats and having no insects biting us, we had adjusted well to our fellow tenants. The only downside was cleaning up their guano.

When I visited Morocco a few years ago and camped in the desert, bats started flying around our tent during dinner. They were after the bugs flying around the light; they did not bother the other diners or me. After everyone finished eating, I stayed and watched the bats and tried to get a picture of them. Photographing a flying bat is not easy.  

On a trip to Bangkok, I saw beautiful fox-faced bats hanging from the trees that we walked under.

I know we have bats right here in Napa County. I have seen them, and according to what I have read about them, we should be happy they are here. One bat can eat as many as 3,000 insects in one night.

Bats are mammals that give birth to live young. How they do that when hanging upside down is quite a feat.

There are 27 species of bats in California and 7 species in Napa County. Worldwide, there are 1,200 species, including the vampire bats of South America and the fruit-eating bats of Asia. Most of the California species nest in trees, while others nest in caves or rock outcroppings. We don't see them unless we are out at night when they are hunting for insects.

A few bats are also important pollinators. On the East Coast, white-nose syndrome, caused by a fungus, is killing many bats that nest in humid caves. In California we do not have this problem; however, many California bats are killed annually by large wind turbines.

Vineyard owners in California welcome bats because they eat insects that harm grapevines. Several organizations are dedicated to saving bats and educating the public about them.  

Bats are said to seek houses or other enclosed spaces when they are reproducing and caring for their young. A few years ago, I purchased a bat house, painted it and hung it as directed on the sunrise-facing side of a tree.   Droppings at the base of the tree would indicate that they were resident, but so far, I have not found evidence that they ever moved in.

Some sources advise putting bat houses under a roof overhang, but I have had enough bat guano in my life and decided not to do that. Another option is to hang the house from a pole at least 15 feet above ground. You can find a lot of information online about how to build and erect a bat house.

Some people believe that bats are blind, but this is an old wives' tale. They use both their eyes and ears and have better vision than we do. They are not related to mice. The average lifespan in the wild is 20 years, although one bat was known to live 40 years. They typically produce one bat baby, or pup, each year.

If you see a bat on a bush, on the ground or under bark on a tree, don't pick it up. Bats can carry rabies. A group of rabid bats was recently found on the UC Davis campus. Although fewer than one percent of bats are rabid, you should avoid them just in case. If you are bitten by a bat or get bat saliva on you, see a doctor at once.  

Here is some information from UC IPM Pest Notes on bats:

http://ipm.ucanr.edu/PMG/PESTNOTES/pn74150.html

Workshop: UC Master Gardeners of Napa County will conduct a demonstration workshop on “Harvesting Your Compost from a Backyard Pile or Worm Bin” on Wednesday, May 26, from 6 pm to 8 pm, via Zoom. Register to get the zoom link at: City of Napa Compost Workshops

Got Garden Questions? Contact our Help Desk. The team is working remotely so please submit your questions through our diagnosis form, sending any photos to mastergardeners@countyofnapa.org or leave a detailed message at 707- 253-4143. A Master Gardener will get back to you by phone or email.

For more information visit http://napamg.ucanr.edu or find us on Facebook or Instagram, UC Master Gardeners of Napa County.

by Penny Pawl, UC Master Gardener of Napa County

I love hellebores because they stay green all year, bloom in the winter and don't take a lot of water to keep them happy. Hellebores are called Lenten roses by some because they start to bloom around the time of Lent. But they are not roses.  

The flowers have some resemblance to roses but the colorful petals surrounding the flower are not part of the flower. And the petals remain on the stem for several months even after the flower in the middle has faded.  

Native to the Balkan states and parts of Europe and Asia and named hellebore in the 1700s, this genus has been hybridized since then to include many beautiful colors. My first hellebore, a green one, has produced offspring identical to the parent. However, since most hellebores for sale today are hybrids, any seedlings that emerge in your garden will probably not resemble the parent plant.

I have been collecting hellebores in various colors and especially like the pink and two-toned types. I grow them on the mound in my back garden as they seem to like slopes and look nice during the cold months when I can see them from the house.

Hellebores grow well in shady areas. Nurseries sell them in gallon cans so they are easy to transplant. When you do, be sure to remove some of the container soil and mix it with your garden soil. I also put a tablespoon or two of worm compost under the plant and then water well.

If you are an adventurous person, you might want to try planting hellebores from seed. You can find seed sources online. You will have a surprise when they bloom and you discover the bloom color. Seedlings do not bloom until the second year so you will need to be patient.

In winter and spring, when your hellebores start to bloom, feed them with a natural fertilizer such as aged chicken manure or worm compost. The latter has all the necessary trace elements in a mild form. The plants go dormant in summer, but you should continue to water them.

If you like the bloom color of one of your hellebores, you can reproduce the plant by division. Wait until it has finished blooming, then dig around the root ball and lift it out. Hellebores have fibrous roots that are easily divided. Take a rooted piece or two and replant where you want them, then return the rest of the clump to the original hole.

Another method for reproducing hellebores is called micropropagation. I doubt any of us will want to try it. It involves placing a piece of the plant in a sterile test tube and treating it with hormones to stimulate growth. When the plant is big enough, it is transferred to a pot.

I saw this method used on cymbidium orchids years ago at an orchid grower in San Francisco. It is also called meristem propagation. I enjoy propagation but I don't think I am ready to attempt this method quite yet.

I have noticed few pests on my hellebores over the years. Deer, mice and gophers leave them alone because they are toxic, and few other pests bother them. Some online sources mention aphids, but I have never seen any on mine. I practice integrated pest management, so perhaps other bugs are feasting on whatever might attack my hellebores.

Workshop: UC Master Gardeners of Napa County will conduct a demonstration workshop on “Harvesting Your Compost from a Backyard Pile or Worm Bin” on Wednesday, May 26, from 6 pm to 8 pm, via Zoom. Register to get the zoom link at: City of Napa Compost Workshops

Got Garden Questions? Contact our Help Desk. The team is working remotely so please submit your questions through our diagnosis form, sending any photos to mastergardeners@countyofnapa.org or leave a detailed message at 707- 253-4143. A Master Gardener will get back to you by phone or email.

For more information visit http://napamg.ucanr.edu or find us on Facebook or Instagram, UC Master Gardeners of Napa County.

By Susanne von Rosenberg, UC Master Gardener of Napa County

As a gardener, you are doubtlessly painfully aware of how little rainfall we had during our last rainy season. According to the United States Drought Monitor, Napa (along with more than 50% of the entire state) is currently in an exceptional (category D3) drought.

Some counties have already imposed water conservation requirements. We can count on Napa County and its cities having to do so as well.

During an exceptional drought, fire season lasts year-round. Water is inadequate for agriculture, wildlife and urban needs, and reservoirs are extremely low. In addition, our soils are already pretty dry and cannot serve as a reservoir for our plants in the late spring and early summer, as they normally do.

So, knowing that water conservation requirements are coming, your plants need irrigation sooner than they would during a normal rain year. As a good steward of the planet, what can you do to better prepare your garden to use less water?

In addition to continuing to make your garden more water-wise in general, you can take specific steps now to reduce the water needs of your garden. Make yourself a checklist and make May your drought-preparedness month.

Two of the easiest things you can do to use less water are to mulch your garden and to move to drip irrigation wherever possible. Before you mulch any part of your garden that isn't currently mulched, make sure that you water well so that the soil is moist below the mulch. Then install drip irrigation, and mulch over the drip irrigation, if possible. If you install irrigation over the mulch, water will have to moisten the mulch first before it can penetrate to the soil.

If you are currently hand watering or using sprinklers, installing drip irrigation will help ensure that the only the plants that need water are getting it. You can easily install a drip system yourself. Drip irrigation waters slowly, which means the water has time to penetrate the soil. You save water by preventing run-off and evaporation, and you get fewer weeds.

Then make sure you only water when necessary. For annuals and shallow-rooted perennials, it's time to water when the soil is dry two inches down. For trees, you can wait until the soil is dry at least six inches down. Get to know your plants and understand what signs of water stress look like.

Given that we are in an exceptional drought, the more you do to conserve water in your garden, the better. Another important tool in water conservation during a drought is to prune your trees hard. Preserve leaf canopy that provides shade to your house and other plants but reduce the size of ornamental and fruit trees that don't provide a direct shade benefit.

The smaller the tree, the less water it will need. You can safely prune back fruit trees by one-third. If you expose any limbs that have previously been shaded by leaves, paint them with white interior latex paint (diluted with an equal amount of water) to protect them against sunburn. You should also thin fruit on fruit trees to reduce water demand and get better fruit.

You can reduce the water needs of delicate plants by creating afternoon shade for them. Install shade cloth or other materials to block the afternoon sun.

Think about what parts of your garden are most important to you. You may have to decide not to water certain plants. What are your priorities? You'll probably want to focus on saving perennial plants, especially trees. Although I have a vegetable garden, I would definitely let that go in favor of watering my fruit trees.

You can also rethink your garden. Are there parts that are particularly thirsty? Maybe this is the year to remove those plants, and plan to replant in the fall with more drought-adapted plants.

If you have any unneeded lawn, consider replacing it. Stop watering it and work on a replacement plan to implement in the fall.

Delay any new plantings until we get adequate rain unless the new plantings will require considerably less water than what they are replacing.

Finally, know that your perennials can survive on less-than-optimal amounts of water. When plants lack water, they conserve by closing the stomata (openings) in their leaves that allow water to evaporate. Photosynthesis stops because the plant is no longer getting any carbon dioxide from the air. The result is that the plant won't grow as much as it would with optimal water. Let it catch up in a wetter year.

I encourage you to start now to conserve water, doing your share to help make sure we have enough water to go around.

Food Growing Forum: On Sunday, May 9, UC Master Gardeners of Napa County will host a discussion on “Beans and Summer Pruning of Fruit Trees” from 3 p.m. to 4 p.m. Register to get the Zoom link.

Library Talk: On Thursday, May 6, from 7 pm to 8 pm, UC Master Gardeners of Napa County will hold a virtual talk on “Right Tree, Right Place: Making Smart Tree Choices for Your Landscape.” Register to get the Zoom link: http://ucanr.edu/2021MayRtTreeRtPlace

Tree Walk: On Tuesday, May 11, from 10 am to noon, UC Master Gardeners of Napa County will host a docent-guided tree walk in Fuller Park in Napa. Group size is limited to seven. To register: https://bit.ly/2Qg3tib

Got Garden Questions? Contact our Help Desk. The team is working remotely so please submit your questions through our diagnosis form, sending any photos to mastergardeners@countyofnapa.org or leave a detailed message at 707- 253-4143. A Master Gardener will get back to you by phone or email.