Swan Hill Nurseries

The Swan Hill Olive® was patented by the University of California, Davis, CA after nearly a decade of research. The unique qualities (fruitless and pollenless) of the Swan Hill Olive® have been authenticated by research, published in peer reviewed, scientific journals. In the thirty years since the patent was granted not a single study has refuted any of the results of this research. Swan Hill Nurseries, LLC has always had the option to grow other, so called, fruitless cultivars but we have always declined. If there was a better, more reliable, genuinely fruitless/pollenless olive variety we would grow it.

Some communities prohibit the planting of olive trees because of the pollen. How do I find out if I can plant The Swan Hill Olive® in my community?

Research conducted at the University of Arizona, Tucson, AZ and the University of California, Davis, CA showed that the The Swan Hill Olive® releases less than 1% of the pollen released by common European Olives. On the basis of this research The Swan Hill Olive® has been grant exemptions from olive planting prohibitions in most if not all communities.

How will I know that I have purchased a Swan Hill Olive®?

We are proud of the trees we grow and so confident in their unmatched qualities of non-fruiting, non-pollinating and wilt resistance that we place a uniquely numbered tag on each one. This tag assure you that you that the tree you purchased is the premiere landscape olive on the market; The Swan Hill Olive®. It confirms that the olive trees you plant are exempted from community policy restricting pollen producing olives.

I am a homeowner, where can I purchase a Swan Hill Olive®?

Swan Hill Nurseries, LLC is a wholesale nursery/grower and we do not sell directly to the public. Visit our Distributor page for a retail outlet near you.

As a landscape contractor, can I buy Swan Hill Olives® directly from you?

Yes, you can buy directly from Swan Hill Nurseries, LLC or from one of our distributors. Visit our Distributor page for a Wholesale distributor nearest you. Look for the tags. If you don't see the Swans, you didn't get The Swan Hill Olive®.

What sizes of Swan Hill Olives® does Swan Hill Nurseries, LLC produce?

Swan Hill Olives® are sold exclusively in 24", 36", 48", 54" and 60" boxes.

What are the specifications (height, width, caliper) of the Swan Hill Olives® in their respective box sizes?

Specifications will vary depending on the level of sales pressure on our inventory and the season of the year. We try to keep our specifications up to date and reported in the Box Sizes and Specifications section of our web site.

Will I find the same specifications when I buy from your distributors?

It is probably advisable to contact individual distributors for their specifications. Generally, distributors face the some of the same production challenges we do. Many take our 24" boxes and bump them into larger sizes so the specifications of these trees will depend on how long the distributors are able to keep them in inventory before someone buys them.

Why are Swan Hill Olives not available in smaller sizes?

Swan Hill Olive® trees are grafted to the Oblonga rootstock that is resistant to Verticillium Wilt fungus. To insure that the rootstock is under control we do not market trees smaller than 24" boxes.

Is the Swan Hill Olive® available in different forms?

Yes, the Swan Hill Olive® is available as true multiple trunks, Low breaking trunks and single or standard trunks. Multiple trunk specimens have at least three trunks originating at or near the soil line. Low breaking trunk are technically multiple trunk trees in overall appearance but the trunks originate anywhere from 6" to 18" above the soil line. Standard trunk trees have anywhere from 2' to 5' of clear truck. You can see photos of these forms in the Box Sizes and Specifications section of our web site.

How many trees can I expect to get in a truckload?

If you check in Box Sizes and Specifications section of our website, the pages for the individual box sizes will list how many trees can be loaded on a Semi-trailer truck.

How fast do Swan Hill Olives® grow?

The growth rate of the non-fruiting Swan Hill Olive® is considered to be "moderate" as compared to the designation of "slow" growing typical used to describe the growth of fruiting European Olive varieties. Fruit production in the common European Olive requires a great deal of nutrients over the 6 month fruit bearing season. The nutrients and energy diverted to fruit production comes at the expense of vegetative growth (leaves, limbs, roots, etc.). The absence of fruit production in the Swan Hill Olive® means the tree can use all of the nutrients, energy and water for upward and outward vegetative growth all year, every year. It is not unusual to see an average growth rate of two feet plus per year under ideal conditions within for the first 10 years following planting. Carefully pruned multiple trunk Swan Hill Olives® usually reach a mature height of 30 feet by 20-30 feet wide. Under ideal conditions they can easily grow to 35 foot tall by 30 wide in 10-15 years following planting (depending upon the original box size planted and climate). Trees that grow at a similar rate in the deserts would be Blue Palo Verde and Jacaranda. Some of the misconception about growth rate has to do with the difference between strongly columnar trees like Elms and Ashes and the more radial or shrub-like growth of olives trees. Both grow at similar rates with the columnar trees gain height rapidly while radial grow in multiple directions simultaneously.

In what zones can plant the Swan Hill Olive®?

Swan Hill Olives® are well adapted to zones 8, 9 and 11-24 (Western Garden Book, Sunset Books, June 1997). Sheltered microclimates that are protected from hard freezes (28 to 26 degrees F) may also be suitable.

When is the best time to plant Swan Hill Olives®?

As a landscape staple in the southwest, Nevada and California, Swan Hill Olives® are planted year round by landscape professional and home gardeners alike.

How often should I water my Swan Hill Olive®?

There are no hard and fast rules on tree irrigation schedules. How often you irrigate will depend on the age of the tree (freshly transplant versus established/mature), soil type, water penetration rates, under story plantings and their irrigation schedules and water drainage from other areas of the site (rain water from roof, general site drainage, hardscape elements), to name a few. See our Planting and Maintenance page for information on post installation irrigation. Ideally, established Swan Hill Olives® should be irrigated in such a way that the soil is initially saturated then allowed to drain and dry slightly before water is reapplied. The rate at which this occurs will depend on the elements listed above. The top 18" to 24" of soil are the most critical to irrigate for the 24" to 36" box trees. Monitoring this profile of soil will help you schedule your irrigations. If you have a soil probe, take a core of soil from about mid way between the trunk and the end of the leaf canopy (drip line). The probe will usually stop when you hit dry soil. If the top 18" to 24" of soil is still wet, there is no need to irrigate. Wait a day or two and test again. When the soil appears moist and the top inch or so is somewhat dry, it is a good time to irrigate. Repeat these soil samples in combination with your irrigation schedule a time or two and you will get a sense of how quickly your soil is draining and how rapidly your Swan Hill Olive® is taking up water. If you don’t have a soil probe, a 3/8 to 1/2" diameter piece of rebar will also work. The probe will stop when it hits dry soil and the ridges on the rebar will catch bits of soil that you can examine for water content. The soil type and drainage at the bottom of the planting hole will influence water application. Larger, field dug trees (48" boxed and larger) trees that are planted in well drained soils, under hot summer conditions, and initially irrigated by drip or bubbler-like irrigation systems, should be deep watered at planting and every 10 days to two weeks for 60-90 days. This assures an adequate supply of water to the bottom of the root ball.

Remember that new roots only grow into moist soils. One of the goals of irrigation is to develop a well dispersed root system that will allow trees to capture the optimal amount of water from the soil and provide the tree with solid anchorage against the force of the wind. This is best accomplished by applying water slowly and deeply from the trunk to the edge of the canopy. The heavier the soil (soils with high clay content) the slower the water penetration rate. Lighter, sandier soils may require more frequent irrigation.

Can I plant my Swan Hill Olive® in a lawn area?

Yes. Swan Hill Olives® can be planted in both lawn and desert adapted landscape design. Olives, in general, do not tolerate saturated soils (wet feet), especially within the first 6 to 12 months following transplantation (See Planting and Maintenance). Plant trees so that the soil line in the box is slightly above the final grade. This will insure that water will drain away from the tree in the event of over watering or heavy rains. It is important to note that "sodding" (the planting of sod in rolls) should not occur within the drip line of the tree (the area from the trunk to the outer edge of the leaf canopy. Similarly, the area beneath the drip line should not be overseeded with winter rye grass for 6 to 12 months following transplantation.

I see flowers on my Swan Hill Olive®, does that mean that it will bother my allergies?

The Swan Hill Olive® produces flowers in the same way common European Olives do. What makes the Swan Hill Olive® unique is that the anther (pollen producing portion of the flower) never opens up and consequently less than 1% pollen is released, compared to the common European Olive.

My Swan Hill Olive® is producing a few fruit that are about the size of pencil erasers, what should I do?

When the Swan Hill Olive® flowers, some swelling of the female portion of the flower (the pistal) may occur, giving the impression that the production of the mature black fruit has been initiated. This enlargement is due to a form of non-sexual reproduction called parthenocarpy. Parthenocarpy is the formation of "fruit" without pollination. In the Swan Hill Olive® this results in a type of "false pregnancy", where these false fruit ("shot berries") will abort, dry-up and abscise (fall from the tree). Since these "shot berries" are mostly water, they dry up rapidly and quickly disappear, leaving little or no trace.

Just to be on the safe side should I spray my Swan Hill Olive® with Olive Stop or other chemicals to prevent fruiting?

The Swan Hill Olive® is rendered fruitless by a genetic anomaly unique to this olive variety. It has been observed that the Swan Hill Olive® is highly sensitive to spraying with Olive Stop, Maintain®, Ethereal®, and other similar products. Leaf deformation, yellowing and overall stunting can result from using the recommended rates for the European Olive and other trees. If you own Swan Hill Olives® and live in an area where olives are routinely sprayed for fruit and flower control, advise you landscape maintenance or pest control operator to NOT spray your Swan Hill Olives®.

There are branches coming up from near the soil line with leaves that are a different color from the other leaves, what are they and should I be concerned?

These low branches, called suckers, are growing from the Oblonga rootstock and should be pruned off. These branches should be removed as they can produce olives if they are allowed to mature.

My Swan Hill Olive® is losing it leaves, should I be concerned?

Evergreens, like the Swan Hill Olive®, differ from deciduous trees in that, instead of losing all their leaves in the fall and winter, they lose some leaves year round. Leaf shed by evergreens can be relatively constant, a few leaves daily or weekly, or in small bursts, dozens of leaves a day for a week or more. Yellowing (bright yellow) and dropping of older mature leaves, at the base of the branch usually occurs in the fall and spring prior to flowering. This is normal. These heavy leaf drops can cause concern but are generally to be expected. Sometimes heavy leaf shed is associated with over watering, either in the form of too frequent irrigation or severe flooding caused by excessive seasonal rain, but in this case the younger newer leaves at the branch tips yellows and new growth is dry and not fresh and green. The tree also takes on an overall yellow cast. With over watering leaves appear dull green to mottled yellow.

Under watering will cause trees to take on a yellow cast, with leaves usually curled, cupped and feel dry to the touch. Unfortunately this symptom is also seen where irrigation or rain water stands around the base of a newly planted tree or soil is saturated for a week or more. Leaves may not even have a chance to yellow but quickly curl, die and hang on the tree.

Who should I contact if I am having trouble with my Swan Hill Olives® or have questions not covered on your website?

If you have specific horticultural questions related to growing Swan Hill Olives® in your area we suggest you contact your local distributor first as they will be more knowledgeable of your area and any unseasonable weather conditions in your region. If you still have questions then please contact us at info@swanhill.com and we will do our best to address your questions.