Eons before the arrival of human beings to the place now called Del Mar on the Southern California coast, there was one dominant tree species growing there, the Torrey pine (Pinus torreyana).

The wild groves of these trees still in existence were once part of a much larger forest that, probably due to climate changes, shrank to the limited area we know today.

Photo by TheNose

In the 16th century these trees served as a prominent landmark to seafaring Spaniards on an otherwise bare coast. They gave the name “Punta Des Arboles”, the Point of the Trees, to the current location of Torrey Pines State Reserve.  Today the Torrey pine is cultivated in Mediterranean climates around the world, but it grows in the wild in only two places, in the Del Mar/Torrey Pines area and on Santa Rosa Island, 175 miles off shore. Called “Soledad Pine” by the Spaniards, the species was renamed in 1850 by Dr. Charles Christopher Parry, a traveling botanist, in honor of his friend, Dr. John Torrey, the greatest botanist of his time.

For centuries before the arrival of Europeans, the Torrey pine was an important source of  food and craft materials for local Kumeyaay Native Americans. In fall they gathered the nutritious nuts off the ground. They used the sap to make glue and sealant and the needles for coiled baskets. By the time Del Mar was settled, the wild pine trees had split into two groves, one on the north end of the hill and the other on the south, echoing the larger grove on the opposite side of Penasquitos Lagoon. With great foresight, Miss Ellen Browning Scripps purchased the headland south of the lagoon to protect the trees and topography from destruction, and it was through her generosity that it became the nucleus of Torrey Pines State Reserve.

A  Heritage Tree

Torrey pines live in symbiotic relationship with the scrub jay. The jay eats the seeds or buries them in the ground for future use. Because the seeds have a hard shell only buried seeds can stay damp enough to germinate, but thanks to the scrub jay new Torrey pines constantly sprout on the cliffs of Torrey Pines Park. During dry years wild trees decline and die from beetle attack, but the scrub jay never stops replenishing the forest. In many coastal zones of Southern California, however, there is adequate ground moisture from irrigated gardens to insure that few Torrey pines succumb to beetles. Where Torrey pines are already growing the seeds sprout even more readily when buried by jays or covered by mulch, than on dry wildlands. Additionally, many coastal communities treasure the Torrey pine for its unique history. In Del Mar this tree has become the “heritage” tree, and is protected by statute.  All Torrey pines with trunk diameter greater than 12 inches and farther apart than 12 feet from houses or from one-another are protected by local statute. In the City of Del Mar, one needs a permit to cut down a Torrey pine tree, though judicious pruning is allowed without a permit.

Where to Plant a Torrey Pine

If purchasing a container-grown Torrey pine, choose a smaller, more vigorously growing specimen. Smaller trees get going much faster than large ones. Take off the nursery stake if there is one. The ties can damage trees. Most conifers don’t need staking, and a tree must move in the wind to develop a strong trunk. Plant Torrey pines in full sun and in well-drained soil away from lawns, pipes, concrete walks, and buildings. The roots of this tree can travel far beyond the spread of their branches and will invade broken sewer pipes if given a chance. The water required by a lawn will create too much growth in a Torrey pine. Torrey pines in the wild are deep rooted and are known for their wonderfully windblown shapes, but a Torrey pine growing in a garden where it receives too much water can form shallow roots and become top heavy. In such circumstances, Torrey pines have been known to topple over from their own weight even on a windless day.

How to Dig a Planting Hole and Test the Drainage

When planting a Torrey pine, it is not necessary to amend the soil at planting time. Dig a hole that is twice as wide as the plant container and one to two inches less than the depth of the rootball. Before planting any tree it’s a good idea to test the drainage in the hole. To do this, fill the planting hole with water and let the water drain out. Then fill the hole a second time, lay a stick across the top of the hole and measure the distance from the stick to the surface of the water.  If the water level doesn’t drop at least one-quarter inch each hour, dig another hole in a location with better drainage. If the water level drops one-tenth of an inch per hour or slower, drainage is too poor for most cultivated plants.  In this case you will need to find a better planting spot.

How to Plant a Torrey Pine

Place three Tree Tabs (slow- release, fertilizer tablets designed to be buried in planting holes) evenly spaced around the edges of the bottom of the hole. Loosen the roots of the tree, making sure they don’t wind around and around, then place the root ball in the middle of the hole and check that the top of the root ball is the same height or a little higher than the surrounding soil. If you are planting in clay soil, mix three cups of gypsum into the earth from the hole before backfilling. This can help break up the soil and improve drainage. Backfill with the native soil you removed from the hole. Don’t add any manure or bagged planter mix. Use the excess native soil to build a ridge at the outer edge of the root ball and water deeply immediately after planting. Water deeply once again the following day. (A drip system does not provide sufficient irrigation for any newly planted, container-grown tree.) Thereafter, water three times a week for the first two weeks and twice a week for the next two weeks. After that, water deeply once a week for the first two months.

Enlarging the Watering Hole, Weeding, and Scheduling Irrigation
Two months after planting your Torrey pine, enlarge the watering basin so it will be two to three times wider than it was before. Now begin watering twice a month and finally once a month. Control grass and weeds growing within two feet of the trunk, since they compete with the tree for water and nutrients. After the tree is one-year old, water once a month under the drip line of the tree (the branch tips) during the summer and early-fall only. Once your Torrey pine is three years old, fully established, and deeply rooted, no further irrigation should be necessary.  It is never wise to water any full-grown tree right next to the trunk. The area around the trunk of a mature tree is called ‘the crown” and watering in that location can cause “crown rot”. There are no feeder roots close to the trunk of a full-grown tree. All feeder roots are away from the trunk out under the drip line and even out further. Even in drought years there is usually adequate moisture in most parts of Del Mar to allow a Torrey pine to remain in good health without any artificial irrigation. However, if a tree shows stress in summer or early fall, one deep and slow watering in September will often be enough to pull it through. Set a sprinkler under the drip line of the tree and allow the water to run slowly and long enough to sink into the ground and not run off.

Fertilizing of Torrey Pines

Unless a Torrey pine is growing in pure sand, no fertilizer is necessary for healthy growth. However slow-release fertilizer tablets at planting time, as described above, can help get the tree established. These trees are adapted to growing in the native clay and sandy soils found here and receive no fertilization in the wild other than that provided by decaying leaf litter, animal and bird droppings, and the occasional dead animal or bird that Mother Nature may throw their way.

Pruning of Torrey Pines

If a Torrey pine tree is in good health and does not have any dead growth in it, it may never need pruning. However, if a young tree develops two central leaders (trunks) one should be removed because the crotch will be weak and prone to splitting as the tree grows.  Also, when a Torrey pine has been over-watered or given fertilizer, or been grown in a lawn, it may grow too large and become dangerous. If this occurs, the tree may be safely pruned by a reputable tree company in order to lace out the tree to reduce the weight of foliage, shorten the length of the longest branches, and/or to lower its height in order to avoid overhead wires or other hazards. All pruning should be done in winter months between the beginning of November and the end of February before warm weather promotes extensive new growth of shoots and foliage. All cuts should be made at the outside edge of branch collars. (The branch collar is the thickened area or ridge that surrounds a branch where it meets the trunk or another larger branch.)

Any lowering of height or shortening of branches needs to be accomplished by drop-crotching. (Drop-crotching is a system of pruning by which a new leader is chosen farther down on the tree or further back on a branch.) Never allow a tree to be topped and never allow branches to be chopped off without leaving a remaining growth tip. (Topping is a discredited pruning system by which a tree’s height is lowered by cutting straight through branches or the trunk removing all tip growth further out or up from the cut. You will frequently notice this incorrect pruning method used on coral trees and eucalyptus.) Above all, when pruning, never remove more than twenty percent of the foliage of a Torrey pine tree at any one time. This rule applies to all trees, but especially pine trees, such as Canary Island pine (Pinus canariensis), for example, since the bark of pine trees can be damaged by sunburn, and this will often lead to stress and beetle attack. Pines need a healthy canopy of foliage to provide food for their root system. Over-pruning combined with incorrectly placed cuts weakens trees and can stimulate excessive growth on remaining branches.

Signs of stress in pine trees include loss of their healthy green color, yellowing or browning of the needles, wilting or drooping needles, and the development of an unusually large number of pinecones. In the hot weather of summer and fall, however, many of the older green needles on perfectly healthy Torrey pines will lose their normally grayish-green color. It is a perfectly natural process for old needles to go brown and sift to the ground as new needles mature and branches grow longer.  Instead of raking up the fallen needles and sending them to the dump, allow them to lie where they fall on top of the ground surrounding the tree. This long-lasting, natural mulch helps to preserve moisture in the soil, cuts down on weeds, and is beneficial to the Torrey pine.

Photo by Mano K