Planting and Soil Preparation
These two items are like ham and eggs, one goes with the other. Proper planting and soil preparation are imperative for California natives and applies equally to non-native plants. After much thought, I decided that an illustration depicting the planting technique was worth a 1,000 words. The numbers in the illustration correspond to the numbers in the discussion.
The best time of the day to plant is in the cool of the evening when lengthening shadows will prevent the plant from being dehydrated by the sun. The best time of the year to plant is in the fall/early to mid winter when cooler weather will not stress the plant. Planting during hotter portions of the year will place excessive demands on the root system to provide water to meet the plant’s increased transpiration (loss of water through the leaves).
1. Digging the hole: For sandy soil, dig the hole half again as deep and at least twice as wide as the plant container. For clay soil, dig the hole twice as deep and at least three times as wide as the plant container. Break up large clods and remove any rocks. In both types of soil, dig a square hole and not a roundish hole. This helps the roots grow into the surrounding native soil when they reach a corner. Notice how happy your plant appears?! They do that when they know they will receive the right TLC. Is this great or what!?
Soil amendment: To begin with, the native soil should be soft and crumbly. The sand and clay soils native to our area certainly can use some improvement. The sand tends to be nutrient poor and dries almost too quickly while the clay, more abundant in nutrients, tends to retain water too well for most native plants. Both types will benefit from amendments. For me, partially decomposed compost or wood chips work quite well. They provide nutrients and water retention for sandy soil and provide extra drainage for clay soil. If this is not available, nitrolized redwood or fir bark (it should be of a fine texture) works quite well. Do not use plain woodchips or bark; bacteria, in the process of breaking it down, will remove nitrogen from the surrounding soil. This includes the plant’s root ball thereby robbing the plant of needed nutrients for growth.
For clay or sandy soil, use approximately a 50/50 mix of soil to compost/bark. Mix well and put aside for backfilling the planting hole. Fill the planting hole with water and allow to percolate into the subsoil.
2. Place some of the backfill material into the hole, moisten, and tamp firmly. With the plant still in the container, place in the hole and check the level of the plant crown to the finished grade (see illustration). Add or remove backfill as necessary so that the plant crown is 1" higher than finished grade.
If you haven’t watered the plant in the pot the evening or morning before planting, now is a good time. If you water now, set the plant aside for about 30 minutes to allow the root ball to drain. A root ball that is too dry will fall apart when removed from the pot. Believe it or not, so will one that is too wet.
Now that the plant crown height is correct; remove the plant and pot, give the pot a few firm squeezes around the perimeter, place your hand on top of the pot with the main stem between your middle fingers, invert the plant and pot making sure there is enough room between the top of the plant and the ground so as not to damage the top growth, and gently pull the pot away from the root ball. If the plant appears to be very root bound, use a pair of hand pruning shears and cut the root ball in four places from top to bottom. Place the happy plant into the hole and adjust for vegetative display, i.e. how does it look.
3. With water flowing slowly from a hose into the hole, replace backfill material up to approximately 2/3 the height of the root ball. Moistening, tamping firmly, and settling all around. Fill the remaining portion of the hole with water and allow to percolate into the subsoil/backfill.
4. Fill the remaining portion with more backfill, moisten, and tamp. Make sure that the plant crown is at least 1/2" to 1" higher than the finished grade.
5. Create an irrigation basin berm at least one plant container width beyond the outer edges of the hole with the remaining backfill and native soil as necessary.
6. Apply a generous portion (approximately 1" deep) of well decomposed compost or wood chips around the inside of the entire basin area. Do not pile the material up against the plant crown. This will promote root/crown rot. On top of this material, apply another generous portion of mulch or wood chips. The well decomposed material will act as a slow release fertilizer for the plant and the mulch/wood chips will keep the roots and surrounding area cool and moist.
Before discussing initial care, I need to mention the need to wean drought tolerant plants from the nursery watering schedule. In most cases their schedule is every other day but could be as frequent as every day. This certainly meets the plant’s water needs but also tends to promote soft growth with larger than usual leaves and will result in a plant that is unable to tolerate normal water loss. Just transplanting will result in stress to the plant. Also a root system that always receives plentiful water will not be as robust as one that is kept on the dry side. Plants send out roots in search of water; if they receive plenty of water why grow an extensive root system. Worse yet is a plant that has been at the nursery for a long time. The frequent watering will quickly leach the nutrients out of the soil and the plant will appear stunted with small, yellow leaves or few leaves. It may also be root bound. Don’t buy this plant!!
After purchase, water the plants. Place those plants that can tolerate full sun in a location that receives plenty of morning and afternoon sun but, preferably, no noon sun. Then reduce watering to every 3 days for three waterings, then to every 4 days for three waterings. The whole process takes about 21 days; time consuming but worth the reduced transplanting stress and watering schedule. When you are ready to plant, water the evening prior or that morning no matter when the last watering occurred.
Initial Care
Watering: For the first two months after planting, no matter when you plant, it is imperative that the root ball does not dry out. A little tip here: water will flow from a coarse soil to a fine soil but not vice versa. The soil of the root ball is coarse while sand and clay are fine. After planting, water about once a week in the cool of the morning or late evening and water the basin and the root ball. Never water during the heat of the day or when the sun is at it’s most intense. Watering should be done before 9:OOam or after 6:OOpm. Think of it as breakfast and dinner for the plant. Watering during the heat of the day or when a plant is showing signs of stress due to lack of water is a sure way to kill it. I’m saying this from more experience than I want to admit. Monkey flowers (Mimulus species) are extremely susceptible to death from improper watering practices. After about two months, reduce the watering to once a month but water deeply. During the summer and early fall, before the rains start, watering deeply approximately every two to three weeks is sufficient for sand. For clay, deeply water every three to four weeks during this period. Keep the basin well supplied with mulch as required.
This watering routine will be quite adequate for most native plants. There are some, however, that will only tolerate an initial watering when planted. Any watering after that except for normal, rain will kill them. The Island bush poppy (Dendromecon rigida subspecies harfordi) is one such plant.
Fertilizing: I do not recommend using any commercial fertilizer unless you really must. If you do not have a source of mulch, wood chips, or compost then use of a slow release fertilizer is a good substitute. Use a balanced fertilizer and use half of the recommended amount. Feed after the first 1" of rain in the fall and then again in mid-April. The best fertilizer is still the generous, decomposing layer of mulch around the plant.
