Garden Guide: Paeonia-Pyrethrum
Paeonia - Pyrethrum
PACHYSANDRA terminalis cultivars - Japanese Spurge
PLANTING: Space 6-10 inches apart. Grow in soils with a pH range of 5.0 to 7.0. Plant in a moist, well-drained soil in semi-shade or shade. MAINTENANCE: Never allow soil to get excessively dry; otherwise, they require very little maintenance. Zones 4-9.
PAEONIA species and cultivars - Peony
PLANTING: Space plants 3 ft apart in full sun or light shade, the latter being preferable in southern-most zones. The ideal soil is rich and moisture retentive, but well drained. When planting, set the root clumps in the hole so that the “eyes” or growing points are covered with no more than 1-2 inches of soil. Do not plant too deeply or your peony will not prosper. MAINTENANCE: It is vital that these plants be kept well watered during their growing season. As peonies are heavy feeders, fertilize each spring with a high phosphorous fertilizer after growth has started. When cutting, remove as little foliage as possible, since the leaves are necessary for plant growth and vigor. Remove spent flowers and, in the fall, cut back dead foliage. Established plants prefer not to be moved. In situations exposed to heavy winds, staking or a plant support hoop may be necessary. Zones 3 through cooler portions of 8.
PANICUM - See Grasses, Ornamental
PAPAVER oriental cultivars - Oriental Poppy
PLANTING: Set plants 15 to 18 inches apart, and in full sun. Plants root deeply, so cultivate the soil well - a well-drained, good garden soil is best. We recommend a winter mulch the first year. MAINTENANCE: Water during periods of drought. Seed pods should be removed after the flowers are spent, and foliage should be cut back as it turns brown in midsummer. In planting, remember that the Oriental poppy dies back in midsummer and their foliage reappears in the late summer. A companion plant such as Gypsophila can fill the gap. Plants dislike being disturbed. Zones 3-8.
x PARDANCANDA - Candy Lily
PLANTING: Set plants 12 inches apart. Choose a sunny location where the soil is well drained and on the light side. Plants will also tolerate light shade but bloom will not be as profuse. Cover the crowns with 1 inch of soil. MAINTENANCE: Plants may be divided as they become overcrowded. Remove flower stems once blooms have finished. In cooler regions where snow cover is not dependable, we recommend a winter mulch. Zones 5-10.
PARTHENOCISSUS species - Boston Ivy
PLANTING: Set plants 1 foot away from the support or wall (the plants will find their own way there). If planting more than one, space 21/2 to 5 feet apart, depending upon the speed of coverage desired. Well-drained garden soil and full sun are preferred, though Boston Ivy tolerates light shade. MAINTENANCE: Water well during periods of drought. Prune as needed in early spring to direct and control growth, cutting back weak or dead growth and trimming away from eaves, gutters, window casings and roofs. Zones 4-9.
PASSIFLORA - Passion Flower
PLANTING: Set out in sun and a deeply worked, moist, well drained sandy loam with humus added. For container growing, use a good grade of soilless potting mix. MAINTENANCE. Provide a sturdy trellis when grown on a support and prune heavily each year during fall or early spring to keep vine under control. Keep well watered during growing season . North of its hardiness range, bring plant indoors before first hard frost. Zones 8-11.
PEAR - See Prunus
PENNISETUM - See Grasses, Ornamental
PENSTEMON virgatus - Beard Tongue
PLANTING: Space 14 to 16 inches apart in slightly acidic, well drained soil in sun or light shade. Soils that are well drained in winter are particularly important. MAINTENANCE: Water during periods of drought. Remove flower stalks after plants finish blooming. Zones 4-8.
PEROVSKIA atriplicifolia - Russian or Azure Sage
PLANTING: Set plants 2 to 3 feet apart in full sun. A well-drained soil is essential. MAINTENANCE: Do not allow soil to dry out while plants are establishing themselves. In the North, prune in early spring, cutting back old stems to 12 to 18 inches, and, at the same time, thinning out any overcrowded shoots. In the South, little or no pruning is needed. Zones 5-9.
PERSEA - See Avocado
PHILADELPHUS species and cultivars - Mockorange
PLANTING: Spacing will depend on the ultimate height and spread of the particular species. Choose a location in sun or light shade (the latter being preferable in zones farther south). While widely tolerant of soil types, Philadelphus prefers a moisture-retentive but well-drained soil. Mulch at planting time. Plants will begin to bloom in about three years, once they’re established. MAINTENANCE: We recommend an annual application of mulch. Water well during periods of drought. A thorough pruning should be undertaken after flowering; remove old wood at this time to promote better growth habit and flower production. Add bonemeal or superphosphate in spring or fall to encourage flowering. Zones various.
PLANTING: Set out plants, 18 inches apart, in sun or light shade. Soil should be moisture retentive but well drained, deeply worked and enriched with organic matter - this is a heavy feeder. MAINTENANCE: Water during periods of drought and use a summer mulch to conserve moisture. Cutting back (deadheading) faded blooms will encourage a new crop of flowers later in the season. Zones 4-9.
PHLOX paniculata cultivars - Garden Phlox
PLANTING: Set plants 12 to 15 inches apart to allow for good air circulation. Choose a location in full sun or very light shade, and where the soil is moisture-retentive but well-drained, deeply worked and enriched with organic plant food - phlox are heavy feeders. MAINTENANCE: Water plants during periods of drought; a summer mulch is recommended to help conserve moisture. To promote vigorous growth, pinch out weaker shoots periodically during the growing season. Removal of spent flowers will prevent against seedlings not true to type. Divide every three years, discarding weaker shoots before replanting. At the end of each season, cut plants back to the ground, removing and discarding dead foliage. To control mildew naturally, avoid overhead watering and planting against moisture-retaining hedges, fences, or walls. If you must, spray foliage monthly with sulfur. Zones 3-9.
PLANTING: Space plants 12 to 15 inches apart in full sun to partial shade. In warmer climates, provide more shade. Performs best in an average garden soil that is well-drained and contains extra organic matter. MAINTENANCE: Water during periods of drought, and add a mulch of straw, pine needles, shredded bark, or chopped leaves to conserve moisture. Remove spent flowers after bloom. Zones 5-9.
PHLOX subulata - Moss or Mountain Pink
PLANTING: Set out plants 6 to 8 inches apart in full sun, preferably in a rather dry, well-drained soil of low fertility. While tolerant of a wide pH range, P. subulata prefers a neutral or slightly alkaline soil. MAINTENANCE: Shear back after flowering - this is essential to prevent the central portion of the clump dying out in a few years and presenting a rather shabby appearance. Zones 3-9.
PHYGELIUS - Cape Fuchsia
PLANTING: Set plants 12 to 18 inches apart in sun or light shade and in a light, sandy soil with good drainage and humus added. MAINTENANCE: Keep cultivated, watered and feed monthly with a balanced garden fertilizer. Pot up and overwinter in a protected area north of zone 6. Zone 6-10.
PHYLLITIS - See Ferns
PHYLLOSTACHYS nigra - Black Bamboo
PLANTING: Plant in full sun or partial shade (especially in hot areas) in a well drained soil that contains extra organic matter. MAINTENANCE: Water during periods of dry weather. The canes can be cut for use without any damage to the planting. Plants that spread out of bounds can be contained by placing barriers of sheet metal or heavy plastic or poured concerete 2 to 3 feet deep around them. Their spread can also be limited by periodically inserting a spade to its full depth around the clump, severing the rhizomes. Zones 6-9.
PHYSOCARPUS species and cultivars - Ninebark
PLANTING: Set plants 5 feet apart for hedges or up to 8 feet apart for single plantings. Performs best in full sun in northern areas but needs partial shade in warmer areas. Plant in any average soil (either slightly acidic or alkaline in nature) that is well drained. MAINTENANCE: To maintain a compact size, cut the entire shrub to the ground in late winter; plants treated in this manner will not flower. If a larger plant or flowers are desired, remove only 1/3 of the total number of older shoots immediately after flowers fade. Zones 2-7.
PHYSOSTEGIA virginiana and cultivars - False Dragonhead, Obedient Plant
PLANTING: Set plants 12 to 15 inches apart, in full sun. Some slight degree of light shade may be tolerated. A moisture-retentive, humusy soil will give best growth and flowers. MAINTENANCE: Water during periods of drought. It may be necessary to divide every three years or so to rejuvenate plants. This may be done in spring or fall. Zones 4-9.
PICEA species and cultivars
PLANTING: Spacing will depend on ultimate height and spread. Choose a location in full sun, where the soil is well-drained. MAINTENANCE: In general, spruces are low-maintenance plants, requiring only ample water and fertilizer. Little pruning should be necessary, except to shape as desired and encourage denser growth; pruning should be done in spring, once new growth is underway. We recommend a mulch year round. Zones 2-8.
PLANTING: Set out plants 4 to 6 feet apart, in a partially shaded location. Choose a moist, acid, well-drained soil, high in organic content, and a location sheltered from harsh winter winds. Although a member of the heath family, pieris is not as demanding of an acid soil as are many of its relatives, but will perform better in such soils. MAINTENANCE: Water during periods of drought. A mulch to conserve moisture will be beneficial. Prune to shape as desired - but do this after plants have flowered. Hot summer and drought are this plant’s major problems, so avoid these conditions and your Pieris will be virtually trouble free. Zones 5-9.
POLEMONIUM species - Jacob’s Ladder
PLANTING: Space plants 18 inches apart in a moisture retentive soil that is high in organic matter. Polemonium caeruleum performs well in full sun in the North but requires partial shade in warmer Southern areas. Polemonium reptans prefers partial shade in all areas. MAINTENANCE: Water regularly during dry periods. A mulch of pine needles, straw, shredded bark or chopped leaves will conserve soil moisture. Divide plants every 3 to 4 years as needed. Zones 3-7.
POLYGONUM aubertii - Silvelace or Fleece Vine
PLANTING: Plant in a sunny location, setting plants 10 feet apart if more than one is used. A well-drained soil, preferably of rather sandy texture. MAINTENANCE: Prune very early in the spring before new growth begins, cutting back some branches and thinning shoots, removing dead and weak wood. Pinching back tips during the growing season will promote denser lateral growth. Zones 4-9.
PONCIRUS - Bitter Orange
PLANTING: This plant grows best in full and in a moist but well drained soil that is somewhat acidic. Does not do well in alkaline or sandy soils. MAINTENANCE: Protect from cold drying winds. Prune immediately after flowering, if needed. Zones 5-9.
POTENTILLA species and cultivars - Cinquefoil
PLANTING: Set plants for use as a hedge or for massed effect 2 feet apart. (Dwarf varieties should be spaced closer together for quick ground coverage.) Choose a location in full sun or light shade, remembering that more sun encourages a more vigorous blooming season. A rich, well-drained soil will suit them very well. MAINTENANCE: Water well during periods of drought. We recommend, in addition, a summer mulch to help conserve moisture. An application of balanced fertilizer is a good idea. Shrubby types should be pruned to remove dead wood after spring growth commences; perennials may be divided as needed. Otherwise, no special care is required. Zones various.
PRIMULA cultivars - Primrose
PLANTING: Set plants 8 to 12 inches apart in filtered shade in a rich, highly organic soil. Primroses thrive best in a cool environment and sheltered against wind. They do poorly wheresummers are hot. MAINTENANCE: Keep soil moist, watering during periods of drought. A mulch will help conserve moisture during the growing season and will discourage heaving during winter. Divide in early fall every 3 to 4 years to rejuvenate, when necessary. P. sieboldii usually goes dormant in the summer, so be sure not to disturb them while they are dormant. Zones various.
PRUNUS species and cultivars - Flowering Cherries, Plums
PLANTING: If planting more than one tree, space according to ultimate height. Choose a location in full sun. While adaptable to soils, they prefer good drainage and will do well if some lime is added to the soil. Staking is advisable the first year, particularly if plant will be exposed to winds. MAINTENANCE: Prune as desired after flowering to correct structural defects and to open the center to sunlight. (This genus is vulnerable to canker and blight, so prunings should be destroyed.) A regular spraying regimen, along with sprayings to protect against scale and borers, is recommended, as is a summer mulch. Zones various.
PRUNUS persica - Peach
PLANTING: Space plants according to ultimate width. Choose a location in full sun. While adaptable to different soils, Peach trees prefer good drainage. Staking is advisable the first year. MAINTENANCE: Cut back newly planted trees to 30 inches in height, just above a lateral branch or bud. Prune while dormant to correct structural defects and to open the center to sunlight. Contact your local State Extension Service for a regular spraying regimen for insects and disease problems. Zones 5-8.
PUNICA granatum - Pomegranate
PLANTING: Plants are tolerant of a wide range of soils from sandy to heavy, poor to fertile, acid to alkaline, as long as the soil drains well. However, they perform best in a good, moisture retentive, well-drained soil. Full sun will give best flowering, although they grow quite well in partial shade. MAINTENANCE: Water during periods of drought. Pruning, while seldom needed, should be done in late winter. Plants will grow without any supplemental fertilizing in all but poor soils. Nevertheless, they will respond well to fertilizer which can be applied in early spring and again every 6 weeks. The fruit, which is actually a berry, follows the flowers and changes from yellow to a yellow-red as it matures in September and October. Zones 7-10.
PYRACANTHA cultivars - Firethorn
PLANTING: Space plants to allow for ultimate growth. Choose a sunny or partly shaded location, and a soil that has been enriched with organic matter. (A pH range from 5.5 to 7.0 is fine). A warm location, with shelter from drying winter winds, is ideal. MAINTENANCE: Pyracanthas are, in general, vulnerable to fireblight and scab. Our cultivars have been chosen for their resistance to these problems; even so, we recommend spraying several time a growing season to control scab. For espaliering, plant with one or more branches close to the wall to be covered. Prune off all growth that does not grow close to, or align with, the wall. Fasten the branches retained to the wall in several places, and continue to affix them as they grow. Only such subsequent growth as conforms to the form desired should be allowed to remain; prunings should be destroyed. For other uses, prune as desired to shape. Zones 6-10.
PYRETHRUM - See Chrysanthemum coccineus