Cufea (Cuphea) fiery red, reproduction and care, species and hybrids

New plant for indoor and ornamental floriculture

According to the horoscope, the zodiac sign of Libra (September 23 - October 23) is accompanied by plants: large-crested pineapple, Japanese azalea (white), Chinese rose, Japanese fatsia, chrysanthemum, wavy-leaved krosandra, capsicum, codiaum, truncated zygocactus, heliotrope hybrid and red kufeya fire ...

Kufeya can be attributed to the number of indoor flowering plants that are little known to most amateur flower growers, but it is worth paying more attention to it. The name of the genus - Cuphea (family Verbeinikovye) - is rather prosaic, it was assigned because of the shape of slightly curved fruits: "kyphos" is translated from Greek as "bent", "crooked". The genus includes, according to various sources, from 200 to 250 species of herbaceous perennials, semi-shrubs and shrubs, common in the temperate, subtropical and tropical regions of Central and South America.

Among them there are annuals more than a meter high. It also includes a group of low-growing dwarf shrubs and shrubs, interesting due to the numerous small bright flowers and long flowering.

They are useful for open field growers, who especially often use plants of some types of kufei in more southern latitudes for growing in containers. This is how the following kufeis contain - creeping (C. procumbens), lavea (C. llaavea), cinnabar red (C. miniata), purple (C. x purpurea) and lanceolate (C. lanceolata).

For growing in the premises of our zone, both the listed species and "home" types of kufei are quite suitable - fiery red (C. ignea or C. platycentra), hyssopolis (C. hyssopifolia) and microleaf (C. micropetala)... And it is the last group of species that is usually found on sale. Of course, a pot of kufei seedlings can be taken out to our garden after the period of spring frosts, in order to keep there until the cold weather.

Due to the high light-loving nature, it is better to place the kufei indoors where there is a lot of bright light, but in the hottest summer hours there should be mandatory shading from direct sunlight. It grows well on windows facing west and east. For this very thermophilic plant, it is desirable to provide a temperature of 20 ... 25 ° C in summer, and 15 ... 18 ° C in winter.

Although this plant is considered to be quite drought tolerant, it is not recommended to abuse this quality. Abundant during active growing season - from April to August - watering is gradually reduced by autumn, and in winter it should be extremely moderate, but complete overdrying of the soil substrate is not allowed.

Kufeya normally tolerates low air humidity, however, for its normal growing season, the florist should still spray the plant with warm water. During spring and summer, it is fed every two weeks with a weak solution of mineral fertilizers intended for flowering indoor plants, which ensures abundant flowering of kufei.

Experts advise to carry out an annual transplant of kufei in the spring. For this purpose, a fertile soil is needed, consisting of leafy, sod, peat and humus soil, river sand (in a ratio of 1: 1: 1: 1: 0.5). Be sure to arrange a good drainage layer at the bottom of the container in the form of fragments of pots.

Kufa is propagated by semi-lignified stem cuttings and seeds. There are two most favorable periods for this - spring and late summer. Cuttings root quite well if a number of conditions are met. If planted in fertile soil, then it should be well moistened, but without excess water (temperature 22 ... 26 ° C). If the cuttings are placed in water (20 ... 22 ° C), then its layer should not exceed 1.5-2 cm. This is constantly monitored and water is added to the desired level as it evaporates.

With seed propagation, kufeya is usually grown through seedlings. Its greenish-brown seeds (up to 3 mm in diameter) are light (about 300 pcs per 1 g), very similar to curved discs. They are usually sown in late March - early April (the second term is more suitable for open ground). It takes no more than 7-10 days for seedlings to appear. It must be borne in mind that during germination, the seeds secrete a sticky substance. Therefore, if they are located too close to each other, then a lump is formed, resembling a cake, from which a single seed is extremely difficult to extract.

Seeds of kufei are characterized by high light sensitivity: they grow faster in the light, therefore they are not embedded in the soil (you just need to slightly press into it, and cover with glass on top). The optimum temperature for their germination is 20 ... 22 ° C. Good illumination of seedlings is necessary: ​​with a lack of light, it stretches very quickly.

Young kufei plants dive, as a rule, at a slight slope into deep containers, which are installed in a sufficiently illuminated place so that they do not stretch too much if there is little light. Otherwise, you will have to pour soil under the cotyledon leaves later so that the long seedlings do not fall. If the plants are planned to be transferred to open ground, then for normal life, the seedlings should be pre-hardened. When the danger of spring frosts has passed, young kufei plants are placed in open ground (late May - early June), where light nutritious or moderately fertile soils are chosen for them (seedlings are planted a little deeper than they were in picking containers).

For this purpose, there should be a well-lit place in the garden, in extreme cases, it can be planted in a slightly shaded one. But it is categorically not recommended to plant young plants in damp corners of the site, where there is no air movement. When planting, the distance between them should be at least 30-35 cm. At this time, watering of seedlings in dry weather is especially important. Care consists mainly in the timely weeding of the weeds. Kufeya blooms in late June - early July and continues to bloom until frost. It should be borne in mind that the vegetative mass of kufei grows rapidly, therefore, pinching and pruning is carried out to regulate branching. Some growers keep pots of kufei in the outbuildings of country houses - on light terraces. These extraordinarily beautiful flowering plants look great thanks to their hanging stems on the support walls in hanging planters and baskets.

The most popular among indoor species is considered to be fiery red kufeya (origin - Mexico and Jamaica). This is a shrub or herbaceous perennial with a height of 25 to 40 cm (depending on how they want to get it - in the form of an erect bush or an ampelous plant). Its shoots have opposite, oblong or ovate-lanceolate pointed leaves up to 6 cm long, 2 cm wide.

Single flowers (2-3 cm long) are located on short pedicels in the axils of the leaves, they are almost without petals, and are very unusual in color. The tubular perianth (calyx) is bright red with a small dark purple limb with white ends and a black pharynx. There is a short swelling ("spur") at the base of the perianth.

For the obvious resemblance of flowers to a smoldering cigarette, as if covered with ash, in England this kufeya acquired the popular name cigar plant (cigarette plant). Recently, this species has received the Coan form of two colors - the usual red-orange and white. If the fiery red kufeya is grown as a balcony culture, then too elongated shoots are only slightly shortened.

Fiery red kufeya is characterized by very intensive growth and active branching. If you create optimal conditions for her and ignore the pinching, then she will give shoots so long that they will fall to the ground under their weight, turning into a ground cover plant, or hang out of the container, like an ampelous culture. The flowering of kufei is long-lasting. Blooms in mid-July.

Propagated by seeds. According to experts, 1 g contains 700-750 seeds. Although under the conditions of good cultivation, kufei gives fiery red seeds, it is not easy to collect them, since as it ripens, the ripe fruit cracks, and they fly in different directions.

When exposed to favorable soil conditions, such seeds germinate and give seedlings. You can, of course, close the boxes with a light piece of gauze to hold the jumping seeds. Then these harvested or purchased seeds are sown. Experienced growers assure that plants obtained from seeds are more beautiful. Fire-red kufeya can also be propagated by cuttings: green apical cuttings give roots in water after 10-15 days, and in summer, in warm weather, even faster.

This type of "home" kufei also looks great in the open ground of our zone (in separate flower beds, in the form of a line along the paths or in a group on an illuminated alpine hill). It goes well with other summer outdoor (container and balcony) plants, especially if it is in the foreground.

Shoots lying on the ground take root, so they can be planted out when the flower rejuvenates. Therefore, with an autumn transplant, only small bushes should be taken from the mother bush. In general, this species is usually cultivated as an annual plant, grown on balconies and terraces. But you can leave it to overwinter and make it bloom for next year. Then in the fall, at the end of flowering, watering is reduced, and for winter maintenance, a cool (10 ° C) light room is found for the plant; watering - every 10 days. In March, this plant is transferred to a warmer room.

Cufea hyssopolis is native to Mexico and Guatemala. This is a shrub or semi-shrub (35-50 cm high) with numerous profusely branching shoots, with narrow opposite, sessile or short-petiolate leaves (up to 2.5 cm long, 0.4 cm wide) of a dark green color, lanceolate, whole-edged.

Small flowers (about 1 cm in diameter) are numerous and sit singly in the leaf axils. The calyx is tubular, widened upward, short-toothed. The corolla is separate, with six identical petals (according to experts, a characteristic atypical for a kufei), lilac-pink in color. The petals at the base are fused with the calyx.

The shoots of kufei hyssopolis are literally covered with these flowers, but they are sterile, so there are no seeds. The known form of kufei hyssopolis is white-flowered (Alba). This species may be of interest to amateur flower growers cultivating plants of the "bonsai" type. In the lower part of the plant, the shoots are lignified, so it quickly turns into a dwarf tree.

Hyssopolis kufea is propagated by well-ripened green cuttings (5-10 cm long), which root well in wet sand, even in water they form a good root system. Let me remind you that the leaves are carefully pinched off from the bottom of the petioles so that they do not rot in the water. Hyssopolis kufea requires very careful shaping of the crown. Due to its strong bushiness, the plant of this species can be shaped like a ball or a pyramid. During the summer, it is possible to maintain the shape of the kufei only by periodically pinching the ends of the shoots.

Micro-petal kufeya is a shrub with a height (30-40 cm) with small narrow leaves, very similar to the previous species. Small flowers appear one after another, but not in the axils of the leaves, but above, above them. The top of the flower cups is yellow, but at the base they are scarlet, the throat is greenish, the stamens are red. The petals (there are six of them) are so tiny that they are almost invisible due to the teeth of the calyx. Although kufeya is micro-petal and produces many seeds, it is preferable to propagate it by cuttings.

Other types are much less common among amateurs. An annual species - lanceolate kufeya - is unusually beautiful. This is a fast-growing plant (70-90 cm high), with purple, strongly pubescent soft hairs, stems similar to whips with lanceolate light green leaves. He has dark purple tubular flowers (2-3 cm in size), collected in one-sided rare inflorescences-ears. Lanceolate kufea blooms from the end of July. Propagated by seeds (200-250 seeds per 1 g).

Kufeya prostrate - low (about 40 cm) annual plants with strongly branching stems located on the ground with dark green leaves. She has lilac flowers (less often white or purple). Bloom from mid-July. Propagated by seeds (300-350 seeds per 1 g).

Very popular in European countries and so far extremely rare in our country kufeya Blazing bonfire (C. miniata) is an interspecific hybrid of kufei lavei and prostrate, which received its own name. These are ampelous annual bushes (25-30 cm high) with magnificent cascades of their flowers, with which they delight flower growers all summer. As a rule, this kufeya is placed in elegant baskets and hanging pots. Its most popular variant is called Firefly (C. lavea var. Miniata Firefly), which is distinguished by its fiery red flowers. It looks good in compositions with other flower crops that have dark red flowers.

Kufeya as an ornamental plant is still very "young" in comparison with other flower crops: breeders paid attention to it only 20-30 years ago. Some annual types of kufei in their homeland have found application in perfumery. They are grown to obtain seeds from which fatty acids are squeezed out (for example, laurel, which is necessary for the manufacture of shampoos).

To unfavorable conditions (draft, prolonged drying of the soil, cramped pot, getting under frost), kufeya can react by dropping foliage. Depending on the cause of this phenomenon, the plant is removed from the draft, dry shoots are cut to half the height of the plant, transplanted into a more spacious container, and fed. If you carried out this procedure on time, the plant will give young leaves after 2-3 weeks. Of indoor pests with high dry air, a spider mite may appear on the leaves. When placing kufei in damp shaded corners of the garden, powdery mildew may appear on the leaves.

Alexander Lazarev, candidate of biological sciences

Diastia Barbera

drained, neutral, sandy loam

direct sunlight, partial shade, scattered sunlight

Low, up to 30 cm, diastia of Barbera (Diascia barberae) attracts attention with its pink flowers, shaped like the shells of small molluscs.

This cold-hardy and moisture-loving plant, native to South Africa, is suitable for both light and slightly shaded balconies. Grows well as a container crop. Looks great in pots and garden vases. In a flower garden it can be used as a border, although this plant looks spectacular in vertical gardening.

Despite being a perennial, the new F1 hybrids allow diastia to be grown from seed as an annual. A hybrid works well for balcony boxes and hanging baskets. F1 'Asca' - a compact dense bush, uniform in height and width - 25-30 cm. The plant forms a "hat" of medium-sized, 1.5 cm in diameter, delicate flowers of white-pink, pink and apricot colors. Resistant to heat and continuous rain.

Diastia seeds are not large (1 g 4000 pieces), therefore, when sowing, they are only slightly sprinkled with substrate or vermiculite. The soil should be loose, moist, well-drained and neutral. At a temperature of 16-18 ° C, seedlings appear in about two weeks. When sowing seeds in open ground in May, diastia blooms in June. Seedling growing allows you to get flowering even earlier. Seeds are sown for seedlings in February-March. During growth, the seedlings are pinched several times so that they bush better.

Flowering lasts 1-1.5 months. To prolong it, the faded stems are cut at a height of 5-7 centimeters, if after that the plant is provided with good watering and nutritious feeding, the stems will quickly grow back and bloom again. Re-flowering can last until September, although it will not be as abundant.Until this moment, you need to be careful with fertilizing, since an excess of organic matter in the soil stimulates the growth of shoots, but weakens flowering.


The plant is resistant to heat and prolonged rainfall.

Prefers a warm, sunny place and loose, moist, well-drained and neutral soil, such as light sandy loam.

To prolong flowering, the faded stems are cut at a height of 5-7 cm.

Features of kufei of different types

Leaves are medium-sized, lanceolate, numerous, oppositely sitting, up to 2.5 cm long. This plant is most widespread in America (its central and southern parts), where it occurs in the form of shrubs or semi-shrubs.

Abundant and long flowering is characteristic of kufei, which begins in the first month of spring and pleases the eye until mid-autumn. Each bud lasts only a few days, but is quickly replaced by another. During this period, small shrubs of this plant acquire an incredibly beautiful appearance.

Due to their decorative appearance and long flowering period, they are often used in garden flower arrangements, planted in groups in voluminous vases or containers.

Look not the flowers of the kufei in the photo, with proper care it is possible to achieve good growing results and create interesting compositions with their help:

In addition to their aesthetic beauty, some types of kufei are also valued for the fact that it is a material for obtaining laurel acid, which is successfully used in the chemical industry.

Even despite the fact that gardeners became interested in this plant relatively recently, more than 200 of its species are already known. Over the past 12 years, about 10 new varieties of kufei have been bred.

Consider the distinctive features of some species and varieties.

Kufea hyssopolis (C. hyssopifolia) - a bush or semi-bush plant, the height of which can reach half a meter. The foliage is located on small petioles, their length is 2.5 cm, and their width is 0.5 cm. The form is lanceolate, dark green in color. It blooms with medium-sized buds (no more than 1 cm in diameter), they are solitary with axils. Their color, depending on the variety, can be snow-white, lilac or pink. This species is distinguished by increased bushiness, but it is rather small in size, therefore it can be used as a bonsai. Allocate varieties:

Hyssopolis kufea "Honey Hutter" (C. hyssopifolia "Mad Hatter").

Caféa Hyssopolis "Star White" (C. hyssopifolia "Star White").

Kufeya fiery red (S. ignea) - another type of flower called kufeya. It grows like a shrub, and reaches a height of no more than 40 cm. It differs from the hyssopolis species in the shape of its foliage. It is rounded, ovoid, 6 cm long and 2 cm wide, and is dark green in color. The buds are single, axillary, large enough, red in color.

Micro-petal view of kufei grows as a shrub plant no more than 30-40 cm in height. This variety has a great similarity in its greens with hyssopolis: it is small and narrow. The flowers of this type of kufei are medium-sized, located in the axils of the leaves and appear as the plant grows. Their color is yellowish, and closer to the core - scarlet, the throat is slightly greenish. The flowers have bright scarlet stamens.

Look at the kufei bush in the photo, and below read the description of the features of caring for these plants:

This species also has another name - false Mexican heather. This sprawling shrub reaches a height of 60 cm. The stems are flat, with branches resembling a fern. The leaves are small, oblong. It blooms very luxuriantly and for a long time, almost throughout the summer.

The flowers are star-shaped, small, numerous, with pronounced petals at the end of a yellow tube. They are sterile and do not produce seeds. But they have an enviable variety of colors: from purple to white.

The species is notable for its shade tolerance, but it blooms more magnificently in bright light, however, it does not tolerate direct sunlight.

The shoots of Kufei hyssopolis are characterized by rapid growth and lignification. Cuttings root easily. Once every few years, the bush is recommended to be rejuvenated by division. This species can also be grown in bonsai form.

Other types of "Kufei"

Subscribe and receive descriptions of new species and varieties in the "flowering (garden)" section by mail!

Planting a decorative lash

Ornamental legumes with early and medium-early ripening are planted with seeds in open soil. Bean cultivation begins with the onset of warm weather.

Landing dates

The sowing season begins with warming up the soil and the onset of steady heat. Cold nights will inhibit plant growth and development. The seeds begin to germinate at a ground temperature of more than 10 degrees, if the night temperature drops to 1 degree, then the seeds may not sprout at all.

In the central regions, grain is sown in mid-May, in the north - in early June, and in the south of the country, planting is done in April, after the 15th. The optimum temperature for beans is 19-24 degrees.

Beans decorative curly planting and care

For planting, you need a warm, light, loose earth, preferably without clay. If underground waters are located close to the surface of the earth, then they make an elevated bed. Planting directly into the ground does not require transplanting fragile seedlings, which can be damaged, broken or not adapted to the external environment when moved.

Sequence of planting seeds:

  • soak the grains for a day in warm water
  • transfer the seeds to a manganese solution for 25 minutes
  • lay out the fruits on a towel to dry out
  • make recesses in the ground 1.5 cm at a distance of 30 cm, between rows 40-50 cm, watered
  • put 2 grains in one hole
  • covered with a layer of earth, watered
  • mulch the ground with straw, sawdust, dry grass.

Soil temperature should be at least 13-14 degrees. A support is installed next to each hole, a fishing line, a rope is pulled so that the vine does not spread on the ground, but beautifully braids the support.




2 929 records


Magnolia is a tree with incredibly beautiful flowers that will decorate your garden, make it bright and expressive, filling it with an alluring vanilla-lemon scent. And do not be afraid of her possible capriciousness: Show in full. I will try to dispel all doubts and share the intricacies of growing and caring for magnolia.

A symbol of virgin purity in China, magnolia is held in high esteem in our country too. Its extraordinary beauty and delightful aroma have long been admired.

In the middle lane, it begins to bloom as early as April, when most of the trees are not even covered with leaves. Apparently, therefore, the huge flowers are surprising and delightful. Although magnolia is valued not only for its beauty. Its leaves, flowers, fruits and even bark contain essential oils - a unique antiseptic for hypertension, rheumatism and diseases of the digestive system.

Magnolia (named after the famous botanist P. Magnol) is one of the brightest representatives of the magnolia family, which has over 70 species. Its luxurious trees with a wide pyramidal or spherical crown can reach 5-8, or even 20 m in height. Depending on the variety, the flowers can be white, pink, purple, red, and even lilac. True, out of 120 varieties, only a few manage to grow in the middle lane (the rest are really capricious and simply will not survive our harsh winters): magnolia kobus, magnolia stellata and some of their hybrids. Later we will analyze them in more detail, but for now, let's discuss the nuances of growing this amazing plant.

Planting magnolia.
Before you start planting a magnolia, you need to choose the right seedling: it must have a closed root system.

Spring landing.

The landing site is determined in advance, given that magnolia:
prefers areas protected from winds and drafts
absolutely does not tolerate heavily limed soils: in them the roots hardly develop and may die. If the soil in your area is exactly like this, mix it with acidic peat, this will lower the pH.
grows poorly on heavy, waterlogged and sandy soils.

The best place for planting will be sunny, in the southern regions - a slightly shaded area with light fertile soil.

Regarding the timing of planting, most gardeners agree that it is better to plant magnolia in the fall, when young seedlings have already stopped growing, as if "falling into hibernation." Autumn planting should be done in mid-late October, when there are no severe frosts yet, and the unbearable heat is gone.

Opinions differed regarding the spring planting. Some gardeners believe that young magnolia saplings, like most trees, can be planted in the spring - in April. The latter insist that even small return frosts can cause irreparable harm to trees that have already begun to grow, after which rehabilitation will be long and, most likely, ineffective. To listen to such conflicting opinions or not is up to you. But think about whether the risk is justified: after all, a seedling correctly planted in the fall will almost 100% take root.

Having chosen a place, we begin to prepare the landing pit. Please note that the size of the hole should be three times the size of the root system of the seedling. Having taken out the required amount of soil, mix it with rotted compost. If the soil is too dense, add some sand. Having prepared the earthen mixture, we place the seedling in the planting hole, in no case deepening the root collar, and fill it with the mixture so that a small hole forms around the tree. Then we slightly compact the earth in the hole and water it well. As soon as the water is absorbed into the soil, we mulch the trunk circle with peat / sand or cover it with conifer bark.

Reproduction of magnolia.
Magnolia reproduces easily vegetatively: by grafting, layering and cuttings, but if you wish, you can try to grow this plant from seeds. Let's take a look at each of the options:

Magnolia reproduces easily vegetatively.

How to grow magnolia from seeds?
It is better to sow magnolia seeds immediately after picking the berries, in the fall, since it is rather difficult to keep them until spring. Since the seeds are covered with a very dense oily shell, they must first be scarified, that is, mechanically destroying the shell (filed or chopped). After scarification, the magnolia seeds are washed in a mild soap solution to remove the oily layer and rinsed in clean water. Having sown seeds to a depth of 3 cm in boxes with a universal substrate, they are removed to the cellar until spring.


Derbennikov family. Homeland - Mexico, Guatemala, island. Jamaica.

These are Mexican plants with a Greek name. The name, however, is quite prosaic. Kyphos translated as "bent, crooked". The fruits of the kufei are indeed slightly curved.

In Central and South America, there are up to 200 types of kufei.

Among them there are annuals, reaching almost a meter in height, there are undersized dwarf shrubs and shrubs. The latter are popular in Europe as ornamental plants.

Especially appreciated kufeya fiery red (C. ignea or C. platycentra), kufeya hyssopolis (C. hyssopyfolia) and kufeya micro-petal (C. micropetala)... Here, these species are better known to lovers of indoor plants.

They bloom starting in March, as soon as the sun shines brighter, and until October - when its light dims. Kufi bushes grow quite quickly, they must be regularly pinched, cut and transplanted, otherwise the decorativeness of plants is significantly reduced.

Abroad, this feature is successfully used, planting kufeis for the summer in large street vases and concrete containers together with different summer houses.

Annual species Cuphea at home they are grown to obtain seeds - a source of fatty acids, including laurel, which are indispensable in the production of shampoos. And how ornamental these plants are little known, and only in recent decades have breeders seriously taken up them.

Almost all species have flowers with six unequal petals - the top two are much larger than the other four. And those who like a riot of colors and large flowers are unlikely to see anything remarkable in them. Modest kufeis - for lovers of exoticism and meditation. Or for owners of cats and dogs: unceremonious pets cannot get through a bed with tall kufei - they are unlikely to like the numerous sticky shoots.

Kufea hyssopolis Cuphea recurvata - shrub or semi-shrub about 50 cm tall. Leaves are opposite, on short petioles, lanceolate, about 2.5 cm long and 0.5 cm wide, dark green in color. The flowers are axillary, small, up to 1 cm in diameter, solitary, lilac, pink or white. The plant is very bushy and compact in size, and therefore can be grown as a bonsai.
Cufea fiery red Cuphea ignea - a shrub about 40 cm tall. The leaves are opposite, on short petioles, ovate-lanceolate, about 6 cm long and 2 cm wide, dark green in color. The flowers are axillary, up to 3 cm in diameter, solitary, red in color with a purple limb.

Temperature: Kufeya is thermophilic, so in summer the temperature is around 20-25 ° C. In winter, the optimum is 15-18 ° C, minimum 12 ° C.

Lighting: Kufeya is photophilous. Requires bright light, shaded from direct sunlight only during the hottest hours of the summer.

Watering: In the summer, the kufeya is watered abundantly, in the fall the watering is reduced, and in the winter it is watered moderately, not allowing only the complete drying of the earthen coma.

Fertilizers: Regularly from April to August, they are fed with a solution of mineral fertilizers for flowering indoor plants. Top dressing is carried out after 2 weeks.

Air humidity: Kufeya rather stoically tolerates low air humidity, so only periodic spraying can be carried out.

Transfer: Annually in the spring. Soil - a mixture of 1 part leaf, 1 part turf, 1 part peat, 1 part humus and 1/2 part river sand. Good drainage is a must.

Reproduction: In spring or late summer, semi-lignified cuttings, as well as seeds.

Watch the video: This NEW POKEMON GAME is INCREDIBLE! Pokemon XENOVERSE Nuzlocke!

Previous Article

Information About Bog Rosemary

Next Article

What fertilizers need to be applied when planting potatoes