There are no major problems to be solved when raising sweet peas. Once they are planted out, sweet peas are largely amenable to different plant rearing techniques and the plants are not very demanding. However, experience is necessary when attempting to grow sweet peas to plant exhibition standards. When growing sweet peas for exhibition purposes, the grower will benefit from following good crop growing techniques and being aware of the distinct foibles of sweet pea plants and knowing how to overcome them. At the same time, where the majority of gardeners are concerned, following some simple techniques will assure good garden performance, a goal which is attainable, by paying attention to a few simple requirements. Sweet peas of good quality can be grown by considering the requirements of the plants in the same manner in which the requirements of other plants in the garden are fulfilled.
The best growth of sweet peas occurs in areas with good sunshine. Wild sweet pea varieties also tend to grow out in the open areas in the wild and the plants grow best in open and sunny sites in the garden. A light shade can also be beneficial to the growth of sweet peas, a critical difference exists between the shade of tall trees - under which growth is poor - and the shade obtained from the side of a fence or wall, that can prove advantageous to the growth of the sweet pea plant. Growing sweet peas under the shade of tall trees is a recipe for disaster; good growth is simply not possible as there is just not sufficient light for healthy growth of seedlings. However, slight shade can benefit sweet peas, especially if they are grown in a site along a wall or fence with good exposure to the skies but upon which the sunlight is rarely direct - such sites are ideal for growing sweet peas. Growing sweet peas at sites without direct sunlight can in fact benefit the plants, many scarlet and orange varieties tend to retain their color well and almost all other varieties of sweet pea will hold their flowers for a longer duration if they are grown out of the direct scorching effect of strong sunlight.
All types of soils can be used to grow sweet peas, however, when growing sweet peas in soils heavy with clay and gravel, the addition of organic matter may be necessary to improve the growth characteristics of the plants. The growth of wild sweet peas and the other Lathyrus species in the wild begins to stop late in the spring and early summer, when temperature and light intensity go up. However, the aim of most gardeners is to keep the plants growing right through this period well into the summer. To achieve this, the plants in the garden will require a constant water supply and sufficient nutrients to prevent them from slowing down on growth for as long as possible. The solution to maintaining these plants in prime condition for as long as possible lies in the careful use of organic matter, the capacity of the roots to grow deeply into the soil is also an additional factor in good growth of plants. The addition of organic matter to the soil is to allow the soil to hold more moisture, when this organic matter is added in conjunction with organic or inorganic fertilizer, the plants are provided with all essential nutrients required for them to grow well beyond the spring. The main idea behind the addition of organic matter to the soil is to ensure that sufficient organic matter occurs at a depth in the soil from where the roots can use it for nutrients; when this is combined with additional watering and nutrient feeding when necessary - good and continual growth is assured. When this technique is followed, the sweet peas grown will give flowers with continuity of color and appearance well into the summer; rather than a single dramatic burst of blooming flowers followed by a sad and slow decline in the spring.
The first step before planting sweet peas is to go about digging a trench approximately 30cm ( twelve inches across in width), the trench must be dug in such a way that the line of the netting runs along the middle of the excavated ground. The depth of the trench should match the length of the digging spade employed for the purpose. The bottom of the trench must be turned over with a fork to the depth of the digging fork so as to loosen the soil and spread a layer 7.5cm thick ( three inches) of organic matter. The organic material used for the purpose can be varied, rotted compost or horse manure, composted bark or a planting mixture sourced from the garden centre can all be used; the organic matter needs to be fine and friable and does not have to consist of any particular mixture. The organic matter used can be forked into the bottom of the trench thoroughly and must be treaded into the soil to eliminate any air pockets formed at the bottom. The trench can also be partially refilled with soil, to this can be added another 5cm - 7.5cm of compost (two to three inches thick.) This can be forked into the upper layer of soil. The composted soil must also be treaded out, so as to leave the trench 2.5cm - 5cm thick and (an inch or two) lying just below the surrounding level of soil. The same approach and technique can be utilized when planting of the seeds is carried out on a circular wigwam of canes ;digging a round hole with a circumference bigger than the diameter of the intended wigwam is the first step, a depression also needs to be left in the middle as before. Where the intention is to plant seeds along a narrow vertical cylinder of wire to be used as support, the same procedure can be followed, however, the area must be scaled down to match the area of the site for growing the plant. The preparation of the soil for subsequent plantation of the seeds can be carried out at any convenient time during the fall, the winter or the early spring. There is really no ideal time for the preparation of the soil and it just needs to be made ready for sowing or planting in the spring of the following year.
The Mediterranean region is the likely place of origin for the sweet peas and other forms of annual Lathyrus species. This region has mild and damp winters alternating with hot and dry summers - which are ideal climatic regimes for the plants. However, sweet peas and other annuals of the genus Lathyrus can also overcome light frosts and easily tolerate some summer heat if they are kept sufficiently moist during such times; however, these plants do not tend to grow well in areas that have high humidity in the summer time.
Planting and growing sweet peas does not involve any special mystery and the sweet pea is one of the least demanding of garden plants in many respects. There are some factors that can aid growth of sweet peas; raking in some fertilizer or a handful of bone-meal into the soil - at about 60 gm / 2 ounces per sq meter/yard can really boost growth of the plants. Other measures can include watering the plants in their pots with a liquid feed the day before planting takes place, this procedure will encourage them to settle down quickly into the soil. Once the plants come out, they can be carefully knocked out of their pots and planted into the soil. Digging the hole must be given priority when a whole pot full of seedlings is being planted all together at one time. If planting of the seedlings is carried out under the assumption that the soil is already well prepared and ready to take plants, simply plant the seedlings into the soil in the normal way and leave a slight depression in the soil afterwards to allow the plants room to grow. Where the planting requires the splitting of the root ball and the seedlings to be planted out individually - it is best to knock the seedlings gently out of the pot and to then pull apart the individual plants using the fingers as gently as possible to avoid damage. If this procedure is followed, a few roots may break; however, the plants will recover rapidly from this mechanical injury and grow well giving a good bloom. It is also best to leave as much compost as possible around the roots to give good growth. When planting, a trowel should be used to dig the soil, then the plant can be slid into the hole, firming the soil around the plant gently leaves air spaces and ensures good growth. It is best to leave the plant laying just a little lower in the soil than it was lying in the compost filled pot. Once rooted in the soil, the seedlings must be watered thoroughly, with some liquid feed included in the water; they can then be mulched for good measure. This can be accomplished by using any weed free organic matter; for this reason, the use of garden compost is unsuitable unless the person is a genius at composting and can ensure that the compost heap heats up well before it is used. The contents of old growing bags can be used for this purpose, once it has been carefully broken up; composted bark or other bagged mulch bought from the local garden centre can also be employed to bring the same results.
If the sweet peas are to be grown mainly to get them to serve the purpose of natural "bushes" within the garden - the initial aim must be to encourage the shoots to climb along a gradient - a cane pole or netting - rather than to allow them to meander off across the garden haphazardly. Where the sweet pea plants are to be grown on canes without any additional netting to hold them down, the use of a little brushwood around the base of the plant will provide initial support or the shoots can be tied to the canes using some soft twine. The tips of the shoot and the tendrils of the plant begin to move as the sweet pea plants grow up, these structures search for support on which to cling or grow along. Giving the plants a little help during this stage is often advisable to get maximum growth out of the plants. The shoots and the tendrils can be tucked behind wired mesh to help them grip the cane or netting in a much better way. These soft young growth must be handled with care as they are quite soft and fragile and the gardener must stay aware of doing damage and handle them carefully at all times. Once the sweet pea plants have begun to grow up, the growth of any wayward shoots may require tucking down or tying in place - the procedure followed will depend on the training method utilized by individual gardeners.
If the plants are prevented from setting seeds, it will ensure that they stay in full bloom for as long as possible well past their normal season. Where the sweet pea flowers are picked off on a regular basis for cutting, this step will not be necessary. However, if this is not the case, and the gardener wants to take a holiday during the flowering season, he or she better ask a neighbor to keep picking them so that flowers are still opening when he or she returns home. Dead-heading is also essential when the plants are grown for display purposes. Short cuts are not involved in any stage of the process and care must be taken at all steps. For best results, all flowers must be snipped off at the area where they join the stem when they are being plucked. Occasionally, gardeners will come across fading flowers that drop off without setting seed in time; these must be snipped off the bare stems anyway to ensure the health of plants.
Ideally, the sweet peas will grow best with lots of water as these plants love water. This holds true only if the soil is sufficiently well drained at all times to avoid water logging - which can kill the plants. Sufficient water in the soil with the absence of water logging will prolong the floral bloom, and lead to an increase in the number of flowers borne per stem. A good supply of water in the soil also ensures that individual flowers last as long as possible and will generally improve the health of the plant. One of the best ways to ensure a sufficiency of water around the plants is to leave a slight depression in the soil to permit it to hold water from a can or hosepipe. This can be poured in the depression and water can be kept in the required area around the plant in this way. One other alternative for growing clumps of sweet peas in shrubs or trained on narrow supports is to sink a 12.5cm-15cm floral pot (a five to six inch flower pot) alongside the plant for holding water. The pot buried alongside the plant can then be filled with water at regular intervals and the water given to this pot will seep out through the drainage holes directly down to the roots of the nearby plant without the risk of it running all over the border and logging up. A seep hose or a rubber hose with micro perforations are ideal implements for giving water to large towers and wigwams - the rubber hose with the micro perforations allows the water to gradually and constantly ooze out, giving the plant just sufficient water at any time. In this way, the problem of water logging over a large area is completely nullified. The hose can be laid along the row, or around the tower or wigwam, before any mulching is carried out. Once the hose is connected to the mains, a slow and steady trickle of water will seep under the mulch and soak its way down straight into the soil - this is the ideal spot and where water is most needed by plants. Utilizing this technique well will result in minimum wastage of water through evaporation or wind drift. The method will also supply water directly to the roots where it is required and easily accessible to the growing plants.
Liquid feeding during the season can be completely avoided if the preparation has been thorough and well executed. A liquid feed that is low in nitrogen content is ideal for this purpose, and can be applied generously to ensure that it reaches down to the full depth of the roots of the plants. The liquid feeding can be carried out as required based on the inherent fertility of the soil used for growing the plants, weekly or bi-weekly application of the feed should be sufficient in most cases. Over the years, many specific types of sweet pea feeds have been made available. And new types of feed combinations have periodically appeared over the years. These feeds can either be used for raking in as dry feeds or for diluting in water to feed the plants. If such feeds are available at the local garden store, they should be preferred over the other types.
The cordon technique is used mainly by serious plant exhibitors and professional gardening competitors. The method is used to a lesser extent, by many gardeners who want high quality cut flowers. The technique depends on the restriction of the growth of each sweet pea plant to a single shoot; the result is the production of larger flowers on very much longer stems - which are ideal as show flowers. This arrangement also improves the placement of the individual flowers along the stem as the fact that the plants have more light and are less tangled works to ensure this outcome. Many of the more experienced plant exhibitors have also developed their own sophisticated variants of these techniques of growing sweet pea plants. If the cordon technique is utilized, sowing in the fall is almost an essential requirement to achieve the proper bloom. An important factor for this is that the plants have the time to produce a much more extensive root system with robust growth and that this will result in the increased vigor of the plants being grown. One useful alternative to the technique is to sow seeds late in the winter. However, leaving the sowing until the spring season will not allow the sweet pea plants sufficient time for the development of an extensive and well grounded root system in time to support the extensive flowering desired of the plants. Once the trench for growing the plants has been completed, the supports for plants can be put in place during the winter. The technique involves initially, erecting a stout vertical post at each end of the row along the trench. The post can be 2.4m (8 feet) or 10cm x 10cm (4in x 4 inch) posts. These can be sunk about 60cm (2 feet) into the ground ideally to provide a firm support. The next step is to fix a 2 ft (60cm) long piece, or a 10cm x 5cm (4in x 2in) piece across the top of each post on the outer end of the structure. The next step is to run a length of galvanized wire from both ends of the crosspiece to their counterparts at the other end of the row and then to tighten this set up till it is secured. The main purpose of this wire is to support the canes to each individual plant to be trained and grown along. This is to be followed by the insertion of a 2.4m (8ft) length of bamboo cane vertically into the soil at every 20cm - 23cm (8-9 inches) interval along each side and then to tie the top of the structure to the wire with twine. The completed structure should result in a double row of vertical canes, which is securely supported and used for training sweet peas. When the spring comes, one plant can be planted alongside each cane in March or early April; approximately 5cm (2 inches) to one side of the plant. Use liquid feed to water in the soil in which the plants are being grown. Once the sweet pea plants have been planted, all but one of the shoots should be removed from each single plant, however, this must not be carried out at once as the energy produced by the foliage on three or four shoots is valuable for the growth of the plant. All the shoots excepting one should be snipped off late in the month of April or early in May. When sniping off shoots, it is not necessary to choose to keep the tallest shoot. Priority must be given to the most robust shoot as this is usually the best and most suitable shoot, even if it is shorter than the other shoots. The remaining shoot, which should be about 23cm - 30cm (9-12in high) can be tied using twine, wire rings, sweet pea support clips or by a taping machine. Once the shoots start to grow and elongate, they need to be tied in again so that they never have to swing to the side or droop over the body of the plant. Ideally, one should tie at every leaf joint along the stem to get the best results possible. The shoot chosen for the purpose will soon start to give off side shoots as part of its growth process. The new shoots must be snipped off, and the tendrils too should be removed soon so that only the main shoot and its foliage remains tied to the cane to allow for good growth of the plant. The sweet pea plants will begin to bear flowers once the plants are about 60cm - 90cm (2-3 feet in height); these early flowers will not be the top-quality blooms but can be cut and used for display at home; these early flowers must not be left on the plants. Something has to be done to accommodate the burgeoning growth, as the plants approach the tops of their canes once growth has truly begun. What is actually happening is that, the plants are untied from their canes, the stems are then to be laid on the ground along the row for a distance of 60cm (2 feet), the plants must then be tied in again to a new cane and then guided to grow up the long axis of the cane. The training of plant growth in this manner must be carried out in a careful and organized manner, it is very important to avoid stepping on the shoots during the process. Extra canes will also be required across the ends of the row at this stage of growth. If this is carried out successfully, the stems will now have the extra cane height in which to grow and bloom.