Tips on growing of gladioli
First, you should know well eleven rules without which it will be difficult to succeed in growing of gladioli and caring for them:
- do not grow gladioli in one place for more than two years, transplant them to another place in three years, observing the golden rule of the florist – a crop rotation;
- when replanting gladioli, choose a site with another soil composition. For example, if gladioli initially grew in sandy loam soil, transplant them into light sandy soil in a couple of years;
- buy a planting material adapted to your climate zone, since gladioli do not like to get out of a warm climate into a cool and rainy one. When buying corms from Holland, be prepared for the fact that they will decorate your flower bed only once, but it will be a wonderful sight;
- do not plant babies and large corms next to each other, because large corms will depress small ones. Plant them one after another moving from small corms to large ones. The largest corms should be planted separately;
- the depth of planting should be appropriate: in light soils it equals to four corm diameters, in heavy soils it equals to three corm diameters. If you do not put it deeply enough, you'll have to stake them when flowering; if you plant it too deeply, gladiolus might not bloom at all.
- three to five days before planting clean the daughter corm from dense scale leaves, otherwise it may not germinate, and after planting water them every other day;
- gladiolus plant thrives in light, so in the shade late varieties will not bloom at all. Only early varieties can be planted in the shade and partial shade, but in this case they will not bloom early as well;
- the site with gladiolus should be ventilated, otherwise fungal diseases may occur;
- if your gladioli grow in sandy loam, apply foliar top dressing, that is spraying the leaves with liquid fertilizers;
- in summer gladioli are watered once a week, but very abundantly. If the heat is prolonged, then in order to avoid the soil overheating you should water them every evening with consequent loosening of the soil, earthing up and weeding;
- harvesting and storing of corms are very serious and important.
3-4 weeks before planting you must carefully clean the corms from dense scale leaves, without damaging the shoots, take away all sick or partially injured corms. You can only leave the corms that are slightly affected by sclerotinia or scab, cutting out the lesion focus and treating the sore spot with a brilliant green. After cleaning off the scales and treating the slices, the gladiolus corms are laid in one layer with a sprout upward and kept in a warm light room for the shoot to emerge. Before planting corms are treated with chemicals to neutralize thrips and fungi, immersing them in a 0.3% solution of potassium permanganate for 1-2 hours or in a 0.3% solution of a fungicide for 1 hour. If the treatment is carried out just before planting, soak the corms in a solution (0.02 oz of manganese crystals per 35 fl oz of water) for half an hour and then, without rinsing, plant them immediately.
Baby corms of gladiolus also need to get prepared for planting. 10-15 days before planting, choose a baby corm 0.2-0.3 inch in a diameter (if the gladiolus variety is not large, you can take a smaller baby corm) with noticeable root knobs and take away a hard shell that covers them. Then place them in boxes in one layer and keep them in a scattered light. Sprouted babies should be immersed in a solution of potassium permanganate (0.04 oz per 35 fl oz of water) for 9 hours for decontamination.
Since this plant has certain biological peculiarities, growing of gladioli requires observation of some rules. Gladioli thrive in light and warmth, so the site for their planting should correspond to these requirements.
So, as to the choice and preparation of the site for the gladiolus planting, it should be light, draft-protected with well drained soil. The colder climates zone is, the lighter the planting site should be, since even a barely noticeable shading delays the growth and flowering of gladiolus. In addition, it is not advisable to plant gladiolus in areas with high standing of groundwater. In the southern regions shade is acceptable at noon time. The site should be horizontal or be located under a small (5 °) slope to the south, so that excess water can drain out.
Soil acidity is also an important key to success in growing of gladiolus. Weakly acid soil with 6.5-6.8 pH is preferable. With a higher acidity, the tips of the leaves of the plant darken and fade, and the flowers do not open well, fusariosis appears. In an alkaline medium, the iron in the soil becomes insoluble and inaccessible to the gladiolus roots, therefore the formation of chlorophyll in the leaves of the plant gets slowed down and they begin to turn yellow. To neutralize the acidic soil, you should add chalk, dolomite flour or eggshell when digging up the soil (5.3-7 oz per 11 ft²).
In addition to black soil, the best soil structure for gladiolus is light loam or sandy loam. To create such a structure you should add sand to heavy loam, clay to sandy soil with humus and rotted compost. If the site is warmed up well, it needs to be dug up directly before the corms are planted. In the arid zone in order to keep moisture in the soil, the main digging up is done in autumn, and before planting the bulbs you should only slightly loosen the soil. The best predecessor plants for gladioli are vegetables, legumes or perennial grasses, and it is not preferable if the predecessors are roots or asters. The width of the row is approximately 3.3-4 ft.
If in autumn you already know where gladiolus will be planted in spring, add dry phosphorus (3.5 oz of superphosphate per 11 ft²) and potassium (1-1.4 oz of potassium chloride per 11 ft²) fertilizer to the soil when digging up the site. Potassium-free potassium fertilizers (potassium sulfate or calimagnesia) should be applied after winter before spring digging up. Autumn digging up should be 4 inches deeper than spring digging up.
The furrow is poured with water or a solution of fungicide, put 1 inch layer of river sand or a layer of moss-sphagnum (it would be even better), place the corms and sprinkle the soil over them. Moss will protect the corms from the rot, retain moisture in the soil even in extreme heat.
You should care for the planted gladioli attentively. When shoots reach a height of 4 inches, try to mulch the garden with a 2 inch layer of humus: it will protect the soil from dehydration and overheating and supply water to the bulbs. You should water gladioli very abundantly once a week early in the morning or late in the evening – 2.2-2.6 gallons of water per 11 ft². It is better to pour water in the furrows between the rows that are 1.2-2 inches deep to prevent drops from falling onto plant leaves, followed by loosening the soil to a depth of 2-2.4 inches for the crust not to form on it, and earthing up the gladioli. It is desirable to loosen the soil at least once every ten days, regardless of the presence or absence of precipitation. In the very heat, water gladioli every 3-4 days, otherwise the flower will become faded, and the last flowers will dry up without opening out. When the buds appear, tie the peduncles to the pegs if it is necessary, and do not forget to remove the spent flowers for the plants not to waste nutrients for unwanted seed ripening.
Care for gladioli also implies weeding that is usually needed 3-4 times during summer. Keep your eyes on the weeds not to choke the shoots, otherwise the blossoming of gladioli may be in danger. In addition, if the site is full of weeds, there is a greater risk of diseases and slug attack.
Gladiolus also needs organic fertilizers that should be applied in liquid form as it allows to deliver fertilizers directly to the root system. At the beginning of the plant growth, you should use the infusion of bird droppings (3 buckets of bird droppings are infused in 4-5 buckets of water for 10-12 days, then 35 fl oz of this infusion is diluted in 2 gallons of water and poured into the inter-row groove, followed by loosening and earthing up). Liquid mineral fertilizing is carried out every 2-3 weeks, but after August 15 it is necessary to stop feeding gladiolus. Do not use horse manure as a fertilizer.
You can achieve good results by applying foliar top dressing, that is spraying of plant leaves with a solution of mineral substances that promotes the flowering of gladioli and increases their ornamentality. For this purpose you should use solutions of boric acid (2.3 gr per 35 fl oz of water), copper sulfate (3 gr per 35 fl oz of water) or 0.15% solution of manganese. The leaves are fed 2-3 times during the summer at the beginning of growth and during the budding period by adding a little soap to the solution and trying to process the both sides of the leaf.
It is very important to cut gladiolus correctly. You need to do this with a sharp knife early in the morning or in the evening so that the rest of the peduncle should be left deeply hidden between the remaining leaves that must be at least four on the plant to ensure the further growth and development of the corm.
Gladioli should be dug out in autumn from the middle of September when it will be 35-45 days after flowering. Ripe corms that are ready for digging out have the root covered with scales, babies corms are also covered with dense scales and get easily separated from the mother corm. Digging out should be carried out in dry weather, at first you should start with earlier varieties ending with late ones. Small corms and baby corms are the last to be dug out. If you notice that the corms are damaged by black or brown spotting, you should dig them out as early as possible to save them from other diseases.
You can mow the stems before digging out, or you can cut them out with a pruner after digging out the corms. Roots should be pruned as well. Then soil should be shaken away gently, the babies should be separated. Corms are placed in boxes with a fine-mesh or net bottom, each variety should be kept separately from the other, and washed under running water. Then they are decontaminated by immersing in a one-percent solution of a fungicide for 20-30 minutes, then they are rewashed with water, treated with a 3% solution of potassium permanganate, get dried for three days, then placed into the boxes covered with paper and stored at 77°-86°F, turning them from time to time. In 10-15 days the temperature is lowered to 64°-72 °F. In 30-40 days corms can be cleaned and sorted.
Upper and the dirtiest scales are removed and the babies are separated. Gladiolus baby corms – what to do with them? First, they are sorted according to varieties and sizes. A baby corm is considered to be large if it is 0.3 inch in diameter and larger, an average baby corm is about 0.2 inch in diametre. Then the babies are placed in paper bags that are stored at a temperature of no higher than 41°-43°F. To store corms at a higher temperature is dangerous as it can lead to loss of germination. In the city apartment you can store the babies in the refrigerator.
If in winter you have to keep gladiolus in the apartment and if you have a "no frost" refrigerator, use the lower shelf of the refrigerator for storage: simply put the corms into sealed containers so that they do not dehydrate during storage. But be sure to wrap them with paper. Closer to spring, the corms begin to “breathe”, producing moisture, then it will be necessary to get them out of the refrigerator, unfold, dry, wrap in another paper and put again in the refrigerator, but in a cooler place. In relatively warm climate zones, for winter gladiolus can be placed in an insulated balcony or loggia, putting corms into boxes and placing them on a wooden pedestal. When it is cold, you can wrap up the boxes with a blanket or an old coat.
If you still have to store corms in the room, try to place them out in one layer so that they do not touch each other. The corms, of course, will diminish greatly during winter, they will dry up, but if you soak them in a growth stimulator before planting and then take good care of the gladiolus on the flower bed, it is likely that their blossom will be no worse than of the other gladioli.