Jorielle's Blog

Geranium
Mar 31, 2008 | 9:39 PM PST
Taking cuttings of geraniums is quite simple.

• First, prepare the soil and pots. You can use pots, a tray, peat pellets, whatever you like. I recommend sterilized potting soil in peat pots or 4 inch cheap plastic pots. If you are using indoor potting soil it's a good idea to add some sand or pumice for good drainage.
• Next, locate some nice cuttings on your plants. Early spring is the best time to do it. Select succulent stems with green growth tips.
• Make cuttings about 4 inches long. Cut straight across with a sharp knife. If you cut on an angle, only part of the stem will root. A straight-across cut is necessary.
• Don't put the plant down on a table and cut down like an axe.
• Do hold the plant out and swipe in the jaunty fashion that florists use in cutting the stem ends off of roses. The movement should be smooth and swift but not dangerous with knives and blades flashing about.
• Strip the leaves (if there are any) off the bottom 1 1/2 inches of the cutting.
• Immediately stick the cuttings into soil. Some people even do the cutting underwater.
• With a pencil, chopstick or similar object poke a hole in the soil where each cutting will go. The hole should be about 2 inches deep. Each 4 inch pot should have one hole. If you are using a tray, the holes should be about 4 inches apart. Rockwool blocks also work well. These are available in the propagation sections of garden stores and also at hydroponics stores. A 2-inch block for each cutting is a good size to select.
• Dip each cutting in #1 rooting powder, available at all garden stores, some hardware stores, and a few florists.
• Stick the cutting in the hole.
• Using the pencil again, poke the hole closed so that the soil is firm around the base of the cutting.
• Water
• Place in a bright location, such as right next to a window. Don't worry about cold drafts; it will build up the garden-readiness of your plants.
• In a few weeks your cuttings will be rooting -- but don't pull them out. That would wreck all that hard work.
• You will tell when your cuttings have "taken" because they will start to grow. Feed them with all-purpose plant food. Schultz green drops (7 per litre) will do. I like Dutch Plant Pills. Just about anything will do to keep them happy indoors until it's time for your geraniums to go back outdoors.

It's far easier to winter over cutting-grown plants when they are started earlier. The ideal time to take geranium cuttings is the first half of August. This gives the newly rooted plants a chance to establish in optimum late summer conditions before they're asked to survive over the winter indoors. A warm south-facing window is ideal for geranium plants. They thrive in warmth and full sun, and don't mind a dryish soil.

It's my preference to winter over young cutting-grown plants because they are a conveniently modest size for wintering indoors at a sunny window. In the spring they can in turn serve as mother plants, sources for more cuttings and an extended collection of geranium plants in the summer garden.

However, if you have the space for them in the house the original mother plants can be cut back and potted in late summer, and kept in a bright location indoors during the winter. In really good conditions, such as in a sun room, they will bloom sporadically through the winter.

Zonal, or common garden geraniums (Pelargonium hortorum) are among the easiest of all plants to propagate from cuttings. The trick is to keep water away from the cutting bases in the pot, because dampness at that vulnerable point causes a rotting known as black leg. And unlike almost all other cuttings, zonal geranium cuttings should not be given a humidity tent during the rooting period -- again, to avoid the damp conditions that are hazardous to these geraniums.

First, prepare containers to receive the cuttings. Bulb or azalea pots are well suited for geranium cuttings, because their shallow depth helps prevent the problem of an overabundance of damp soil below the cuttings.

Scrub the containers with hot, soapy water, and fill them with a sterile, lightweight, porous planting mixture. The main thing is that the blend stays open in texture and does not compact or hold on to excess moisture. Tiny, fragile roots must be able to penetrate it easily and not be subject to rot by waterlogged conditions.

I usually start with a ready-made mix such as Redi-Earth and add half as much sterile, bagged soil. To increase aeration in the mix I add perlite, about half as much as the soil.

Select only your best plants from which to take cuttings. Look for healthy, vigorous plants that have produced the most numerous, beautifully formed and vibrantly colored flowers. If you have several different varieties, or colors of geraniums that you want to duplicate with cuttings, take the cuttings from each one separately. Have a container filled and ready for each set of cuttings and label each one right away.

To make the cuttings, either snap or cut off growth four to five inches (10 to 12.5 cm) long. Remove any flowerstems from the cuttings and shorten them to about three inches (7.5 cm), making a slanting cut immediately below a leaf joint. Remove the lower leaves and little leafy wing-like bits that grow along the stem so that none of these will end up beneath the soil.

Poke a hole into the planting mix with a pencil and insert the cutting, firming it securely into the mix. Place the cutting deeply enough so that it is well supported. If you are rooting just one cutting, use a pot three inches wide. If you are rooting several, use a communal pot eight to 10 inches (20 to 25 cm) wide.

Group cuttings are best placed around the outside edge of the pot, with a small indentation left in the middle for watering. Adding only moderate amounts of water to the centre of the pot keeps each cutting watered while allowing it to remain a bit on the dry side at its vulnerable point. When watering a single cutting, direct the flow of water away from the stem around the pot rim.

For the rooting period set the cuttings in a warm, bright place out of direct sun. Coolish air temperatures (to minimize evaporation from the leaves) together with warm soil to induce fast rooting are ideal. Pot the cuttings in individual containers as they root and begin to show new growth.

Outdoor Geranium Culture

Wait to plant geraniums outdoors until frost danger has passed and the soil temperature reaches 60°F. Choose a site with lots of sunlight, ideally eight hours or better. With less sun, the plants will bloom sparsely. Soil should be open and porous to allow for good water drainage, oxygen penetration, and healthy root growth. A heavy soil will benefit from the incorporation of several inches of peat, compost, or perlite before planting geraniums. Do not use manure or vermiculite. Sandy soil will also be measurably improved by the addition of organic matter.

Geraniums will not bloom well if they are overfertilized. Two pounds of 10-10-10 dry fertilizer or 4 pounds of 5-10-5 dry fertilizer for 100 square feet can be incorporated into the soil at planting. A half-rate application of this dry fertilizer can be spread at mid-season in July. Water these dry fertilizers into the soil. An alternate fertilizer scheme is to use 2 level teaspoons of water-soluble 20-20-20 fertilizer in 1 gallon of water, applied every three weeks. Use either dry or water-soluble fertilizer methods, but don’t use both or you will overfeed the plants.

When you plant, make an irrigation furrow or dike around the plants to serve as a reservoir for summer watering.

Water geraniums thoroughly, but allow the soil to dry between waterings to avoid root rot. Do not allow the plants to wilt, however. Cycles of wilting, followed by a heavy watering, cause leaf drop and result in poor growth.

Remove faded flowers and dry leaves from the plants. These attract Botrytis fungus which attacks leaves and young buds. Protective fungicide sprays may be necessary during periods of cool, moist weather. Check your garden center for products labeled for use on geraniums. Fortunately, insects are generally not a problem.

If you have a bright location indoors, you can bring your geraniums inside and keep them growing as houseplants until it’s warm enough to put them out the following spring.

The practice of storing geraniums in the basement over the winter works better with cold, damp basements than it does with dry, warmer, modern basements. 

Indoor Geranium Culture

Prospects for success when growing geraniums indoors depend largely on having enough light to promote flowering. Geraniums thrive in full sunlight. In the absence of a bright, sunny window, supplemental fluorescent tube lighting kept 10 to 12 inches from the plants will help growth. Fluorescent lights can be used from 6 p.m. to 10 p.m. to supplement natural light.

Overwatering will cause geraniums to rot. Feel the soil to determine when to water. If it’s dry to the touch, water thoroughly. If it feels moist and cool, don’t water. Geraniums tolerate dry soil conditions better than excess moisture.

Geranium pots can be either clay or plastic, but must have drain holes. Saucers placed under the pots to collect water should be emptied a few minutes after watering. If a large, shallow pan is used to display several plants, gravel can be placed on the bottom. The evaporating water from the gravel surfaces will increase humidity.

In the home, geraniums do not require frequent fertilization. By potting young plants in a good soil mix (1 part soil, 1 sand, 1 peat), additional nutrition will not be required for two or three months. Water-soluble 20-20-20 can be used at the rate of 1 level teaspoon in 1 gallon of water. For plants that are kept indoors year-round, fertilize during growth periods only.

Geraniums thrive in a wide range of temperatures. Ideally, they should be grown at 65°F day and 55°F night temperatures. Often geraniums are grown at temperatures that are too warm. Many houses and apartments have radiators by the windows to compensate for heat loss. Thus, maintaining plants near a light source without overheating may be a problem. Avoid cold, drafty areas as well as hot, dry locations.

Indoor gardeners should prune or pinch their plants. Removing the growing point will produce a plant that is stocky and well-branched. Several vigorous stems may be allowed to form a shrub-like plant. Occasionally, geraniums are trained into the shape of a tree. To do this, allow a single stem to develop and remove all side shoots. Use a stake for support. When the desired height is reached, remove the top growing point. Allow only the upper side buds to form shoots. With time and shearing, these shoots will form the shape of a tree.

The taller types of Geranium benefit from shearing after the first flush of bloom. Cut all stems to about 3". The plants will put on a new flush of leaves and may reflower.

Basically, you renew an overgrown pelargonium ("geranium") by pruning to the lowest good pair of leaves. Once they've come back to a pleasing shape, keep after them so they don't get leggy again. The growing season for these in SoCal is year-round, so you can prune pretty much whenever you like.

When you prune, try rooting some likely cuttings; these are particularly easy plants to root.

Zonals or Pelargonium hortorum have more succulent stems than Regals.  It is sometimes best to cut back gradually.  Prune each stem back to its lowest pair of leaves.  Wait for some new growth, then cut back some more until the plant is compact and well-shaped.  Stellars should be treated as zonals.  Fancy-leaves must be soft pinched to get side growth.  Dwarfs are slow growing--only pinch for shaping purposes.

CORRECT CUTTING: MAKE CUTS JUST ABOVE THE NODE AND SLANTED so that moisture cannot sit on top of the cut.