GROWING REQUIREMENTS FOR YOUR PELARGONIUMS

By Marilyn Holt of Holt Geraniums

ZONALS

Zonal pelargoniums require the same temperatures that we feel comfortable with, 55°F - 60°F at night and 70°F - 75°F during the day. Also like people, they can make do with a variance of temperatures, but must not be subjected to below freezing temperatures. Pelargoniums seem to cease most growth when the temperature is over 90°F and they use less water than at more moderate temperatures so check to see if the soil is really dry, below the soil surface, before watering.

Zonals like the same lower humidity we do, not the humid hothouse conditions of ferns or orchids. They should not be put in saucers of water as the root area will soon rot. If a saucer is used, it should be emptied a few minutes after watering. If given proper care and sufficient light, zonals will bloom most of the year.

UNUSUAL FLOWERED ZONALS

The cultural requirements for unusual flowered zonals would be the same as for regular green leaf zonal pelargoniums.

FANCY, SILVER, GOLD AND TRI-COLOUR ZONALS

The cultural requirements for the these would be the same as for regular green leaf zonal pelargoniums. The main concern is protection from sun during the hottest part of the day in areas of the country that reach the middle to high 90's F. A good rule of thumb is, the less green on the leaf, the less intense noon-day sun they can tolerate. These plants do not always seem to have as strong a root system as the green leaf varieties so careful attention must be paid to water and feeding. With the smaller root structure it is important not to overpot the fancy leafs as too little root and too big a pot usually leads to root rot.

DWARFS & MINIATURE ZONALS

Though basically these plants are zonals, because of their small size and smaller pots, attention must be paid to their welfare. They are excellent windowsill plants but it must be remembered that in winter it should be a south facing window as none of the zonals are tropical. They must have sufficient light and can be easily grown under lights. If kept on a windowsill indoors all year, they should be shielded from the intense rays of the summer sun through the glass; a sheer curtain during the afternoon hours would give good protection. In winter a heavy drape or protection of some kind should be between the plant and the cold glass if outdoor temperatures are below freezing. If given proper care and sufficient light, they will bloom most of the year.

STELLARS & FORMOSUM

These plants require basically the same care as zonals. Their main concern is afternoon shading in areas that receive high heat (90F+) in the summer. They do not tolerate long periods of intense sun very well. Stellars require relatively low light to bloom so if brought indoors during the winter you will find they bloom quite readily.

IVY LEAF PELARGONIUMS

Ivy pelargoniums require a little closer attention to watering than their zonal cousins because of their waxy leaves. An ivy, if overwatered, is unable to transpire moisture through its leaves and will develop a condition called ‘edema’ where the underside of the leaves will form brown, corky-looking spots and craters. This is the result of leaf cells becoming engorged with water and, in a sense, having a minor explosion. It is not harmful to the plant but it is unsightly. It is sometimes impossible to avoid this condition during times of rain or high humidity, but it can be alleviated by using very fast-draining potting soil. The plant should not be allowed to dry out but should be checked carefully before watering. In coastal areas they flourish in full sun, they will perform much better with afternoon shade in inland areas of high heat and intense afternoon sun.

SCENTED LEAF

Scented leaf pelargoniums can be grown in pots or planted straight into the ground. If planted in the ground you must bring them indoors for the winter, or take cuttings to bring indoors. The second method would probably be better because if planted straight into the ground they usually attain quite a size, depending on the variety.

Scented pelargoniums grow best in slightly acid soil. Watering of scented leaves varies with the season and the variety of plant. Mature specimens, especially those that are root bound, need to be watered much more frequently than do young plants in new soil.

REGALS

Basically the same requirements as for zonals, the main difference is in the heat tolerance of regals. In most parts of Canada they do extremely well and will have magnificent blooms throughout the year, but in areas where the temperatures even at night are above 70F summer blooming will cease. All blooming can be extended if the plants are put in an area of morning sun and afternoon shade, or placed under the dappled shade of a tree or lath shelter. As the regals are larger, woodier plants, they require larger pots. Also, because of their size, they require more water than zonals.

ANGELS

The culture of ‘Angels’ is somewhat similar to the culture of ‘Zonals’. They greatly dislike wet feet and the potting mix should be one that is fast draining. They will require the usual feeding especially during the heavy spring blooming period. If they are kept in small pots, very close attention must be paid to water and feeding as this is not a natural size for the plant. They perform at their best in a large tub, urn or hanging basket. They make a spectacular display if put in long baskets to trail over a porch or deck. Another idea is to hang the baskets under trees where they will receive some shade during the hottest part of the day when the sun is overhead.

UNIQUES

These plants will stand the sun better than other pelargonium varieties. They are excellent plants to border a vegetable garden or for the perennial bed, bringing colour throughout the season. They will bloom year round and attain quite a size. Again, because of their size they require more water than regular zonal pelargoniums.

SPECIES & SPECIES HYBRIDS

The true species (those with names beginning with ‘P.’ or ‘Pelargonium’, i.e. P.fulgidum, P.gibbosum, etc.) are from South Africa and can tolerate intense heat. Those that are species hybrids, i.e. ‘Splendide’ [‘Violarium’], ‘Cape Beauty’, etc. are crosses and their cultural requirements may differ slightly, depending on the variety. A lot of the species are winter growing varieties and will go dormant during the hot summer months.

Remember that water is not readily available to these plants in their natural habitat so do not soak the soil. All pelargoniums, whether species or not, DO NOT LIKE WET FEET. Allow the soil to be slightly on the dryer side than the wetter side.

I find that if I plant my species and species hybrids in pots that breathe, they do better. You can use clay pots but remember that the clay will absorb water from the plant roots so you must pay close attention to the plant. I prefer to plant my species and species hybrids in slatted wood hanging baskets or containers. This allows the water to drain quickly and also allows air to reach the root area. I was unsuccessful in growing most of these plants for many years until I put them in these wood slat containers (with the wood slats tightly together), now they bloom quite prolifically and grow quite vigorously.

FERTILIZING

I feed all my plants every time I water with a weak solution of 20-20-20 at the rate of 1 tablespoonful to a gallon of water. I find that feeding a weak solution every time gives the plant a constant supply of nutrients and they attain a consistent growth pattern. Some people water once monthly - if you remember that date you'll be fine, but if you forget the date and water too soon your leaves will be the size of cabbage leaves on the fastest growing section of the plant (usually the top leaves) then the rest of the leaves will remain the proper size until you fertilize again and the pattern repeats itself - you will end up with huge leaves and regular sized leaves rotating up the stem thus spoiling the look of the plant.

WINTER CARE & CUTTINGS

Before threat of frost, bring your plant indoors. If they were planted directly in the soil, dig them up carefully, trim the roots to about 3" all around and group like varieties together in a pot (three to a 10" pot). If potting up separate varieties together, make sure you keep the name tags with each plant. Trim stems to four leaves above the root system, water slightly to set soil around the root balls. Place pots in a cool area out of sunlight. Water sparingly throughout the winter - DO NOT ALLOW THE SOIL BALLS TO DRY OUT COMPLETELY & DO NOT FERTILIZE. Keep plants cooler but make sure there is air circulation around the plants or they may rot. In early spring, repot in individual pots, increase water and bring plants into light to encourage growth.

Another option for winter is to take cuttings of the plants you want to save. If you lack space, this is the best way - it also increases your number of plants. Take 2" long cuttings at the end of August. Cut the stem about 1/8" below a leaf node, remove the bottom leaves and insert in soil (I use Sunshine Mix #1). I don't use rooting hormones but others do, the choice is yours. Place somewhere where they will get bottom heat (on top of a refrigerator, etc.) and keep out of direct sunlight. Rooting takes place in about 2 weeks. I do my cuttings in individual 2-1/4" pots and by February they are moved into 4" pots, by May they can be planted in their new location outdoors. I find by using individual pots for rooting that if one plant rots you don't infect the other plants whereas in a community container they will all eventually rot. In our throw-away society, there are lots of plastic containers you can recycle and use for rooting your plants - the smaller varieties can be rooted in plastic film canisters as long as you use a skewer to pierce a few holes in the bottom to allow water to drain out. If you use the clear ones you will be able to see the root system developing. Most places that develop pictures will gladly give you all the canisters you like (they are also great for collecting and saving seed). The larger varieties will need larger containers but not too much larger than 2-1/2 inches as the soil will remain too wet and the cuttings will rot.

* * * * *