Hibiscus Rosa Sinensis Propagation
by Hybridizing, Seed Collection, and Planting.

Let’s talk about seeds and seed pods. I know most of you might know this information, but we still get people every day asking for seeds thinking they can replicate the bloom like most other plants. Here are some key points you need to know.

1. Hibiscus seeds do not regularly naturally occur on exotic hibiscus (Hibiscus Rosa Sinensis). It can happen but not normally. They usually need to be pollenated by humans.

2. Hybridization is the process of applying ripe pollen of one variety to the stigma pads of another flower early while the pads are still sticky. This starts a 40–70 day process before the seed can be collected.  Each seed in a pod will produce a genetically different plant that will be a new variety. Just like with humans the female gives some genes and the father the rest. There are so many variations that the bloom rarely looks like it’s pod mates but will usually have some similarities, just like your brothers or sisters.

3. The planting of the seed and the year or two wait after germination for that first flower requires considerable dedication, particularly when about one in 50 to 100 will be significantly different from existing cultivars and of acceptable form and texture for distribution to other growers. The rest should be culled.

4. Because there is work involved in producing the seeds and therecan be a high failure rate they usually cost money. Expect to pay $2-$5 per seed.

 If you’re getting a great deal like 10 for $2, I’m willing to bet your getting mallow, (Hardy Hibiscus) seeds which are virtually worthless or even something that is not hibiscus at all.

5. If someone is selling seeds and they show a bloom and say that you are getting seeds that produce it THEY ARE LYING AND RIPPING YOU OFF! If they show a true blue, green or black bloom they are probably deceiving you.  Please contact me and I’ll try my best to answer. Find out before you order anything.

 6. Tropical hibiscus seeds are not the easiest to grow. There is a learning curve and you may have to adapt it to your setup. Don’t get frustrated. I can’t tell you how many I killed before I started getting success.

Pollination

In Australia the best time to hybridize is the period from April to August. The cooler weather is ideal. High temperatures dry out or inhibit the pollen so that it is not viable. Pollen may be stored in vials in the refrigerator until a wanted female parent blooms.

Even before the blossom opens, the stigma pads are receptive to pollen. When the bloom first opens, the anthers bear light-coloured kidney-shaped sacs. As the morning progresses, these sacs open, dehisce is the technical term, and bright yellow pollen is exposed. This pollen is now ready to apply to the stigma pads of the selected pod parent or female. This may be done with a soft brush, or the bloom of the pollen parent may be picked and the pollen applied directly to the stigma pads, taking care to cover each pad thoroughly. Day-old pollen may be used if it has been kept in isolation, but the pod parent must be fresh, so that the stigma pads are sticky, and the pollen will adhere to them. Each grain of pollen then grows a tube down through the style and hopefully fertilizes an ovule in the ovary.

Recording

At this point the cross should be entered in a stud book, giving the cross number, date, name of pod parent (female) and name of the pollen parent (male), leaving space to enter the date of harvest and number of seeds. This will all go on one line in the book. A light tag should be attached to the stem of the pollinated flower, giving the cross number, the date, and names of both parents, mother first and father second.

When crossing two singles there is a much greater chance of getting singles than doubles, although doubles will occasionally result. When crossing a single and a double the chances of getting singles and doubles are roughly equal. Most double hibiscus, but not all, because of the arrangement of their floral parts, are useless as female parents although they can be used as pollen parents.

Maintenance and Harvesting the Seed

After the petals fall the fertilized ovary enlarges. In a few days the calyx tips should be trimmed away carefully to prevent the harbouring of insects. It is important to keep insects off the pod in the early stages, for sometimes insects will sting a seed capsule and one of the sections will die. More seeds are lost from insects than from any other cause. It is a good idea to carry with you in the garden a small squirt can of a mild solution of insecticide to spray the pods, or an insecticide dust.

The pod will ripen in 40 to 90 days, some earlier, turning from apple green to light brown. At the earliest sign of cracking open, a square of nylon net may be tied around the pod to prevent loss of seed. I use the Organza jewellery bags. When the pod cracks open it should be picked, the seeds counted, placed in a shallow container to dry, then transferred to an envelope or box and marked with cross number, date, and other information. In general, the larger the seed, the larger the flowers will be.

Planting the Seed

Some hybridizers plant the seeds immediately, others let them dry for several days to several months. Seeds, once dried, can be successfully stored in a container in the vegetable crisper of your refrigerator.

Before planting, a suitable seed germination medium must be obtained. A good seed raising mix can be Root It sponges, compressed Jiffy pellets, a mixture of vermiculite or perlite, and peat or a mixture of sand and peat, or a commercially available medium such as Rocky Point Seed Raising mix.

In profile, the seed appears much like a human head. Hold the seed by the face to protect the embryo and then with a single-edged razor blade nick or scalp the rounded top of the head until a white dot appears to hasten germination. If you have difficulty finding the top of the head, take the seed between your thumb and finger and roll it a couple of times and it will stop in the right position. Because it is tapered on the bottom it will stop with the narrow part down and you can nick the top of the head.  

You should soak the nicked seeds overnight, each lot in its own labelled container. Caps from wine or spirits bottles are perfect. Use cool boiled water with 10% of hydrogen peroxide. (Available from the chemist. I use the 3% solution) While the seeds are soaking overnight prepare your planting medium and pre wet.  

Drop the seed, nicked part on top into a depression of about 6-10mm deep and cover.  I use a seed tray with its own dome, available at Bunnings. It is best to keep the temperature at about 28°C and the medium moist, but not soggy. In colder climates a heat mat to provide bottom heat is helpful. It is essential that you do not use too much water. Seeds will rot and will not germinate if they stay in a wet/soggy medium.

 Growing the New Seedlings

 When properly nicked and planted, seeds should germinate in 6 to 30 days.

After the first four true leaves appear, the seedling should be potted, and if the peat blocks were used they must be covered with the potting soil. Use a sterile quality potting mix. Be sure to keep baby seedlings on the dry side if they are in a heavy medium. Pots for young seedlings should be sterile. When they are quite small, seedlings can be planted directly to beds rather than pots in cooler weather.

Hibiscus seedlings in full sun tend toward development of stocky, branched plants, with possibility of earlier bloom. Dense shade will definitely retard the first bloom.

Most seedings will bloom in 10 to 14 months. Some take much longer. Do not cut back, as this will delay blooming. Retain only the best, those with promise. Discard those which are undesirable. To help minimize the proliferation of undesirable seedlings, it is worthwhile to observe the plants for a year or two after they have begun to bloom before releasing them or registering them.

In your breeding programme, I would suggest using only prolific bloomers, with fully overlapped petals, with a heavy to medium textured flower. This should ensure that at least you will have quality. To be a worthwhile seedling it must have acceptable qualities that are better than any other variety in its colour range. Out of 20 seeds from a pod, each plant raised will be a different colour or colour tones.

Recycling Your Excess Seeds

The Seed Bank. A seed bank is a vital part of the Australian Hibiscus Society's programme. Members of the society who are hybridizing and have more seeds than they care to plant are asked to send them to the Secretary of the Australian Hibiscus Society. Include the following information: Parent identity - mother first then father - then date of cross. Place the seeds in an envelope, write the above information on the envelope, and protect with corrugated cardboard or place in a small box for mailing.  Mark "Fragile" and "Please handle carefully".
 

View this seed nicking video