How to grow Proteas

Ideally, sorted viable seeds should be soaked in 50 deg C plain water for 30 minutes in a vacuum flask to maintain that temperature. This is more of a sanitation than a dormancy break step. A further soak for 12 hours in 1% hydrogen peroxide (H2O2) as well as a drop of a gibberellin, these are an added extra, and not entirely needed. The seeds should be rinsed and dried briefly so that the hairs fluff up as they are easier to handle when sown into seeds trays. At this stage a dusting of a fungicide should be applied by putting the seeds into a plastic bag and shaking. Smoke water works well for a variety of seeds but less so for some of the Proteas and much less for the hard nut-like seeds of the Leucospermum and Mimetes. For an exhaustive analysis of the effects of smoke water access v the relevant pdf in the index.

With difficult-to-sort seeds it would be easiest to try germinate the entire batch and use a larger seed tray, however the seeds will then be mixed with bracts and other chaff, the worst of which should be sorted out as fungus growth can start as the chaff begins to compost which also then attracts insects etc. A vigorous rub between the hands will separate the seeds from the styles, a sieve may be useful to separate the fine matter. A word of caution: if too much chaff and seed are sown together there is a danger of setting the seed deeper than the ideal of one centimetre or less. For this mass procedure I have sown the seeds in their tray and then soaked that tray for 24 hours in a larger tray with or without the primers. It is not necessary to position the seeds up or down as the emerging radical always orientates itself downwards.

Simply sowing unsorted seeds without any primers or smoke water has worked well for me and I do not use primers for the hairy Protea seeds. However the air temperatures should then be optimal and the medium should never dry out.

The germination of Proteaceae is reliant on the day/night air temperature varying by around 10 deg C (see Leucospermum germination), so the best time is late autumn/early winter when the days are shortening. Inevitably there are cloudier or hotter days, but this seems to matter little when the average fluctuation is 10 deg C and is cooler for a longer autumn night. I use a shallow seed tray (6cm deep x 17cm x 24cm) which allows a quicker natural warming and cooling of the medium that is required for germination to start. Watering should be done in the late afternoon after the sun is off them to aid in the drop of the evening temperatures.

The time it takes seed to germinate (till radicle emergence) varies, but the quickest is around 19 days (Protea mundi), others take 30 days (P nana, P. pityphilla, P. scolymacephela) while others can take longer (P. scabra, P. acaulos, and P. restionifolia). Once germination has begun, I sort through the seed trays every five days as often there is an initial germination, then a staggered germination after that. When working with rare seeds I allow for this and keep the seed trays damp with the same temperature variations for at least a month after the first germinations. This staggered germination may be due to the differing maturity of the plants from which seed heads have been taken, or some other factor like weaker seeds, weaker plants, slower rate of water imbibition by some seeds, position of seed trays relative to the sun angle, depth of sowing etc.

As seed sorting is often inaccurate, I feel that germination numbers per mature seed head is a better measure of viability for unsortable proteas.

Note in the following table that the grafted Protea nana seeds germinated at a very much lower rate than the ungrafted ones that were collected from a natural in situ colony, perhaps indicating some sort of incompatibility of grafting and seed viability. This is forming a long-term enquiry that may indicate a lack of the correct pollinator or some sort of graft disunity. It raised the possibility that endangered ex situ plants need hand pollinating. I hand pollinated half the flowers on a grafted Protea nana and the germination rate for the hand pollinated versus the open pollination was equally poor. I shall be using different rootstock species as well as a variety of scion species. A spray of Boron well before bud opening will be tested as this is reputed to help develop the style down which the pollen germinates.

None of these seeds had a stratification period, instead germination was initiated from room temperature storage. No smoke water, H202 or gibberellin was applied. Germination resulted entirely from open autumn temperature fluctuations and keeping the seeds damp in peat moss. As some had a better germination percentage it might be indicating that additives could have been an advantage for some species.