starting winter growing bulbs/seed

[Uli]

Dear All,
After the BX distribution has arrived, I received questions of members how to start seed or bulbs of winter growing bulbs, in particular Gladiolus species.
Here are copies of my replies for all of you.

What the dormant corms/bulbs do not like is the combination of hot weather and moist soil. Some do not mind but many may rot. The same applies if the winter growing plants get too wet and too cold at the same time. Again, some do not mind, some might even take a few degrees of frost (I have not tested that and do not have frost in my garden) but it is better to avoid this combination in winter.

What must be avoided by all means is drying out of plants in full growth. If that happens (it has happened to me....) the plants will not die, they are geophytes after all. But if a certain degree of drought occurs, it will trigger the beginning of a premature emergency dormancy regardless in which state of growth the plant is. This is an emergency mechanism which secures the survival of plants in nature as many come from very dry habitats with unreliable rains. Once dormancy is initiated this process cannot be reversed by watering. The resulting bulbs will be much smaller than normal and flowers or flower buds will be aborted.

There is one aspect to pay attention to: if you receive very small bulbili/cormlets (smaller than a rice grain) they may benefit from the following treatment to break their dormancy. These very small bulbili are a life insurance of many bulbs and corms and can have a prolonged dormancy which means they may not sprout after planting. This can be overcome by soaking the bulbili in a cup of water at room temperature and adding just one drop of liquid dish washing detergent. This wakes them up, soaking over night is enough, max 24h. After this treatment they must not dry again and need immediate planting, water once and then treat like adult corms.

Talking about frost: I have visited South Africa twice, once in their spring and once in their summer, the seasons are inverted in the Southern Hemisphere. I was surprised how cold the nights could get in spring and although I did not experience this myself I was told that in mid winter there is frequent morning frost in some areas. I am talking about the areas most winter growing bulbs come from and not the skiing resorts on Drakensberg where I have never been.  So depending on where the plants come from, they are used to be exposed to frost. BUT.... frost in a climate like South Africa, California, Chile or the Mediterranean is not comparable to frost in central or northern Europe. What is called an early morning frost in subtropical climates never penetrates into the soil and in general the frost only lasts a very few hours before and during sunrise.  Daytime temperatures are then well above freezing or even warm. This constellation happens on clear, bright and dry days, so the plants exposed to frost are generally dry and not wet. I am writing this to avoid misunderstandings about frost tolerance of some plants. My recommendation is go grow winter growers frost free.

Growing South African Gladioli in northern European winters needs the following conditions: a place as bright as ever possible, full winter sun is best. Protection from rain (and snow) and frost but not warm either. The corms can be started into growth now, obviously in pots. These pots can be placed outdoors in a bright position. Dormant corms should be watered once after planting and then observed for shoots. Only water again after the first shoots have appeared. Pots should not be too small. In very wet conditions protection from too much rain is needed until growth is in full swing. Growing Gladiolus need regular water and must not dry and can be exposed to rain. Once the temperatures drop and the weather deteriorates, the pots should be removed from the garden and best brought into a cold greenhouse which is kept just frost free. Now it is important to find the right balance between temperature and water.  The pots must never dry out, okay. But during overcast grey winter weather they must not be soaking wet either. If you use saucers never allow the pots to stand in water except for those species which require that (Zantedeschia, Onixotis for example) Air humidity is also important. A greenhouse must be ventilated in order to avoid mould forming and condensation on the plants.
If there is no greenhouse, a compromise might be a very bright windowsill in a cold room. Never place winter growing bulbs in a heated warm room with dry air. Indoor cultivation remains a compromise, light intensity is most likely too low and at the same time temperatures too high which leads to etiolated plants prone to aphids. If there are not too many pots it might be worth the effort to move them outdoors during mild sunny weather and bring them in again in bad weather.
Fertilizing will be discussed in a separate mail.
Happy growing!
Uli

[Uli]

Dear All,

There is a thread on South African gladiolus on the email list to which I replied. I agree what was written but
as the membership is living in many different countries and climates and some may be beginners, I would still like to go into some details nevertheless.
In general, it does not hurt gladiolus seed if the winter growers are sown too early. They will germinate once the conditions are right, however, a seed pot should not be allowed to dry out completely after sowing. Even if germination may be delayed. The trigger for germination is the combination of cool weather and moisture (rain) and also a marked difference between night and day temperature. So the best timing is when this is going to happen in your climate. It will be much later the warmer your local weather is.
On the other hand, sowing too late may kill the seedlings during their first dormancy. Simply because they did not have the time to form a corm (or a bulb in other genera) which is big enough to survive the first dormancy. As a rule of thumb I stop sowing winter growers around Christmas for the very latest in the northern hemisphere.
Summer growing gladiolus should be sown in spring. They are less prone to loss during their first dormancy because a cool and dry winter dormancy is less demanding on the seedling corms than a hot and dry summer dormancy.
If you miss the best time to sow, it is no problem at all to wait for the next season, gladiolus seed can be stored (best in a fridge, not the freezer) for quite some time.

Once germination gets going, the small seedlings do benefit from repeated low dose fertilizer. And it is important to keep them green as long as possible in spring when the weather warms up. The longer they remain green the bigger the young corms will be. Rising temperatures trigger dormancy. So depending on where you live it might be a good idea to move the seedlings out of a greenhouse to a shady place in the garden  or to move them from a place with full winter sun to a shady and cool place as well. That is what I do, my bulb seed is sown outdoors in a sunny place exposed to all weather in southern Portugal. During periods of heavy rain I protect from too much rain but without impairing ventilation.
In general I do not repot my gladiolus seedlings but leave them in the same seed pot for another season. I am always afraid that I might lose some of the often tiny one year old corms in the process.

Hope that helps, happy sowing!

Uli

[Uli]

Here is my reply to another question I received

Fertilizing: I use a mineral fertilizer in powder form which must be dissolved and diluted in water. The NPK formula is 8-12-24 (+4) Are you familiar with the NPK formula? N stands for nitrogen which induces lush leaf growth, P for phosphorus, needed for flowers and K for potassium. Potassium will produce strong tough tissue and large bulbs. The (+4) stands for 4% of extra trace elements. This is an expensive fertilizer but as it comes as a powder a packet will last for a long time. The high potassium content and the low nitrogen make this fertilizer ideal for bulbs, succulents and cacti and even orchids but for orchids I only use less than half of the recommended strength. I fertilize all my potted bulbs by hand with a small watering can with the diluted fertilizer. Concentration as recommended by the manufacturer. As this is quite time consuming I generally only do it three time during the growth cycle: once the bulbs start into growth, second round before flowering and then again after flowering but before dormancy. This applies to adult bulbs. With seedlings I use a slightly weaker solution (maybe 30% more water or so, cannot say it more precisely)  and more often. I always leave some of the diluted fertilizer in a sealed container to have it at hand if I feel a plant is hungry. I have never ever lost seedlings or bulbs with this regime. For seedlings especially I do an overhead watering with a fine rose with clear water after fertilizing to wash off remains of the fertilizer from the leaves. Especially hairy leaves might get damaged if droplets of the fertilizer remain and dry on the leaves. I also have other fertilizers for other plants, for example a nitrogen rich one for lush foliage plants like Philodendron, Alocasia/Colocasia, palms and the like. It would not be a good idea to use the two fertilizers the opposite way.

Uli

[CG100]

It probably only works in English, but -

NPK - shoots, roots, fruits (fruits can only be formed after flowering).

I like to start growth with just water, then a high nitrogen once started for just one or two waterings, then high potash for a couple of waterings during growth, then a low nitrogen as they go dormant - Chempak 2, 4 and 8.

Exceptions (not bulbs) - Proteacae, whch dislike nitrate, so really need urea as a source of nitrogen, and citrus, which do far, far better using commercial specialist citrus fertilsers.

[janemcgary]

I don't grow South African gladioli, except one that is a pest in my garden, but here are comments on somewhat hardy geophytes and starting winter growth. I usually water the bulb house when daytime temperatures drop below 80 degrees F and the first measurable fall rain arrives. That happened a week or so ago here in western Oregon. I will keep the soil from drying out until May. My plants experience frost even under the solid roof of the bulb house, since the sides are open (protected by wire mesh), down to around 20 F/-6 C. Some plants are growing directly in raised beds and others are in plunged pots, mainly clay pots. I can't grow the really tender South African genera such as Lapeirousia, but in the collection are many Mediterranean and Californian, and a few South American, species referred to as tender in standard gardening books.