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
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