Choosing the best time to apply hydroseed or hydromulch is crucial to a revegetation project as the weather can play an important part in the success of achieving germination of vegetation.
The amount of expected rainfall is a vast factor that can determine how fast germination and establishment occurs, as well as how much of the seeded area establishes. It is important for project costs too, for example, if there is inadequate rainfall forecast (possibly due to dry seasons), irrigation may need to be supplied, adding to water consumption and labour costs. Average temperature can also play a part in successful revegetation, particularly with hydroseeding. If the temperate is too cold, and no mulch has been used for insulation, the rate of germination for seeds can be slowed or inhibited. If the temperature is too high, more water is needed to keep the seedling healthy after germination.
Using a hydromulching technique can substantially reduce these issues, due to its ability to balance out fluctuations in moisture and temperature, but not eliminate them entirely. The type and amount of binder and mulch used can be customised for the specific application and project. Timing your spray seeding application to avoid any high rainfall events is also recommended to reduce the possibility of washing away seed, mulch and topsoil before seedlings germinate.
In the temperate to subtropical parts of Australia, winter through to late spring is usually the best time to conduct spray seeding. There is enough water from rainfall to keep the ground or mulch moist enough for germination and to keep young plants healthy. The temperature is low enough to allow the plants to become well established before the harsh summer sun hits. If a hydroseeding solution is going to be used, application should be timed so that no heavy rainfall events occur in the short time immediately after application to avoid any potential wash away. Hydroseeding will not provide any erosion control until germination establishes.
In the northern subtropical to tropical parts of Australia, where there are distinct wet and dry seasons, spray seeding application should preferably be done just before the wet season starts. This will provide enough water for germination to occur and to stabilise the soil before widespread, heavy rainfall occurs. If application must be done while heavy rainfall is likely to occur, mixtures with higher rates of mulch and binder can be utilised. Wet season products such as a Bonded Fibre Matrix or even FlexterraTM can be used as they are able to withstand much higher shear forces before failure, providing enough time for vegetation to establish.