Despite our best efforts, we may end up with deaths of trees in the first year or poor germination and survival from direct seeding. In this case it is sometimes necessary to carry out additional plantings to fill gaps or to replace species that have failed or are underrepresented.
Before you plant you should set yourself a level of survival below which you will replant or fill in gaps. This is often a personal judgement, but many planters will replant if they get less than 50-75% survival. You should monitor within one month of planting when deciding on replacing failed plants. This allows you to take advantage of your existing weed control and ground preparation and to conduct your replants in the most suitable season. Replanting beyond 3 months after planting is rarely successful. You should however, monitor survival at 10 months after planting. If survival is poor at this stage you will need to prepare your site again for replanting. You can spot spray with herbicide to remove weeds and then replant again in the ideal season. In some cases you may need to prepare the ground again if it has compacted or is difficult to plant into. You can use a rotary hoe to get between existing trees or use a tractor-mounted auger to prepare individual planting holes. If survival is very poor it may be worth cutting your losses and preparing the site properly before replanting.
Direct seeding depends on favourable climatic conditions for successful germination and often these conditions do not occur in the first year after sowing. Many Australian species are able to stay viable in the soil for several years, and will germinate two or three years after sowing. Therefore it is best to be patient with direct seeding. If germination is still poor after 3 years, or if you get a high germination but low survival, you should consider starting again. If you get an even scatter of trees across a site, you might consider using tubestock to fill in gaps or add missing species.
As the successful trees get bigger, it is more difficult to successfully establish other plants among them as their roots become very competitive and they begin to shade out new plants. If you intend to revegetate your site in stages it is best to leave whole rows unplanted, rather than try to plant between existing trees.