I tried to set up a crop, just like the wheat, however when the block gets updated it breaks (when placed on farmland it breaks and turns the farmland to dirt).

Actual Crop Class: 

public class CustomCropBlock extends CropsBlock implements IGrowable
{

	public static final IntegerProperty CROP_AGE = BlockStateProperties.AGE_0_7;
	
	public CustomCropBlock(Properties builder)
	{
		super(builder);
		this.setDefaultState(this.stateContainer.getBaseState().with(this.getAgeProperty(), Integer.valueOf(0)));
	}
	
	@OnlyIn(Dist.CLIENT)
    protected IItemProvider getSeedsItem()
    {
       return ItemList.spinach_seeds;
    }

    @OnlyIn(Dist.CLIENT)
    public ItemStack getItem(IBlockReader worldIn, BlockPos pos, BlockState state)
    {
       return new ItemStack(this.getSeedsItem());
    }
    
    @Override
    protected boolean isValidGround(BlockState state, IBlockReader worldIn, BlockPos pos)
    {
        return state.getBlock() instanceof FarmlandBlock;
    }
    
    @Override
    public IntegerProperty getAgeProperty()
    {
        return CROP_AGE;
    }
    
    @Override
    public int getMaxAge()
    {
    	return 7;
    }
    
    @Override
    public boolean canGrow(IBlockReader worldIn, BlockPos pos, BlockState state, boolean isClient)
    {
    	return !this.isMaxAge(state);
    }

    @Override
    public boolean canUseBonemeal(World worldIn, Random rand, BlockPos pos, BlockState state)
    {
    	return true;
    }

    @Override
    public void grow(World worldIn, Random rand, BlockPos pos, BlockState state)
    {
    	this.grow(worldIn, pos, state);
    }

    @Override
    protected void fillStateContainer(Builder<Block, BlockState> builder)
    {
    	builder.add(CROP_AGE);
    }

}

 

Then the block gets registered in a method 

BlockList.spinach_crop = new CustomCropBlock(Properties.create(Material.LEAVES).doesNotBlockMovement().sound(SoundType.CROP).tickRandomly()).setRegistryName(location("spinach_crop"))

 

8 hours ago, modders2 said:

Material.LEAVES

Give it Material.PLANTS instead of LEAVES. LEAVES is a solid Material and therefore turns farmland back to dirt.